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Data Communication System Cadillac Escalade GMT900

Communication Devices 19 illustrations ~32409 words

Fastener Tightening Specifications

ApplicationSpecification
MetricEnglish
I/P Lower Trim Panel Insulator Screws2 N.m18 lb in
Power Liftgate Actuator Module Bolt9 N.m80 lb in

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Scheme 2: Data Communication Schematics
Scheme 2: Data Communication Schematics

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Scheme 13: Body Control System Schematics
Scheme 13: Body Control System Schematics

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DIAGNOSTIC CODE INDEX

DTCDescription
DTC B1000B1000 00: Electronic Control Unit (ECU) Performance No Additional Information Available B1000 04: Side Object Detection Performance - RAM Failure B1000 08: Electronic Control Unit (ECU) Performance Signal Invalid B1000 12: Electronic Control Unit (ECU) Performance Below Minimum Threshold B1000 31: Electronic Control Unit (ECU) General Checksum Problem B1000 32: Electronic Control Unit (ECU) General Memory Failure B1000 33: Electronic Control Unit (ECU) Performance Special Memory Failure B1000 34: Electronic Control Unit (ECU) Performance RAM Integrity B1000 35: Electronic Control Unit (ECU) Performance ROM Integrity B1000 36: Electronic Control Unit (ECU) Performance EEPROM Integrity B1000 37: Electronic Control Unit (ECU) Performance Watchdog / Safety Failure B1000 38: Electronic Control Unit (ECU) Performance Supervision Software Failure B1000 39: Electronic Control Unit (ECU) Performance Internal Electronic Failure B1000 43: Electronic Control Unit (ECU) Performance EEPROM Error B1000 46: Side Object Detection Performance - Invalid Configuration B1000 56: Electronic Control Unit (ECU) Performance Allowable Number of Transitions / Events Exceeded B1000 57: Electronic Control Unit (ECU) Performance B1000 73: Electronic Control Unit (ECU) Performance Parity Error B1000 0F: Electronic Control Unit (ECU) Performance Erratic B1000 2B: Electronic Control Unit (ECU) Performance Missing Reference B1000 2C: Electronic Control Unit Performance Reserved B1000 3B: Electronic Control Unit (ECU) Performance Internal Self Test Failed B1000 3C: Electronic Control Unit (ECU) Performance Internal Communications Failure B1000 4A: Side Object Detection Performance - PROM Checksum Error B1000 F0: Side Object Detection RF Transmit Chain Failed B1000 F1: Side Object Detection RF Receive Chain Failed B1000 F2: Side Object Detection Frequency Calibration Failure B1000 F3: Side Object Detection Inter-Processor Communication Failed
DTC B1001B1001 00: Option Configuration Error B1001 45: Option Configuration Error Variant Not Programmed B1001 46: Option Configuration Error B1001 4B: Option Configuration Error Calibration Not Learned
DTC B101D (HP2 Air Conditioning Control Module)B101D XX: ECU Hardware
DTC B101D (except HP2 A/C Control Module)B101D XX: ECU Hardware
DTC B101EB101E XX: ECU Software
DTC B137AB137A 01: Hybrid Accessory Wake Up Circuit - Short to Battery B137A 06: Hybrid Accessory Wake Up Circuit - Short to Ground or Open
DTC B137BB137B 06: Accessory Power Module Wake Up Circuit - short to ground or open
DTC C0550C0550 00: Electronic Control Unit (ECU) Performance C0550 31: Electronic Control Unit (ECU) Performance C0550 32: ECU Performance General Memory Failure C0550 34: ECU Malfunction RAM Failure C0550 35: ECU Malfunction ROM Failure C0550 36: ECU Malfunction EEPROM Failure C0550 37: ECU Malfunction Watch Dog failure C0550 38: ECU Performance Supervision Software Failure C0550 39: ECU Performance Internal Electronic Failure/Discard C0550 4B: ECU Internal Fault
DTC C056DC056D XX: Electronic Control Unit Hardware
DTC C056EC056E XX: Electronic Control Unit Software
DTC C126C, C126D, C12E3, or U180FC126C: Control Module Communication Bus B Off C126D: Control Module Communication Bus B Off C12E3: Control Module Communication Bus B Off U180F: Control Module Communication Bus B Off
DTC U0020U0020 00: Low Speed CAN Communication Bus Performance
DTC U0073 or U2100U0073 00: Control Module Communication Bus Off U0073 71: ECU HS Bus Off U0073 72: ECU LS Bus Off U2100 00: Controller Area Network (CAN) Bus Communication U2100 47: Controller Area Network (CAN) Bus Communication
DTC U0074U0074 00: Control Module Communication Bus B Off
DTC U0100-U02FF (with HP2)U0100-U02FF (with HP2): Supervised message including transmitter module availability not received.
DTC U0100-U02FF (without HP2)U0100-U02FF (without HP2): Supervised message including transmitter module availability not received.
DTC U1500, U1511, U1512, or U1513U1500 01: Inter-Device Dedicated Bus 1 Short to Battery U1500 02: Inter-Device Dedicated Bus 1 Short to Ground U1500 31: Electronic Control Unit (ECU) Performance General Checksum Failure U1511 00: Inter-device Dedicated Bus Lost Communication With Device 1 U1512 00: Inter-device Dedicated Bus Lost Communication With Device 2
DTC U180FU180F: Control Module Communication Bus B Off
DTC U1812U1812 00: Battery Energy Control Module Bus B High Speed Communication Enable Circuit Low
DTC U1813U1813 00: Battery Energy Control Module Bus B High Speed Communication Enable Circuit High
DTC U1814U1814 00: Powertrain High Speed Communication Enable Circuit
DTC U1815U1815 00: Lost Communication With Drive Motor Control Module "A" on Bus "B"
DTC U1816U1816 00: Lost Communication With Drive Motor Control Module "B" on Bus "B"
DTC U1817U1817 00: Lost Communication With Hybrid Powertrain Control Module on Bus "B"
DTC U1818U1818 00: Lost Communication With ECM/PCM A on Bus B
DTC U1820U1820 00: Lost Communication with Brake System Control Module on Bus B
DTC U1821U1821 00: Lost Communication With DC to DC Converter Control Module A on Bus B
DTC U1826U1826 71: Lost Communication With Multi-Axis Acceleration Sensor Module on Bus "B" Invalid Data U1826 72: Lost Communication With Multi-Axis Acceleration Sensor Module on Bus "B" Message Counter Incorrect U1826 7F: Lost Communication With Multi-Axis Acceleration Sensor Module on Bus "B" Bus Signal Erratic
DTC U1829U1829 00: Lost Communication with Gateway A on Bus B
DTC U182AU182A 00: Lost Communication With Accessory Power Module
DTC U1842U1842: Lost Communication With ECM/PCM
DTC U1843U1843: Lost Communication With ECM/PCM
DTC U1862U1862 00: Battery Energy Control Module Lost Communication with Serial Data Gateway Module
DTC U1866U1866 00: Battery Energy Control Module Lost Communication With Body Control Module
DTC U186AU186A: Lost Communication With Transfer Case Control Module
DTC U186BU186B: Lost Communication With TCM
DTC U1875U1875 00: Drive Motor A Control Module Lost Communication With Battery Energy Control Module
DTC U1876U1876 00: Drive Motor Control Module A Lost Communication With Engine Control Module (ECM)
DTC U1878U1878 00: Drive Motor B Control Module Lost Communication With Battery Energy Control Module
DTC U1879U1879 00: Drive Motor Control Module B Lost Communication With Engine Control Module (ECM)
DTC U1885U1885 00: Battery Energy Control Module Lost Communication With Hybrid Powertrain Control Module
DTC U1886U1886 00: Battery Energy Control Module Lost Communication With Engine Control Module (ECM)/Powertrain Control Module (PCM)
DTC U1888U1888 00: Lost Communication with Battery Pack
DTC U189AU189A 00: DC to DC Converter Control Module A Lost Communication With Hybrid Powertrain Control Module
DTC U2099U2099 00: High Speed Communication Enable Circuit
DTC U209AU209A 00: High Speed Communication Enable Circuit Low
DTC U209DU209D 00: Battery Energy Control Module High Speed Communication Enable Circuit High
DTC U2100U2100 00: Controller Area Network (CAN) Bus Communication
DTC U2103U2103 00: Fewer Controllers On Than Programmed
DTC U2105-U2199U2142 00: Lost Communication With Yaw Rate Sensor (YRS)

DIAGNOSTIC CODE INDEX

Control Module U Code List

This list includes all Data Communications related U-code DTCs in alphanumeric order with descriptors for all modules. Not all DTCs listed will be applicable to all vehicles.

DTCDTC Descriptor
U0001 00High Speed CAN Bus Malfunction
U0002 00High Speed CAN Bus
U0010 00Medium Speed CAN Bus
U0020 00Low Speed CAN Bus
U0073 00Control Module Communication Bus A Off
U0073 71ECU HS Bus Off
U0073 72ECU LS Bus Off
U0074 00Control Module Communication Bus B Off
U0075 00Control Module Communication Bus C Off
U0100 00Lost Communication with Engine/Powertrain Control Module (ECM/PCM)
U0100 75Lost Communication with Engine/Powertrain Control Module (ECM)
U0100 7FLost Communication with Engine/Powertrain Control Module (ECM)
U0101 00Lost Communication with Transmission Control Module (TCM)
U0101 75Lost Communication with Transmission Control Module (TCM)
U0102 00Lost Communication with Transfer Case Control Module
U0104 00Lost Communication with Cruise Control Module
U0104 7FLost Communication with Cruise Control Module
U0106 00Lost Communication with Glow Plug Control Module
U0109 00Lost Communication with Fuel Pump Control Module
U010E 00Lost Communication with Reductant Sensor Module
U010F 00Lost Communication with Air Conditioning Control Module
U0111 00Lost Communication with Battery Energy Control Module
U0115 00Lost Communication with ECM/PCM B
U0117 00Lost Communication PTO Control Module
U0121 00Lost Communication with Electronic Brake Control Module (EBCM)
U0122 00Lost Communication with Vehicle Stability Control Module (ESCM)
U0123 00Lost Communication with Yaw Rate Sensor Module
U0126 00Lost Communication with Steering Wheel Angle Sensor Module
U0128 00Lost Communication with Park Brake Control Module
U0129 00Lost Communication with Brake System Control Module
U0131 00Lost Communication with Power Steering Control Module
U0132 00Lost Communication with Suspension Control Module
U0134 00Lost Communication with Power Steering Control Module - Rear
U0136 00Lost Communication with Differential Control Module - Rear
U0137 00Lost Communication with Trailer Brake Control Module
U0140 00Lost Communication with Body Control Module
U0141 00Lost Communication with Body Control Module A
U0144 00Lost Communication with Body Control Module D
U0146 00Lost Communication with Gateway A
U0151 00Lost Communication with Inflatable Restraint Sensing and Diagnostic Module (SDM)
U0151 71Lost Communication with Inflatable Restraint Sensing and Diagnostic Module (SDM) Invalid Serial Data Received
U0151 7FLost Communication with Restraints Control Inflatable Restraint Sensing and Diagnostic Module (SDM) Erratic
U0155 00Lost Communication with Instrument Panel Cluster (IPC) Control Module
U0156 00Lost Communication with Information Center A (DIC)
U0157 00Lost Communication with Information Center B (DID)
U0158 00Lost Communication with Head Up Display
U0159 00Lost Communication with Parking Assist Control Module (RPA)
U0160 00Lost Communication with Chime Alarm Control Module
U0164 00Lost Communication with HVAC Control Module
U0165 00Loss of Communication with HVAC Control Module - Rear
U0166 00Lost Communication with Auxiliary Heater Control Module
U0168 00Lost Communication with Vehicle Security Control Module
U0170 00Lost Communication with Restraints System Sensor A (PPS)
U0172 00Lost Communication with Restraints System Sensor C
U0173 00Lost Communication with Restraints System Sensor D
U0181 00Lost Communication with Headlamp Leveling Control Module
U0184 00Lost Communication with Radio
U0186 00Lost Communication with Audio Amplifier
U0191 00Lost Communication with Television
U0194 00Lost Communication with Digital Radio Receiver (DRR)
U0196 00Lost Communication with Rear Audio Control Module
U0198 00Lost Communication with Telematic Control Module
U0199 00Lost Communication with Driver Door Control Module
U0200 00Lost Communication with Door Control Module
U0208 00Lost Communication with Seat Control Module A (DSM/MSM)
U0209 00Lost Communication with Seat Control Module B (HVSM)
U0210 00Lost Communication with Seat Control Module C (RHSM)
U0214 00Lost Communication with Remote Function Actuation
U0230 00Lost Communication with Rear Gate Module
U0232 00Lost Communication with Side Object Detection (SOD) Module - Left
U0233 00Lost Communication with Side Object Detection (SOD) Module - Right
U0236 00Lost Communication with Column Locking Module (CLM)
U023A 00Lost Communication with Vehicle Direction Camera Control Module (Lane Departure Warning)
U0241 00Lost Communication with Headlamp Control Module A
U0249 00Loss of Communication with Entertainment Control Module - Rear B
U0252 00Lost Communication with Trailer Interface Module
U0255 00Loss of Communication with Front Display Interface Module
U0256 00Loss of Communication with Front Controls Interface Module
U0257 00Loss of Communication with Front Controls/Display Interface Module
U0293 00Lost Communication with HP2 Powertrain Control Module
U029D 00Lost Communication with NOX Sensor Module 1
U029E 00Lost Communication with NOX Sensor Module 2
U0401 00Invalid Data Received From ECM
U0401 72Invalid Data Received From ECM Message Counter Incorrect
U0401 74Invalid Data Received From ECM Bus Signal Checksum Error
U0402 72Invalid Data Received From Transmission Control Module Message Counter Incorrect
U0402 73Invalid Data Received From Transmission Control Module Parity Error
U0402 74Invalid Data Received From Transmission Control Module Bus Signal Checksum Error
U0405 00Invalid Data Received From Cruise Module
U0405 71Invalid Data Received From Cruise Control Module Invalid Data
U0405 72Invalid Data Received From Cruise Control Module Message Counter Incorrect
U0405 74Invalid Data Received From Cruise Control Module Bus Signal Checksum Error
U0415 00Invalid Data Received From Electronic Brake Control Module
U0415 72Invalid Data Received From Electronic Brake Control Module Message Counter Incorrect
U0415 74Invalid Data Received From Electronic Brake Control Module Bus Signal Checksum Error
U0416 00Invalid Data Received From Vehicle Dynamics Control Module
U0416 72Invalid Data Received From Vehicle Dynamics Control Module Message Counter Incorrect
U0416 74Invalid Data Received From Vehicle Dynamics Control Module Bus Signal Checksum Error
U0418 00Invalid Data Received From Brake System Control Module
U0418 71Invalid Data Received From Brake System Control Module Invalid Data
U0418 72Invalid Data Received From Brake System Control Module Message Counter Incorrect
U0422 00Invalid Data Received From Body Control Module
U0422 70Invalid Data Received From Body Control Module
U0422 72Invalid Data Received From Body Control Module Message Counter Incorrect
U0422 74Invalid Data Received From Body Control Module Bus Signal Checksum Error
U0424 00Invalid Data Received From HVAC Control Module
U0432 00Invalid Data Received From Multi-Axis Acceleration Sensor Module
U0432 72Invalid Data Received From Multi-Axis Acceleration Sensor Module Message Counter Incorrect
U0432 74Invalid Data Received From Multi-Axis Acceleration Sensor Module Bus Signal Checksum Error
U0438 71Invalid Data Received From Trailer Brake Control Module
U0465 00Invalid Data Received From Power Take-Off Control Module
U180FElectronic Brake Control Module Communications Bus B OFF
U1000Class 2 Data Link Malfunction
U1016Lost Communication with ECM/PCM
U1017Lost Communication with Engine Control System
U1024Lost Communication with Transmission Control Module
U1026Lost Communication with Transfer Case Control Module
U1040Lost Communication with Electronic Brake Control Module
U1041Lost Communication with Electronic Brake Control Module
U1064Lost Communication with Body Control Module/Dash Integration Module
U1088Lost Communication with Inflatable Restraint Sensing and Diagnostic Module
U1096Lost Communication with Instrument Panel Cluster
U1098Lost Communication with Secondary Information Center
U1099Lost Communication with Head Up Display
U1100Lost Communication with Driver Information and Displays Control System
U1128Lost Communication with Radio
U1129Lost Communication with Amplifier
U1133Lost Communication with Mini Disc Changer
U1137Lost Communication with Satellite Digital Audio Reception System (DRR)
U1153Lost Communication with Climate Control Panel
U1162Lost Communication with Liftgate Module
U1164Lost Communication with Driver Door Switch
U1165Lost Communication with Passenger Door Switch
U1176Lost Communication with Remote Function Actuation
U1177Lost Communication with Folding Top Controller
U1192Lost Communication with Immobilizer
U1193Lost Communication with Remote Control Door Lock Receiver
U1255Loss of Class 2 Communication
U1300Class 2 Data Link Low
U1301Class 2 Data Link High
U1305Class 2 Data Link High or Low
U1500 00Inter Device Dedicated Bus
U1500 00(EBCM) Inter Device Dedicated Bus (Lost Communication with Yaw and Lateral Accelerometer Sensor)
U1500 00(DDM/PDM) Inter Device Dedicated Bus (Lost Communication with Front Window Motor)
U1500 01Inter-Device Dedicated Bus Short to Battery
U1500 02Inter-Device Dedicated Bus Short to Ground
U1511 00(BCM) Inter-device Dedicated Bus 1 Lost Communication with Device 1 (Electronic Compass Module)
U1511 00(DDM/PDM) Inter-device Dedicated Bus 1 Lost Communication with Device 1 (Front Window Motor)
U1511 00(HCM) Inter-device Dedicated Bus 1 Lost Communication with Device 1 (AFL - Left)
U1512 00(DDM) Inter-device Dedicated Bus 1 Lost Communication with Device 2 (Left Rear Window Motor)
U1513 00(PDM) Inter-device Dedicated Bus 1 Lost Communication with Device 3 (Right Rear Window Motor)
U1521 00(HCM) Inter-device Dedicated Bus 2 Lost Communication with Device 1 (AFL - Right)
U1650 00Chassis System Dedicated Bus Controller
U1651 00Chassis System Dedicated Bus Sensor
U180F 00Control Module Communication Bus B Off
U1802 00Lost Communication with Fuel Pump Control Module
U1812 00Battery Energy Control Module Bus B High Speed Communication Enable Circuit Low
U1813 00Battery Energy Control Module Bus B High Speed Communication Enable Circuit High
U1814 00Powertrain High Speed Communication Enable Circuit
U1815 00Lost Communication with Drive Motor Control Module A on Bus B
U1816 00Lost Communication with Drive Motor Control Module B on Bus B
U1817 00Lost Communication with Hybrid Powertrain Control Module on Bus B
U1818 00Lost Communication with ECM/PCM A on Bus B
U1820 00Lost Communication with Brake System Control Module on Bus B
U1821 00Lost Communication with DC to DC Converter Control Module A on Bus B
U1822 00Lost Communications with Power Steering Control Module on Bus B
U1823 00Lost Communications with Cruise Control Module on Bus B
U1824 00Lost Communications with Suspension Control Module
U1825 00Lost Communications with Vehicle Dynamics Control Module
U1826 71Lost Communication with Multi-Axis Acceleration Sensor Module on Bus B Invalid Serial Data Received
U1826 72Lost Communication with Multi-Axis Acceleration Sensor Module on Bus B Alive Counter Incorrect/Not Updated
U1826 7FLost Communication with Multi-Axis Acceleration Sensor Module on Bus B Erratic
U1827 71Lost Communication with Steering Angle Sensor Module on Bus B Invalid Serial Data
U1827 72Lost Communication with Steering Angle Sensor Module on Bus B Alive Counter Incorrect/Not Updated
U1827 74Lost Communication with Steering Angle Sensor Module on Bus B Value of Signal Protection Calculation Incorrect
U1827 7FLost Communication with Steering Angle Sensor Module on Bus B Erratic
U1829 00Lost Communication with Gateway A on Bus B
U182A 00Lost Communication with Battery Energy Control Module on Bus B
U1842 00Electronic Brake Control Module Lost Communication with Engine Control Module on Bus B
U1843 00Electronic Brake Control Module Lost Communication with Hybrid Engine Control Module on Bus B
U1862 00Battery Energy Control Module Lost Communication with Communications Gateway Module
U1863 00Starter/Generator Control Module Lost Communication with Body Control Module
U1865 00Fuel Operated Heater Lost Communication with Engine Control Module
U1866 00Battery Energy Control Module Lost Communication with Body Control Module
U186A 00Lost Communication with Transfer Case Control Module
U186B 00Lost Communication with TCM
U1875 00Drive Motor A Control Module Lost Communication with Battery Energy Control Module
U1876 00Drive Motor A Control Module Lost Communication with Engine Control Module (ECM)/Powertrain Control Module (PCM)
U1878 00Drive Motor B Control Module Lost Communication with Battery Energy Control Module
U1879 00Drive Motor B Control Module Lost Communication with Engine Control Module (ECM)/Powertrain Control Module (PCM)
U1885 00Battery Energy Control Module Lost Communication with HP2 Powertrain Control Module
U1886 00Battery Energy Control Module Lost Communication with Engine Control Module (ECM)
U1888 00Hybrid Powertrain Control Module Lost Communication With Starter/Generator Control Module
U1897 00Starter/Generator Control Module Lost Communication with Battery Energy Control Module
U1899 00Starter/Generator Control Module Lost Communication with Engine Control Module/Powertrain Control Module
U189A 00DC to DC Converter Control Module A Lost Communication with HP2 Powertrain Control Module
U2099 00High Speed Communication Enable Circuit
U209A 00High Speed Communication Enable Circuit Low
U209D 00Battery Energy Control Module High Speed Communication Enable Circuit High
U2100 00Controller Area Network (CAN) Bus Communication
U2100 47Controller Area Network (CAN) Bus Communication
U2102 00More Controllers On Bus Than Programmed
U2103 00Fewer Controllers On Bus Than Programmed
U2105 00Lost Communication with Engine Control Module
U2106 00Lost Communication with Transmission Control Module
U2107 00Lost Communication with Body Control Module
U2108 00Lost Communication with ABS/TCS Control System
U2109 00Lost Communication with Powertrain Control Module
U2110 00Lost Communication with Chassis Multiple Control System
U2111 00Lost Communication with Steering Control Module
U2112 00Lost Communication with Electronic Suspension Control (ESC)
U2113 00Lost Communication with Sensing and Diagnostic Module (SDM)
U2114 00Lost Communication with PPS or CPS
U2115 00Lost Communication with Restraints Control System
U2116 00Lost Communication with Instrument Cluster
U2117 00Lost Communication with Info Display
U2118 00Lost Communication with Head Up Display (HUD)
U2119 00Lost Communication with Daytime Running Lamps Control Module
U2120 00Lost Communication with Automatic Headlamp Leveling Control Module
U2121 00Lost Communication with Radio Display
U2122 00Lost Communication with Radio
U2123 00Lost Communication with Compact Disc Changer (CDX)
U2124 00Lost Communication with Audio Amplifier
U2125 00Lost Communication with Telematic Unit
U2126 00Lost Communication with Mobile Communications Control System
U2127 00Lost Communication with Front HVAC Control Module
U2128 00Lost Communication with Rear HVAC Control Module
U2129 00Lost Communication with Remote Function Actuator (RFA)
U2130 00Lost Communication with Driver Door Module (DDM)
U2131 00Lost Communication with Driver Seat Module (DSM)
U2132 00Lost Communication with Passenger Door Module (PDM)
U2133 00Lost Communication with Passenger Seat Module (PSM)
U2134 00Lost Communication with Rear Door Module (RDM)
U2135 00Lost Communication with Rear Integration Module (RIM)
U2136 00Lost Communication with Memory Mirror Module (MMM)
U2137 00Lost Communication with Vehicle Theft Deterrent (VTD)
U2138 00Lost Communication with Column Locking Module (CLM)
U2139 00Lost Communication with Column Integration Module (CIM)
U2140 00Lost Communication with Underhood Electrical Center (UEC)
U2141 00Lost Communication with Rear Electrical Center
U2142 00Lost Communication with Yaw Rate Sensor (YRS)
U2143 00Lost Communication with Steering Angle Sensor (SAS)
U2144 00Lost Communication with Distance Sensing Cruise Control Module
U2145 00Lost Communication with Parking Assistance System (PAS)
U2146 00Lost Communication with Shift Lever Module (SLM)
U2147 00Lost Communication with Auxiliary Heater System (AHS)
U2148 00Lost Communication with Sun Roof Module (SRM)
U2149 00Lost Communication with Tire Pressure Monitor (TPM) System
U2150 00Navigation Electronic Control Unit (ECU) Gateway Communications
U2151 00Navigation Electronic Control Unit (ECU) Communications
U2152 00Navigation Bus Request Line Circuit Low
U2153 00Navigation Electronic Control Unit (ECU) - VICS Communication Circuit
U2160 00Lost Communication with Steering Control System Sensor
U2161 00Lost Communication with Dash Integration Module (DIM)
U2162 00Lost Communication with Instrument Panel integration Module (IPM)
U2163 00Lost Communication with Left Rear Door Module (LRDM)
U2164 00Lost Communication with Right Rear Door Module (RRDM)
U2165 00Lost Communication with Driver Door Switch (DDS)
U2166 00Lost Communication with Driver Position Module (DPM)
U2167 00Lost Communication with Remote Control Door Lock Receiver (RCDLR)
U2168 00Lost Communication with Side Object Detection (SOD) Module - Left
U2169 00Lost Communication with Side Object Detection (SOD) Module - Right
U2170 00Lost Communication with Four Wheel Drive (4WD) Clutch
U2171 00Lost Communication with Rear Seat Entertainment (RSE)
U2172 00Lost Communication with Digital Radio Receiver (DRR)
U2173 00Lost Communication with Passive Entry and Passive Start System
U2174 00Lost Communication with Parking Heater System
U2175 00Lost Communication with Special Vehicle Module
U2176 00Lost Communication with Power Take Off (PTO) Control Module
U2177 00Lost Communication with Cruise Control Module
U2178 00Lost Communication with Trailer Interface Module
U2179 00Lost Communication with Television Module
U2180 00Lost Communication with Folding Top Control Module
U2181 00Lost Communication with Moveable Roof Module

Diagnostic Instructions

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit/System Description

The internal fault detection is handled inside the control module. No external circuits are involved.

Conditions for Running the DTC

The module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

Conditions for Setting the DTC

The module has detected an internal malfunction.

Action Taken When the DTC Sets

The module refuses all additional inputs.

Conditions for Clearing the DTC

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 100, without a repeat of the malfunction.

Diagnostic Aids

  1. This DTC may be stored as a history DTC without affecting the operation of the control module.
  2. Do not replace a control module based only on DTC B1000 being set in history with the exception of the following control modules: Sensing and Diagnostic Module (SDM) Rollover Sensor Passenger Presence System Module
  3. If DTC B1000 is set as current, replace the appropriate control module.

Circuit/System Verification

If the DTC is set, replace the appropriate control module.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Some control modules must be configured with serial numbers, vehicle options, or other information. If a control module was not properly configured after installation, that module may set DTC B1001.

Battery voltage is between 9-16 volts and data link communications operate normally.

The control module is not configured properly.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
  1. Program or configure the module or related module that set DTC B1001. The module should successfully configure. If the module will not configure, replace the module that set the DTC.
  2. With a scan tool, clear the DTC.
  3. Ignition OFF, remove the scan tool, open and close the drivers door.
  4. Wait 60 seconds, then recheck for DTCs. DTC B1001 should not set. If DTC B1001 sets, replace the module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The internal fault detection is handled inside the control module. The symptom byte listed in the DTC Descriptor is for engineering reference only. No external circuit diagnosis is involved.

The control module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage, high voltage, and ground. This program runs even if the voltage is out of the valid operating range.

The control module has detected an internal malfunction.

The control module refuses all additional inputs.

The DTC can only be cleared with a scan tool.

Verify that DTC B101D is not set.

  1. If the DTC is set, reprogram the control module with the most current software. If the DTC resets, replace the control module that set the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic repair.

Control Module References for control module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The internal fault detection is handled inside the control module. The symptom byte listed in the DTC Descriptor is for engineering reference only. No external circuit diagnosis is involved.

The control module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

The control module has detected an internal malfunction.

The control module refuses all additional inputs.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the control module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. This DTC may be stored as a history DTC without affecting the operation of the control module.
  2. Do not replace a control module based only on DTC B101D being set in history with the exception of the following control modules: Sensing and Diagnostic Module (SDM) Passenger Presence System Module
  3. If DTC B101D is set as current, replace the appropriate control module.

Verify that DTC B101D is not set.

  1. If the DTC is set, replace the control module that set the DTC.

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for control module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Some control modules must be configured with specific software, serial numbers, vehicle options, or other information. If a control module was not properly configured after installation that module may set DTC B101E. The symptom byte listed in the DTC Descriptor is for engineering reference only. No external circuit diagnosis is involved.

Battery voltage is between 9-16 V and data link communications operate normally.

The control module is not configured properly.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Reference Information

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool References

Control Module References for scan tool information

Verify DTC B101E is not set.

  1. If the DTC is set, program the control module. If the DTC resets, replace the control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Wake Up SignalB137A 06, *U1812*U1812B137A 01, *U1813
* Sets in the HPCM

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The wake up signal circuit is energized by the serial data gateway (SDG) module to activate the drive motor generator power inverter module (PIM) and the drive motor generator battery control module. If the wake up signal is not responded to by all three modules, this DTC sets in the SDG module.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur.

A short circuit exists on the wake up signal circuit of the SDG module.

The malfunction indicator lamp (MIL) illuminates and the driver information center (DIC) displays the message Service Hybrid System.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Hybrid Controls Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#hybrid-engine-controls-wiring-schematics)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

  1. EL-48569 Terminal Covers
  2. EL-48900 HEV Safety Kit

Circuit/System Testing

WARNINGAlways perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed. The High Voltage Disabling procedure will perform the following tasks: Identify how to disable high voltage. Identify how to test for the presence of high voltage. Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed. Failure to follow the procedures exactly as written may result in serious injury or death.
  1. Perform the «High Voltage Disabling»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system__high-voltage-disabling) procedure.
  2. Reconnect the 12-volt battery.
  3. Ignition OFF, disconnect harness connector X1 of the drive motor generator battery control module and the PIM.
  4. Ignition ON, verify that a test lamp illuminates between the wake up signal circuit of the PIM and ground, and the drive motor generator battery control module and ground as follows: PIM X1 19 BECM X1 12 If the test lamp does not illuminate, test the circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the SDG module.
  5. Ignition OFF, verify that a test lamp does not illuminate between the PIM wake up signal circuit terminal 19 and ground. If the test lamp illuminates, test the circuit for a short to voltage. If the circuit tests normal, replace the SDG module.
  6. If all circuits test normal, replace the SDG module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Wake Up SignalB137B 06U182AU189A

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The wake up signal circuit is energized by the serial data gateway module (SDGM) to activate the accessory DC power control module (APM) immediately when the body control module (BCM) signals the SDGM that serial data is required.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur.

The wake up signal circuit is shorted to ground.

The module is never signaled and the charging system will not operate. The battery indicator will illuminate along with multiple driver information messages.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

With a scan tool, verify that DTC U182A is not set in the SDGM, and U189A is not set in the HPCM.

  1. If either DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  1. Ignition OFF, disconnect the harness connector X1 at the APM.
  2. Ignition ON, verify that a test lamp illuminates between the wake up signal circuit terminal 3 and ground. If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance.
  3. Ignition OFF and scan tool disconnected, verify that a test lamp does not illuminate between the signal circuit terminal 3 and ground. If the test lamp illuminates, test the circuit for a short to voltage.
  4. If all circuits test normal, replace the APM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

When the ignition is turned ON, the microprocessor runs a diagnostic program to detect an internal fault when power up is commanded. If an internal malfunction is detected, the control module will store a DTC C0550 in its memory.

The microprocessor runs a diagnostic program to detect an internal fault when power up is commanded. The only requirements are voltage and ground.

  1. The control module detects an internal write malfunction.
  2. The control module detects an internal checksum malfunction.
  1. The affected system warning indicator/warning message will activate.
  2. The affected system will be disabled.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the control module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
  1. With a scan tool, clear DTC C0550. The DTC should clear. If the DTC will not clear, replace the control module.
  2. Ignition OFF, remove the scan tool, open and close the drivers door.
  3. Wait 60 seconds, ignition ON, then recheck for DTCs. DTC C0550 should not set. If DTC C0550 sets, replace the module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The internal fault detection is handled inside the control module. The symptom byte listed in the DTC Descriptor is for engineering reference only. No external circuit diagnosis is involved.

The module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

The module has detected an internal malfunction.

The module refuses all additional inputs.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. This DTC may be stored as a history DTC without affecting the operation of the module.
  2. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
  3. If this DTC is retrieved as both a current and history DTC, replace the module that set the DTC.

Verify that DTC C056D is not set.

  1. If the DTC is set, program the control module. If the DTC resets, replace the control module that set the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Some control modules must be configured with specific software, serial numbers, vehicle options, or other information. If a control module was not properly configured after installation that module may set DTC C056E. The symptom byte listed in the DTC Descriptor is for engineering reference only. No external circuit diagnosis is involved.

Battery voltage is between 9-16 V and data link communications operate normally.

The control module is not configured properly.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool References

Control Module References for scan tool information

Verify DTC C056E is not set.

  1. If the DTC is set, program the control module. If the DTC resets, replace the control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for control module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The PTLAN serial data circuits are serial data buses used to communicate information between the control modules. The PTLAN serial data circuits also connect directly to the data link connector (DLC) for programming purposes. If this serial data system is inoperative the modules will still communicate with the scan tool due to other serial data systems but not with each other. Communication with the scan tool for the modules on the PTLAN bus is through the serial data gateway module (SDGM) on the HSGMLAN serial data system.

Conditions for Running the DTCs

  1. Supply voltage to the modules are in the normal operating range.
  2. The ignition switch in any position other than START.

The module setting the DTC has attempted to establish communications on the PTLAN serial data circuits more than 3 times.

Action Taken When the DTCs Sets

  1. The module suspends all message transmission.
  2. The MIL and battery indicators will illuminate, along with several DIC messages.
  3. The vehicle may continue to run for several minutes, then will stall and not start.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Verify that DTC U0074 is not set.

  1. If the DTC is set, refer to «DTC U0074»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Modules connected to the GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have programmed information about what messages are needed to be exchanged on the serial data circuits. The messages are also supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module.

DTC U0020 will set when fewer modules are detected on the bus before the modules can learn the other modules IDs. If the communication bus is opened, or if the modules power supply is lost when the vehicle is in the OFF power mode, and then placed in the RUN power mode, U0020 will set in specific modules.

  1. Voltage at the modules is in the normal operating voltage range.
  2. The vehicle power mode requires serial data communication to occur.
  3. The DTC U2100 does not have a current status.

A supervised periodic message that includes the transmitter module availability has not been received.

The module uses a default value for the missing parameter.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Diagnosis of this DTC is accomplished via the symptom, DTC U0100-U02FF (with HP2) or DTC U0100-U02FF (without HP2) .

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The serial data circuits are serial data buses are used to communicate information between the control modules. The serial data circuits also connect directly to the data link connector (DLC).

  1. Supply voltage at the control modules are in the normal operating range.
  2. The vehicle power mode requires serial data communications.

The control module setting the DTC has attempted to establish communications on the serial data circuits more than 3 times in 5 seconds.

  1. The module suspends all message transmission.
  2. The module uses default values for all parameters received on the serial data circuits.
  3. In the TCM, DTC U0073 will cause the transmission to go into default gears.
  4. In the ECM and TCM, DTC U0073 will cause the malfunction indicator lamp (MIL) to illuminate.
  5. The module inhibits the setting of all other communication DTCs.
  1. The ECM/TCM modules turn OFF the MIL after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
  2. A current DTC clears when the malfunction is no longer present.
  3. A history DTC clears when the control module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. Refer to «Data Link References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system__data-link-references) to determine which serial data system is used for a specific control module.
  2. This DTC cannot be retrieved with a current status. Diagnosis is accomplished using the symptom «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «Scan Tool Does Not Communicate with Low Speed GMLAN Device»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Powertrain High Speed GMLAN Serial Data (+)U0074U0074, U0100-U0299*U0074
Powertrain High Speed GMLAN Serial Data (-)U0074U0074, U0100-U0299*U0074

The PTLAN serial data circuits are serial data buses used to communicate information between the control modules. The PTLAN serial data circuits also connect directly to the data link connector (DLC) for programming purposes. If this serial data system is inoperative the modules will still communicate with the scan tool due to other serial data systems but not with each other. Communication with the scan tool for the modules on the PTLAN bus is through the serial data gateway module (SDGM) on the HSGMLAN serial data system.

  1. Supply voltage to the modules are in the normal operating range.
  2. The ignition switch in any position other than START.

The module setting the DTC has attempted to establish communications on the PTLAN serial data circuits more than 3 times.

  1. The module suspends all message transmission.
  2. The MIL and battery indicators will illuminate, along with several DIC messages.
  3. The vehicle may continue to run for several minutes, then will stall and not start.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
  1. Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated "current" or "active" status. Loss-of- communication U-codes such as these can set for a variety of reasons. Many times, they're transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios: A control module on the data communication circuit was disconnected while the communication circuit is awake. Power to one or more modules was interrupted during diagnosis A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold. Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialize at the same time. If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.
  2. Do not replace a control module reporting a U code. The U code identifies which control module needs to be diagnosed for a communication issue.
  3. Communication may be available between the BCM and the scan tool with the Powertrain High Speed GMLAN serial data system inoperative. This condition is due to the BCM using both the high and low speed GMLAN systems.
  4. The engine will not start when there is a total malfunction of the Powertrain High Speed GMLAN serial data bus.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Note. Each control module may need to be disconnected to isolate a circuit fault. Use the schematic to identify the following: Control modules the vehicle is equipped with Powertrain High Speed GMLAN serial data circuit terminating resistors Control module locations on the Powertrain High Speed GMLAN serial data circuits Each control module's Powertrain High Speed GMLAN serial data circuit terminals

  1. Attempt to communicate with all control modules on the Powertrain High Speed GMLAN serial data circuit. Communications should not be available with two or more control modules on the Powertrain High Speed GMLAN serial data circuit. If only one control module is not communicating, diagnose that control module only.
  2. Disconnect the scan tool from the DLC. The following tests will be done at the DLC connector.
  3. Ignition ON, test for less than 4.5 V between the serial data circuits listed below and ground: Terminal 3 Terminal 11 If greater than the specified range, test the serial data circuit for a short to voltage; refer to Testing the Serial Data Circuits for a Short to Voltage.
  4. Ignition OFF for 60 seconds, test for greater than 100 ohms between the serial data circuit listed below and ground: Terminal 3 Terminal 11 If not the specified value, test the serial data circuit for a short to ground; refer to Testing the Serial Data Circuits for a Short to ground.
  5. Test for 50-70 ohms between the serial data circuit terminal 3 and terminal 11. If less than 35 ohms, test for a short between the serial data circuits; refer to Testing the Serial Data Circuits for a Short between the Circuits. If 35-50 ohms there may be a third terminating resistor between the serial data circuits. This can happen if the incorrect control module is installed. Some control modules are available with and without the terminating resistors installed to reduce the need of terminating resistors in the wiring harness. If greater than 70 ohms but less than infinite, test the serial data circuit for an open/high resistance; refer to Testing the Serial Data Circuits for an Open/High Resistance. If infinite, test the serial data circuits between the DLC and the first connection to the serial data circuit for an open/high resistance.

Testing the Serial Data Circuits for a Short to Voltage

  1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control module.
  2. Ignition ON, test for greater than 4.5 V between each serial data circuit at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are greater than 4.5 V. If all serial data circuits are less than the specified range, replace the control module that was disconnected.
  3. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of the circuit shorted to voltage.
  4. Ignition ON, test for greater than 4.5 V between the serial data circuits at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are greater than 4.5 V. If all serial data circuits are less than the specified range, replace the control module that was just disconnected.
  5. Repeat step 3 until one of the follow conditions are isolated: A short to voltage on the serial data circuit between 2 control modules A short to voltage on the serial data circuit between a control module and a terminating resistor.

Testing the Serial Data Circuits for a Short to Ground

  1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control module.
  2. Ignition OFF for 60 seconds, test for less than 1k ohms between each serial data circuit at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are less than 1k ohms. If all serial data circuits are greater than the specified range, replace the control module that was disconnected.
  3. Disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of the circuit shorted to ground.
  4. Ignition OFF for 60 seconds, test for less than 1k ohms between the serial data circuits at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are less than 1k ohms. If greater than the specified range for all serial data circuits, replace the control module that was just disconnected.
  5. Repeat step 3 until one of the follow conditions are isolated: A short to ground on the serial data circuit between 2 control modules A short to ground on the serial data circuit between a control module and a terminating resistor.

Testing the Serial Data Circuits for a Short between the Circuits

  1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control module that is not communicating.
  2. Ignition OFF for 60 seconds, test for less than 35 ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 ohms. If each pair of serial data circuits is greater than the specified range, replace the control module that was disconnected.
  3. Connect the harness connectors at the control module that was disconnected.
  4. Disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of the circuits shorted together.
  5. Ignition OFF for 60 seconds, test for less than 35 ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 ohms. If each pair of serial data circuits is within the specified range, replace the control module that was just disconnected.
  6. Repeat step 3 until one of the following conditions are isolated: Serial data circuits shorted together between 2 control modules Serial data circuits shorted together between a control module and a terminating resistor A shorted terminating resistor

Testing the Serial Data Circuits for an Open/High Resistance

  1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control module that is not communicating.
  2. Ignition OFF for 60 seconds, test for greater than 100k ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are greater than 100k ohms. If each pair of serial data circuits is less than the specified range, replace the control module that was disconnected.
  3. Connect the harness connectors at the control module that was disconnected.
  4. Disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of the open circuit.
  5. Ignition OFF for 60 seconds, test for greater than 100k ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are greater than 100k ohms. If each pair of serial data circuits is less than the specified range, replace the control module that was just disconnected.
  6. Repeat step 3 until one of the following conditions are isolated: An open/high resistance on the serial data circuit between 2 control modules An open/high resistance on the serial data circuit between a control module and a terminating resistor An open/high resistance terminating resistor

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

DTC Descriptor

CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Module B+U0100-U02FFU0100-U02FF
Module IgnitionU0100-U02FFU0100-U02FF
Module GroundU0100-U02FFU0100-U02FF
Accessory Wake Up Serial DataU1814U0100-U02FF
High Speed GMLAN Serial Data Wake UpU2099U0100-U02FF
High Speed GMLAN Serial Data (+)2U0100-U02FF2
High Speed GMLAN Serial Data (-)2U0100-U02FF2
Low Speed GMLAN Serial Data1U0100-U02FF1
1. Scan tool does not communicate with low speed GMLAN device 2. Scan tool does not communicate with high speed GMLAN device

The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health (SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more control modules may set the same exact code. A loss of serial data communications DTC does not represent a failure of the control modules that contain the stored code.

The system voltage is between 9-16 V.

A supervised periodic message that includes the transmitter module availability has not been received.

  1. Specific subsystems will not function.
  2. DTC U0100 in the TCM will cause the transmission to go into default gears.
  3. Both DTC U0100 in the TCM and DTC U0101 in the ECM will cause the malfunction indicator lamp (MIL) to illuminate.
  1. The ECM/TCM turns OFF the MIL after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
  2. A current DTC clears when the malfunction is no longer present.
  3. A history DTC clears when the control module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated "current" or "active" status. Loss-of- communication U-codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios: A control module on the data communication circuit was disconnected while the communication circuit is awake. Power to one or more control modules was interrupted during diagnosis. A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold. Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialize at the same time. If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.
  2. A control module may have a U-code stored in history that does not require any repairs. Issues with late or corrupted messages between control modules can be temporary with no apparent symptom or complaint; this does not mean the control module is faulty. Do not replace a control module based only on a history U-code.
  3. Do not replace a control module reporting a U-code. The U-code identifies which control module needs to be diagnosed for a communication issue.
  4. Communication may be available between the BCM and the scan tool with either the low or high speed GMLAN serial data system inoperative. This condition is due to the BCM using both the low and high speed GMLAN systems.
  5. Use «Data Link References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system__data-link-references) to determine if the control module uses high or low speed GMLAN serial data communications.
  6. Some control modules may not have internal protection for specific control circuits and may open a B+ or ignition fuse. If a fuse is open and the B+ or ignition circuit is not shorted to ground, ensure none of the control circuits are shorted to ground before replacing the control module.
  7. This diagnostic can be used for any control module that is not communicating, regardless of the type of serial data circuit it is connected to, providing the vehicle is equipped with the control module.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Verify that DTC U1814, U2099, B1428, B1370, B1380, B1440, or B1441 is not set.

  1. If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
WARNINGAlways perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed. The High Voltage Disabling procedure will perform the following tasks: Identify how to disable high voltage. Identify how to test for the presence of high voltage. Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed. Before working on any high voltage system, be sure to wear the following Personal Protection Equipment: Safety glasses with appropriate side shields when within 50 feet of the vehicle, either indoors or outdoors. Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors. Visually and functionally inspect the gloves before use. Wear the Insulation gloves at all times when working with the high voltage battery assembly, whether the system is energized or not. Failure to follow the procedures exactly as written may result in serious injury or death.

Note. Use the schematic to identify the following: Control modules the vehicle is equipped with Control module locations on the low and high speed GMLAN serial data circuits The control modules B+, ignition, ground, communication enable and serial data circuit terminals

  1. Determine the control module that is not communicating. Refer to «Control Module U Code List»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system__control-module-u-code-list) .
  2. Using the Hybrid High Voltage Module Chart below, verify that the non-communicating control module is not a high voltage module. If the control module is a high voltage module, perform the «High Voltage Disabling»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system__high-voltage-disabling) procedure before proceeding with this diagnostic.
  3. If high voltage disabling is required, reconnect the 12 V battery after performing the high voltage disabling procedure.
  4. Ignition OFF, disconnect the harness connector of the control module that is not communicating.
  5. Test for less than 10 ohms between each ground circuit terminal and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  6. If equipped, verify that a test lamp illuminates between each B+ circuit terminal and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
  7. If equipped, ignition ON, verify that a test lamp illuminates between each ignition circuit terminal and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
  8. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup circuit terminal and ground. If the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
  9. Ignition OFF for 60 seconds, test for less than 5 ohms between the serial data circuit terminals and the appropriate DLC terminal listed below: Class 2 serial data circuit terminal 2 Low speed GMLAN serial data terminal 1 High speed GMLAN serial data terminal 6 or 14 If greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module and a control module setting the DTC or a serial data splice pack.
  10. If all circuits test normal, replace the control module that is not communicating.
ModuleVoltage SystemData Link Type
Drive Motor Generator Power Inverter Module (PIM) (Includes Drive Motor Control Module (MCM) 1, 2 and Hybrid Powertrain Control Module (HPCM)300 V 12 VHigh Speed Hybrid GMLAN High Speed GMLAN
Accessory DC Power Control Module (APM)300 V 42 V 12 VHigh Speed Hybrid GMLAN
Transmission Control Module (TCM) (RPO M99)300 V 12 VHigh Speed GMLAN
Air Conditioning Control Module (ACCM) (Part of AC Compressor with HP2)300 V 12 VLow Speed GMLAN
Drive Motor Generator Battery Control Module (BECM)300 V 12 VHigh Speed GMLAN
Power Steering Control Module (PSCM)42 V 12 VHigh Speed GMLAN

Hybrid High Voltage Module Chart

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Module B+U0100-U02FFU0100-U02FF
Module IgnitionU0100-U02FFU0100-U02FF
Module GroundU0100-U02FFU0100-U02FF
Accessory Wake Up Serial DataU1814U0100-U02FF
High Speed GMLAN Serial Data Wake UpU2099U0100-U02FF
High Speed GMLAN Serial Data (+)2U0100-U02FF2
High Speed GMLAN Serial Data (-)2U0100-U02FF2
Low Speed GMLAN Serial Data1U0100-U02FF1
1. Scan tool does not communicate with low speed GMLAN device 2. Scan tool does not communicate with high speed GMLAN device

The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health (SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more control modules may set the same exact code. A loss of serial data communications DTC does not represent a failure of the control modules that contain the stored code.

The system voltage is between 9-16 V.

A supervised periodic message that includes the transmitter module availability has not been received.

  1. Specific subsystems will not function.
  2. DTC U0100 in the TCM will cause the transmission to go into default gears.
  3. Both DTC U0100 in the TCM and DTC U0101 in the ECM will cause the malfunction indicator lamp (MIL) to illuminate.
  1. The ECM/TCM turns OFF the MIL after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
  2. A current DTC clears when the malfunction is no longer present.
  3. A history DTC clears when the control module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated "current" or "active" status. Loss-of- communication U-codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios: A control module on the data communication circuit was disconnected while the communication circuit is awake. Power to one or more control modules was interrupted during diagnosis. A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold. Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialize at the same time. If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.
  2. A control module may have a U-code stored in history that does not require any repairs. Issues with late or corrupted messages between control modules can be temporary with no apparent symptom or complaint; this does not mean the control module is faulty. Do not replace a control module based only on a history U-code.
  3. Do not replace a control module reporting a U-code. The U-code identifies which control module needs to be diagnosed for a communication issue.
  4. Communication may be available between the BCM and the scan tool with either the low or high speed GMLAN serial data system inoperative. This condition is due to the BCM using both the low and high speed GMLAN systems.
  5. Use «Data Link References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system__data-link-references) to determine if the control module uses high or low speed GMLAN serial data communications.
  6. Some control modules may not have internal protection for specific control circuits and may open a B+ or ignition fuse. If a fuse is open and the B+ or ignition circuit is not shorted to ground, ensure none of the control circuits are shorted to ground before replacing the control module.
  7. This diagnostic can be used for any control module that is not communicating, regardless of the type of serial data circuit it is connected to, providing the vehicle is equipped with the control module.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Verify that DTC U1814, U2099, B1428, B1370, B1380, B1440, or B1441 is not set.

  1. If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .

Note. Use the schematic to identify the following: Control modules the vehicle is equipped with Control module locations on the low and high speed GMLAN serial data circuits The control modules B+, ignition, ground, communication enable and serial data circuit terminals

  1. Determine the control module that is not communicating. Refer to «Control Module U Code List»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system__control-module-u-code-list) .
  2. Ignition OFF, disconnect the harness connector of the control module that is not communicating.
  3. Test for less than 10 ohms between each ground circuit terminal and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. If equipped, verify that a test lamp illuminates between each B+ circuit terminal and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
  5. If equipped, ignition ON, verify that a test lamp illuminates between each ignition circuit terminal and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
  6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup circuit terminal and ground. If the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
  7. Ignition OFF for 60 seconds, test for less than 5 ohms between the serial data circuit terminals and the appropriate DLC terminal listed below: Class 2 serial data circuit terminal 2 Low speed GMLAN serial data terminal 1 High speed GMLAN serial data terminal 6 or 14 If greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module and a control module setting the DTC or a serial data splice pack.
  8. If all circuits test normal, replace the control module that is not communicating.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
B+ - Window MotorU1511, U1512U1511, U1512
Serial Data - Driver Window Motor, Terminal 5U1500 02U1511U1500 01
Serial Data - Passenger Window Motor, Terminal 5U1500 02U1512U1500 01
Ground - Window MotorU1511 1 , U1512 1
Ignition - Electronic Compass ModuleU1511U1511
Serial Data - Electronic Compass Module, Terminal 3U1511U1511U1511
Ground - Electronic Compass ModuleU1511
1 Either or both DTC may set depending on the location of the open/high resistance.

The driver door module (DDM) and the front passenger door module (FPDM) communicate with window regulator motors on the local interconnect network bus 1 and the local interconnect network bus 2 circuits respectively. When the driver power window switch is activated to a desired position, the DDM examines the request and checks for messages from other vehicle control modules prohibiting window movement. If no prohibitive messages have been received, the DDM will send a LIN serial data message to the driver door window motor to move the window to the desired position.

When the DDM receives a request to operate one of the right side passenger windows from the driver master control, a GMLAN serial data message is sent to the PDM. The PDM examines the request and checks for messages from other vehicle control modules prohibiting the window movement. If no prohibitive messages have been received, the PDM will send a LIN serial data message to the appropriate window motor to move the window as requested.

The DDM and PDM supply their respective rear power window switches with a 12 V reference and signal circuit. The rear power window switches contain separate resistors for each switch position. When a rear power window switch is activated, the associated door control module interprets the signal and checks for messages from other vehicle control modules prohibiting the window movement. If no prohibitive messages have been received, the door control module sends a LIN serial data message to the appropriate power window motor commanding the requested window position.

The driver information center (DIC) displays the compass based on serial data message from the BCM. The compass module communicates with the body control module (BCM) through a bi-directional data circuit (LIN).

The system voltage is between 9-16 V.

U1500 01

When there is a short to voltage in the local interconnect network bus circuit.

U1500 02

When there is a short to ground in the local interconnect network bus circuit.

U1500 31

The module has detected an internal malfunction.

U1511, U1512

The DTC will set when there is an open/high resistance in the local interconnect network bus circuit, or an open in the voltage or ground circuits of the motor or module.

U1500

The individual LIN bus will be inoperative, disabling all windows on one side of the vehicle.

The module refuses all additional inputs.

U1511

  1. If set in the driver door lock window switch or passenger door lock window switch, no window on the specific side of the vehicle will operate if the open is before the first splice from the door module, and both DTC U1511 and U1512 should set. If open after the first splice, the individual window will be inoperative and a single DTC should set.
  2. If set in the BCM, the compass is inoperative in the DIC.

U1512

No window on the specific side of the vehicle will operate if the open is before the first splice from the door module, and both DTC U1511 and U1512 should set. If open after the first splice, the individual window will be inoperative and a single DTC should set.

  1. The current DTC will clear when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
  1. A window regulator motor may cause a short to the local interconnect network bus circuit, and will cause all windows on one side to be inoperative.
  2. An open/high resistance between the door module and the first splice from the module will cause all windows on one side to be inoperative.
  3. An open/high resistance between the window regulator motor and the first splice from the motor will cause only one window to be inoperative.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Instrument Cluster Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Verify that DTC U1500 31 is not set, If the DTC is set, replace the appropriate window motor.
  2. Verify that DTC U1511 is not set in the BCM. If DTC U1511 is set in the BCM, perform the Compass Malfunction Test.
  3. Perform the Window Malfunction Test.

Compass Malfunction Test

  1. Ignition OFF, disconnect the harness connector at the electronic compass module.
  2. Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 1 and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  4. Test for 6.0-7.0 V between the LIN Bus circuit terminal 3 and ground. If greater than the specified range, test the LIN Bus circuit for a short to voltage. If the circuit tests normal, replace the BCM. If less than the specified range, test the LIN Bus circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, replace the electronic compass module.

Window Malfunction Test

  1. Ignition OFF, disconnect the harness connector at the appropriate window motor.
  2. Ignition OFF, test for less than 2.0 ohms between the ground circuit terminal 4 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 3 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  4. Test for 6.0-7.0 V between the LIN circuit terminal 5 and ground. If greater than the specified range, test the LIN circuit for a short to voltage. If the circuit tests normal, replace the door module. If less than the specified range, test the LIN circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the door module.
  5. If all circuits test normal, replace the window motor.

Note. Each window regulator motor or front window and door lock switch, if replaced needs to be setup for proper operation.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Front Side Door Window Regulator Motor Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/heated-glassdefoggers/#fixed-and-moveable-windows-system)
  2. «Rear Side Door Window Regulator Motor Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/heated-glassdefoggers/#fixed-and-moveable-windows-system)
  3. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for window, and door lock switches (door modules), window regulator motors, or electronic compass module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The PTLAN serial data circuits are serial data buses used to communicate information between the control modules. The PTLAN serial data circuits also connect directly to the data link connector (DLC) for programming purposes. If this serial data system is inoperative the modules will still communicate with the scan tool due to other serial data systems but not with each other. Communication with the scan tool for the modules on the PTLAN bus is through the serial data gateway module (SDGM) on the HSGMLAN serial data system.

  1. Supply voltage to the modules are in the normal operating range.
  2. The ignition switch in any position other than START.

The module setting the DTC has attempted to establish communications on the PTLAN serial data circuits more than 3 times.

  1. The module suspends all message transmission.
  2. The MIL and battery indicators will illuminate, along with several DIC messages.
  3. The vehicle may continue to run for several minutes, then will stall and not start.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Verify that U0074 is not set.

  1. If the DTC is set, refer to «DTC U0074»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
SDG Module B+ VoltageU1812, U1821, U1862, U1875, U1878, U1888, U0129U1812, U1821, U1862
Wake Up SignalU1812, *B137A 06U1812U1813, *B137A 01
SDG Module GroundU1812, U1821, U1862
* Sets in the SDG module. No crank, no start. Battery pack contactors are open. drive motor generator battery control module and SDG module will both be inoperative

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data gateway (SDG) module translates serial data messages between the high speed GMLAN serial data bus, the low speed GMLAN serial data bus, and the high speed hybrid GMLAN serial data bus. Messages between the drive motor generator battery control module and the other hybrid system control modules must pass thru the SDG module. The wake up circuit sends a voltage from the SDG module to the drive motor generator battery control module to initiate certain module functions. DTC U1812 is set by the drive motor generator battery control module, but is stored in and reported by the hybrid powertrain control module (HPCM).

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur.

The drive motor generator battery control module did not receive voltage from the SDG module on the wake up signal circuit.

  1. The driver information center (DIC) displays the message Service Hybrid System.
  2. Multiple DTCs may set depending on the fault location and when the fault occurred.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

A false DTC U1812 can set if the engine does not crank while the ignition key is held in the start position for greater than 3 seconds. Diagnose the engine does not crank condition first.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Hybrid Controls Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#hybrid-engine-controls-wiring-schematics)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
  1. Verify that DTC U1862 is not set in the HPCM. If the DTC is set, refer to «DTC U1862»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .
  2. Verify that DTC B137A is not set in the SDG module. If the DTC is set, refer to «DTC B137A»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .
  1. Ignition OFF, disconnect the inline harness connector X350 at the drive motor generator battery.
  2. Ignition ON, verify that a test lamp illuminates between the wake up signal circuit terminal 10 X350 and ground. If the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuit tests normal, replace the SDG module. If the test lamp illuminates, test the wake up signal circuit of the drive motor generator battery control module electrical harness for an open/high resistance.
  3. If all circuits test normal, replace the drive motor generator battery control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Wake Up SignalU1812, *B137A 06U1812U1813, *B137A 01
* Sets in the SDG module. No crank, no start. Battery pack contactors are open. drive motor generator battery control module and SDG module will both be inoperative

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data gateway (SDG) module translates serial data messages between the high speed GMLAN serial data bus, the low speed GMLAN serial data bus, and the high speed hybrid GMLAN serial data bus. Messages between the drive motor generator battery control module and the other hybrid system control modules must pass thru the SDG module. The wake up circuit sends a voltage from the SDG module to the drive motor generator battery control module to initiate certain module functions. DTC U1813 is set by the drive motor generator battery control module, but is stored in and reported by the hybrid powertrain control module (HPCM).

  1. The system voltage is between 9-18 volts.
  2. Ignition is OFF.

The drive motor generator battery control module receives voltage on wake up signal circuit for greater than 3 seconds when the ignition is OFF.

The hybrid system signals the engine control module (ECM) to request illumination of the malfunction indicator lamp (MIL).

  1. A current DTC clears when the malfunction is no longer present, including a key ON condition when both wake up signals are energized.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

DTC U1813 will always set with SDG module DTC B137A 01.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Hybrid Controls Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#hybrid-engine-controls-wiring-schematics)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Verify that DTC B137A is not set in the SDG module.

  1. If the DTC is set, refer to «DTC B137A»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Accessory Wake Up Serial DataU1814U0100-U0299

The accessory wake up serial data circuit is a positive voltage signal to wake up multiple control modules. The signal is activated in 2 ways; any time the ignition switch is in the ACC or RUN position, or anytime the body control module (BCM) determines that communication is needed from the powertrain. When the ignition switch is in the ACC or RUN position, the accessory voltage circuit input to the BCM is internally connected to the accessory wake up serial data circuit output, and voltage is supplied to the modules. The BCM also supplies voltage to the accessory wake up serial data circuit when it determines that communication is necessary with the powertrain and the ignition is not in the ACC or RUN position such as during remote start.

Modules activated by the accessory wakeup serial data circuit are as follows

  1. Engine control module (ECM)
  2. Transmission control module (TCM)
  3. Transfer case control module (TCCM) (RPO NP8)
  4. Serial data gateway module (SDGM) (RPO HP2)
  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur.

The BCM senses a short to ground on the accessory wake up serial data circuit.

  1. The modules use a default value for the missing parameters until the next ignition cycle.
  2. The module(s) is never signaled, therefore the specific subsystem(s) will not function.
  3. The vehicle may not start.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Short to ground may also set multiple no communication codes for GMLAN high speed modules.

Schematic Reference

  1. DLIS Fuse and Ignition Switch in «Power Distribution Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#wiring-systems-and-power-management-schematic-and-wiring-harness-routing-diagrams)
  2. «Body Control System Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  3. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
  1. With the ignition OFF, disconnect the module harness connectors listed below one at a time. After each disconnect, retest for current DTCs. DTC U1814 should remain current. Engine control module (ECM) - X1 Transmission control module (TCM) - X1 Transfer case control module (TCCM) (RPO NP8) - X2 Serial data gateway module (SDGM) (RPO HP2) - X2 If the DTC becomes history, replace the module disconnected before the DTC became history.
  2. Ignition OFF, disconnect the X4 harness connector at the BCM.
  3. Test for infinite resistance between the accessory wake up serial data circuit terminal 19 and ground. If less than the specified range, test the serial data circuit for a short to ground.
  4. If the circuit tests normal, replace the BCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
B+1U1815/U1816
B+1U1815/U1816
Ignition1U1815/U1816
Module Ground StrapU1815/U18161
High Speed hybrid GMLAN Serial Data (+)U0074U1815/U1816U0074
High Speed hybrid GMLAN Serial Data (-)U0074U1815/U1816U0074
Hybrid Module Wake-up SignalB137AU1815/U1816
1. Multiple symptoms may occur due to open fuses.

Modules connected to the high speed hybrid GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The communication enable and the wakeup circuits are energized by a specific module to activate another specific module when the ignition key is in ACC, ON or START. Only the modules using high speed GMLAN serial data are connected to the enable or wakeup circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wakeup circuits.

The motor control module (MCM) 1, 2, and the hybrid powertrain control module (HPCM) are all internal to the drive motor power inverter module (PIM). The MCMs communicate only with the HPCM with the HPCM sending out DTC information to other modules regarding the MCMs. All circuits to the MCM are also internal to the PIM and is replaced as a single component.

Communication diagnostics for the serial data, including module power and ground as well as the wakeup circuits for both MCMs, and the HPCM are all diagnosed from external sources only to the PIM connector because any circuit fault condition within the PIM will cause a complete replacement.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur from this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. DTC U1815 can set current in the HPCM, ECM, and the SDGM.
  2. If DTC U1815 is only set in the HPCM, the PIM must be replaced due to all circuits between the HPCM and MCM being internal to the PIM.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
  1. Verify that DTC B137A is not current in the serial data gateway module (SDGM). If the DTC is current in the SDGM, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  2. Verify that DTC U1815 is not set current only in the HPCM. If the DTC is current in the HPCM only, replace the drive motor power inverter module (PIM).
  1. Ignition OFF, disconnect the harness connector X1 at the PIM.
  2. Test for less than 5 ohms between the PIM case and ground. If greater than the specified range, test the ground strap for an open/high resistance. If the circuit tests normal, replace the PIM.
  3. Ignition ON, verify that a test lamp illuminates between the following voltage circuit terminals of the PIM and ground. Terminal 6 Terminal 7 Terminal 20 If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the signal circuit terminal 19 and ground. If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the SDGM.
  5. Ignition OFF, disconnect the harness connector X3 at the engine control module.
  6. Test for less than 1.0 ohm on the high speed hybrid GMLAN serial data circuits between the following ECM and PIM circuit terminals. ECM X 3 terminal 53 and PIM X 1 terminal 11 ECM X 3 terminal 33 and PIM X 1 terminal 10 If greater than the specified range, test the circuit for open/high resistance
  7. If all circuits test normal, replace the PIM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
B+1U1815/U1816
B+1U1815/U1816
Ignition1U1815/U1816
Module Ground StrapU1815/U18161
High Speed hybrid GMLAN Serial Data (+)U0074U1815/U1816U0074
High Speed hybrid GMLAN Serial Data (-)U0074U1815/U1816U0074
Hybrid Module Wake-up SignalB137AU1815/U1816
1. Multiple symptoms may occur due to open fuses.

Modules connected to the high speed hybrid GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The communication enable and the wakeup circuits are energized by a specific module to activate another specific module when the ignition key is in ACC, ON or START. Only the modules using high speed GMLAN serial data are connected to the enable or wakeup circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wakeup circuits.

The motor control module (MCM) 1, 2, and the hybrid powertrain control module (HPCM) are all internal to the drive motor power inverter module (PIM). The MCMs communicate only with the HPCM with the HPCM sending out DTC information to other modules regarding the MCMs. All circuits to the MCM are also internal to the PIM and is replaced as a single component.

Communication diagnostics for the serial data, including module power and ground as well as the wakeup circuits for both MCMs, and the HPCM are all diagnosed from external sources only to the PIM connector because any circuit fault condition within the PIM will cause a complete replacement.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur from this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure does not allow removal of the SDGM, only access to the connector. Refer to «Instrument Panel Center Trim Panel Replacement (Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) or «Instrument Panel Center Trim Panel Replacement (Except Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
  2. DTC U1816 can set current in the HPCM, ECM, and the SDGM.
  3. If DTC U1816 is only set in the HPCM, the PIM must be replaced due to all circuits between the HPCM and MCM being internal to the PIM.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
  1. Verify that DTC B137A is not current in the serial data gateway module (SDGM). If the DTC is current in the SDGM, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  2. Verify that DTC U1816 is not set current only in the HPCM. If the DTC is current in the HPCM only, replace the drive motor power inverter module (PIM).
  1. Ignition OFF, disconnect the harness connector X1 at the PIM.
  2. Test for less than 5 ohms between the PIM case and ground. If greater than the specified range, test the ground strap for an open/high resistance. If the circuit tests normal, replace the PIM.
  3. Ignition ON, verify that a test lamp illuminates between the following voltage circuit terminals of the PIM and ground. Terminal 6 Terminal 7 Terminal 20 If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the signal circuit terminal 19 and ground. If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the SDGM.
  5. Ignition OFF, disconnect the harness connector X3 at the engine control module.
  6. Test for less than 1.0 ohm on the high speed hybrid GMLAN serial data circuits between the following ECM and PIM circuit terminals. ECM X 3 terminal 53 and PIM X 1 terminal 11 ECM X 3 terminal 33 and PIM X 1 terminal 10 If greater than the specified range, test the circuit for open/high resistance
  7. If all circuits test normal, replace the PIM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
PTLAN + (circuit 6105)U0074*U1817* **, U189A in HPCM, U182A in SDGMU0074*
PTLAN - (circuit 6106)U0074*U1817* **, U189A in HPCM, U182A in SDGMU0074*
* Other modules/DTCs will set with this fault. ** This DTC may set in the ECM or the SDGM.

Modules connected to the PTLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur for this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

With a scan tool, ensure the following DTCs are not present in the modules as follows

HPCM

U189A

SDGM

  1. U182A
  2. U0074
  1. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC.
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
ECM B+1*1*
ECM Ground1*
PTLAN +U0074*U1818*, U189AU0074*
PTLANU0074*U1818*, U189AU0074*
* Other modules/DTCs will set with this fault. 1. Multiple DTCs including U1818 may set, and multiple symptoms including no start may occur

Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

DTC U1818 will set in the serial data gateway module (SDGM) when no communication is established with the ECM on the PTLAN serial data bus.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur from this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure does not allow removal of the SDGM, only access to the connector. Refer to «Instrument Panel Center Trim Panel Replacement (Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) or «Instrument Panel Center Trim Panel Replacement (Except Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
  2. If the ECM is inoperative due to an open in the voltage or ground circuits then DTC U0100 will be set current in the power steering control module (PSCM).
  3. Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions when the fault occurs.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Verify the following DTCs are not set in the modules as follows

  1. PSCM - U0100
  2. SDGM - U189A
  1. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  1. Ignition OFF, disconnect harness connector X1 of the APM and the EBCM.
  2. Test for less than 1.0 ohm between the APM and the EBCM on the following circuit terminals. PTLAN + APM terminal 5 and EBCM terminal 33 PTLAN - APM terminal 1 and EBCM terminal 21 If greater than the specified range, test the circuit for an open/high resistance.
  3. Ignition OFF, disconnect harness connector X1 of the SDGM.
  4. Test for less than 1.0 ohm between the EBCM and the SDGM on the following circuit terminals. PTLAN + EBCM terminal 34 and SDGM terminal 13 PTLAN - EBCM terminal 22 and SDGM terminal 11 If greater than the specified range, test the circuit for an open/high resistance.
  5. If the circuits test normal, replace the SDGM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Ignition Voltage (circuit 948)U1820*, U189A in HPCM, U1818 in SDGMU1820*, U189A in HPCM, U1818 in SDGM
Ground (circuit 950)U1820*, U189A in HPCM, U1818 in SDGM
PTLAN + (circuit 6105)U0074*U1820*, U189A in HPCM, U1818 in SDGMU0074*
PTLAN - (circuit 6106)U0074*U1820*, U189A in HPCM, U1818 in SDGMU0074*
* Other modules/DTCs will set with this fault.

Modules connected to the PTLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur for this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
  1. Verify the following DTCs are not set in the modules as follows: SDGM - U1818 HPCM - U189A If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  2. Ignition OFF, disconnect the harness connector of the yaw rate and lateral acceleration sensor.
  3. Verify that a test lamp illuminates between the ground circuit terminal 6 and B+. If the test lamp does not illuminate, test the circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the EBCM.
  4. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal 1 and ground. If the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.
  5. Ignition OFF, disconnect harness connector X1 of the SDGM.
  6. Test for less than 1.0 ohm between the SDGM and the yaw rate and lateral acceleration sensor on the following circuit terminals. PTLAN + SDGM terminal 14 and yaw rate and lateral acceleration sensor terminal 2 PTLAN - SDGM terminal 12 and yaw rate and lateral acceleration sensor terminal 3 If greater than the specified range, test the circuit for an open/high resistance.
  7. If the circuits test normal, replace the SDGM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
B+U1821*U1821
GroundU1821*
PTLAN +U0074*U1821, 1U0074*
PTLANU0074*U1821, 1U0074*
* Other modules/DTCs may set with this fault. 1. Multiple DTCs including U1821 may set and multiple symptoms including a no start condition may occur.

Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

DTC U1821 will set in the drive motor generator power inverter module when no communication is established with the accessory DC power control module on the PTLAN serial data bus.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur from this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions when the fault occurs.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Special Tools

EL-48900 HEV Safety Kit

Verify DTC U182A is not set in the serial data gateway module (SDGM).

  1. If the DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  1. Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to «High Voltage Disabling»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system__high-voltage-disabling) .
  2. Ignition OFF, disconnect harness connector X4 of the accessory DC power control module.
  3. Test for less than 1.0 ohm between the accessory DC power control module connector terminal and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  4. Ignition ON, disconnect harness connector X3 of the accessory DC power control module.
  5. Verify that a test lamp illuminates between the accessory DC power control module connector terminal A and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  6. Ignition OFF, disconnect harness connector X1 of the accessory DC power control module and the drive motor generator power inverter module.
  7. Test for less than 1.0 ohm at the accessory DC power control module connector and drive motor generator power inverter module connector between the following connector serial data terminals. Accessory DC power control module terminal 1 and drive motor generator power inverter module terminal 24 Accessory DC power control module terminal 2 and drive motor generator power inverter module terminal 25 If greater than the specified value, test the serial data circuits for an open/high resistance.
  8. Test for infinte resistance between the accessory DC power control module terminal 2 and accessory DC power control module terminal 1. If less than the specified value, test the serial data circuits for a short between the circuits.
  9. If all circuits test normal, replace the accessory DC power control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Yaw and Lateral Accelerometer Sensor 12 V Reference11
Yaw and Lateral Accelerometer Sensor CAN Bus High Serial DataU1826 71, U1826 72, U1826 7FU1826 7F
Yaw and Lateral Accelerometer Sensor CAN Bus Low Serial DataU1826 71, U1826 72, U1826 7FU1826 7F
Yaw and Lateral Accelerometer Sensor Ground1
1. Circuit Inoperative

The electronic brake control module (EBCM) activates the other control modules connected to the CAN serial data circuits by applying voltage when the ignition key is in ACC, ON or START. The EBCM and Yaw and Lateral Accelerometer Sensor are connected to the CAN bus serial data circuits. For more information on CAN bus serial data refer to Data Link Communications Description and Operation .

  1. The system voltage is between 9-16 V.
  2. The vehicle power mode master requires serial data communication to occur.

A supervised periodic message that includes the transmitter module availability has not been received.

  1. The vehicle stability enhancement system (VSES), if equipped, and traction control system (TCS) will not function.
  2. System OFF lamps will illuminate for these systems.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. Use the DTC Descriptor list above to determine the module which is not communicating.
  2. If there are multiple non-communicating modules choose the one closest to the EBCM.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Antilock Brake System Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-non-hybrid-greater-thanequal-to-3900-kg-8600-lb-gvw-with-tcs-ves)
  3. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition OFF, disconnect the harness connector at the Yaw and Lateral Accelerometer Sensor.
  2. Test for less than 5 ohms between the Yaw and Lateral Accelerometer Sensor ground circuit terminal 6 and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the Yaw and Lateral Accelerometer Sensor voltage (12 V reference) circuit terminal 1 and ground. If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
  4. Ignition OFF, disconnect the harness connector at the EBCM
  5. Test for less than 1 ohms in each serial data circuit between the Yaw and Lateral Accelerometer Sensor and the EBCM. Yaw and Lateral Accelerometer Sensor serial data circuit terminal 2 and EBCM serial data circuit terminal 33 Yaw and Lateral Accelerometer Sensor serial data circuit terminal 3 and EBCM serial data circuit terminal 21 If greater than the specified value, test the Yaw and Lateral Accelerometer Sensor serial data circuits terminals 2 and 3 for an open/high resistance.
  6. If all circuits test normal, replace the Yaw and Lateral Accelerometer Sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-non-hybrid-less-than-3900-kg-8600-lb-gvw-with-ebd-vses)
  3. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
APM B+U182A*U182A*
APM Wake Up SignalU182A, B137B*U182A*U189A*
APM Powertrain Serial Data (+)U0074*U0074*U0074*
APM Powertrain Serial Data (+)U0074*U0074*U0074*
PIM B+U1829*U1829*
PIM IgnitionP2534*P2534*U209A*, B1453
PIM Wake Up SignalB137A*U1829*U189A*
PIM Powertrain Serial Data (+)U0074*U0074*U0074*
PIM Powertrain Serial Data (-)U0074*U0074*U0074*
* Other modules/DTCs will set with this fault.

Control modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the control modules. The control modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data gateway module (SDGM) energizes the wake up signal to activate the accessory DC power control module (APM) and another wake up signal to activate the hybrid powertrain control module (HPCM) which is inside the drive motor generator power inverter module (PIM) when communication is needed. The HPCM reports all DTCs for the APM.

  1. The system voltage is between 9-16 V.
  2. The ignition in RUN.

The powertrain serial data circuits between the SDGM and the APM or the PIM are open.

The control modules is never signaled, therefore the specific subsystems may not function. Depending on the fault, the MIL, battery indicator may illuminate and several DIC messages may be present.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. Circuits to the HPCM are diagnosed only to the PIM connector because the HPCM is replaced as part of the PIM.
  2. Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions when the fault occurs.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Hybrid Controls Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#hybrid-engine-controls-wiring-schematics)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
  1. Verify that DTC B137A, B137B or U189A is not present in the SDGM. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  2. Verify the DTC U0074 is not set. If DTC U0074 is set as a current or history code, refer to «DTC U0074»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .

APM

  1. Ignition OFF, test for less than 1.0 ohms between the accessory DC power control module case and ground strap. If greater than the specified value, test the ground circuit for an open/high resistance.
  2. Disconnect harness connector X3 of the accessory DC power control module.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit fuse is open, test the control circuits of the accessory DC power control module for a short to ground.
  4. Ignition OFF, disconnect harness connector X1 of the accessory DC power control module.
  5. Ignition ON, verify that a test lamp illuminates between the wake up signal circuit terminal 3 and ground. If the test lamp does not illuminate, test the wake up signal circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the serial data gateway module.
  6. If all circuits test normal, replace the accessory DC power control module.

PIM

  1. Ignition OFF, disconnect harness connector X1 of the drive motor generator power inverter module (PIM).
  2. Ignition ON, verify that a test lamp illuminates between each B+ circuit and ground. If the test lamp does not illuminate, test each B+ circuit for an open/high resistance. If the circuit fuse is open, test the control circuits of the PIM for a short to ground.
  3. Verify that a test lamp illuminates between the ignition circuit terminal 20 and ground. If the test lamp does not illuminate, test the ignition circuit for an open/high resistance. If the circuit fuse is open, test the control circuits of the PIM for a short to ground.
  4. Verify that a test lamp illuminates between the wake up signal circuit terminal 19 and ground. If the test lamp does not illuminate, test the wake up signal circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the serial data gateway module.
  5. If all circuits test normal, replace the drive motor generator power inverter module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
B+U182A*U182A*
Wake Up SignalU182A, B137B*U182A*U189A*
Powertrain Serial Data (+)U0074*U0074, U182A*U0074*
Powertrain Serial Data (-)U0074*U0074, U182A*U0074*
* Other modules/DTCs will set with this fault.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data gateway module (SDGM) energizes the wake up signal to activate the accessory DC power control module (APM) when communication is needed. The SDGM monitors the signal circuit for faults.

  1. The system voltage is between 9-16 V.
  2. The ignition in RUN.
  1. The APM wake up signal is open.
  2. The APM does not receive battery voltage.
  3. The powertrain serial data circuits between the SDGM and the APM are open.

The modules is never signaled, therefore the specific subsystems may not function. Depending on the fault, the MIL, battery indicator may illuminate and several DIC messages may be present.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure does not allow removal of the SDGM, only access to the connector. Refer to «Instrument Panel Center Trim Panel Replacement (Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) or «Instrument Panel Center Trim Panel Replacement (Except Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
  2. Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions when the fault occurs.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
  1. Verify that DTC B137B or U189A are not present in the SDGM. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  2. Verify the DTC U0074 is not set. If DTC U0074 is set as a current or history code, refer to «DTC U0074»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .
  1. Ignition OFF, test for less than 1.0 ohms between the accessory DC power control module case and ground strap. If greater than the specified value, test the ground circuit for an open/high resistance.
  2. Disconnect harness connector X3 of the accessory DC power control module.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit fuse is open, test the control circuits of the accessory DC power control module for a short to ground.
  4. Ignition OFF, disconnect harness connector X1 of the accessory DC power control module.
  5. Ignition ON, verify that a test lamp illuminates between the wake up signal circuit terminal 3 and ground. If the test lamp does not illuminate, test the wake up signal circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the serial data gateway module.
  6. If all circuits test normal, replace the accessory DC power control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master indicates that the need for serial data communications.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Verify that U0100 is not set.

  1. If the DTC is set, refer to «DTC U0100-U02FF (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «DTC U0100-U02FF (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master indicates that the need for serial data communications.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Verify that U0100 is not set.

  1. If the DTC is set, refer to «DTC U0100-U02FF (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «DTC U0100-U02FF (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
SDG Module B+ Voltage*U1862, U1888, U1878, U1875, U1821, U1812, U0129U1862, U1821, U1812
SDG Module Serial Data Communication EnableU1862U1862
High Speed GMLAN Serial Data Bus*U1862, U1888, U1886, U1885, U1879, U1878, U1876, U1875, U1866, U0140, U0129, U0102, U0101, U0100*U1888, U1878, U8175, U0129*U1862, U1888, U1886, U1885, U1879, U1878, U1876, U1875, U1866, U0140, U0129, U0102, U0101, U0100
High Speed GMLAN Serial Data Bus*U1862, U1888, U1886, U1885, U1879, U1878, U1876, U1875, U1866, U0140, U0129, U0102, U0101, U0100*U1888, U1878, U8175, U0129*U1862, U1888, U1886, U1885, U1879, U1878, U1876, U1875, U1866, U0140, U0129, U0102, U0101, U0100
SDG Module GroundU1862, U1821, U1812
Drive Motor Generator Battery Control Module B+ Voltage*U1862, U1888, U1878, U1875, U1821, U1812, U0129**U1888, U1878, U1875, U0129
* No crank, no start. Battery pack contactors are open. drive motor generator battery control module and SDG module will both be inoperative. ** No crank, no start. Battery pack contactors are open. drive motor generator battery control module is inoperative.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The enable signal circuit is energized by the body control module (BCM) to activate multiple modules when the BCM determines that communication is required. Some modules may still become active due to their own ignition voltage source if the enable circuit is not functional. The serial data gateway (SDG) module translates serial data messages between the high speed GMLAN serial data bus, the low speed GMLAN serial data bus, and the high speed hybrid GMLAN serial data bus. Messages between the drive motor generator battery control module and the other hybrid system control modules must pass thru the SDG module. DTC U1862 is set by the drive motor generator battery control module, but is stored in and reported by the hybrid powertrain control module (HPCM).

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur from the drive motor generator battery control module via the SDG module.

A supervised periodic message that includes the SDG module availability has not been received by the drive motor generator battery control module.

  1. The charging system will not operate properly and the vehicle battery will discharge as the vehicle is driven.
  2. The driver information center (DIC) displays the message Service Hybrid System.
  3. Multiple DTCs may set depending on the fault location and when the fault occurred.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. If the SDG module becomes inoperative, the drive motor generator battery control module will set DTC U1862 and other modules will set loss of communication DTCs against the SDG module.
  2. If serial data is lost between the SDG module and the drive motor generator battery control module multiple modules will set loss of communication DTCs against the drive motor generator battery control module.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Hybrid Energy Storage Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition OFF, disconnect the harness connector X2 at the SDG module.
  2. Ignition OFF and the scan tool disconnected, open and close the driver door, and wait 1 minute.
  3. Test for less than 5.0 ohms between the ground circuit terminal 18 X2 and ground. If greater than the specified range, test the circuit for an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 8 X2 and ground. If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance.
  5. Test for 10.5-12.5 volts between the serial data communication enable circuit terminal 16 X2 and ground. If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the applicable communication/control module.
  6. Ignition OFF, connect the harness connector X2 to the SDG module.
  7. Ignition OFF, disconnect the harness connector X1 at the SDG module.
  8. Ignition ON, test for 2.1-2.5 volts between the high speed GMLAN serial data bus low circuit terminal listed below and ground: Terminal 15 X1 Terminal 16 X1 If greater than the specified range, test the circuit for a short to voltage. If the circuit tests normal, replace the applicable communication/control module. If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the applicable communication/control module.
  9. If all circuits test normal, replace the SDG module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
BCM B+U1866*, U0140 in EBCMU1866*, U0140 in EBCM
BCM GroundU1866*, U0140 in EBCM
HSGMLAN + (circuit 2500)1*U1866*, U0140 in EBCM1*
HSGMLAN - (circuit 2501)1*U1866*, U0140 in EBCM1*
* Other modules/DTCs will set with this fault. 1. Scan tool does not communicate with high speed GMLAN device.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur fro this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Verify that DTC U0140 is not set in the electronic brake control module (EBCM).

  1. If DTC U0140 is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master indicates that the need for serial data communications.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Verify that U0102 is not set.

  1. If the DTC is set, refer to «DTC U0100-U02FF (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «DTC U0100-U02FF (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master indicates that the need for serial data communications.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Verify that U0101 is not set.

  1. If the DTC is set, refer to «DTC U0100-U02FF (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «DTC U0100-U02FF (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
BECM B+ (circuit 4240)U0146* in PSCMU1875* in HPCM, U0111 in SDGM
BECM Ground (circuit 2751)U1875* in HPCM, U0111 in SDGM
BECM Communication Enable Signal (circuit 5986)U1875* in HPCM, U2099 in BCMU1875* in HPCM, U0111 in SDGM
HSGMLAN + (circuit 2500)1*U1875* in HPCM, U0111 in SDGM1*
HSGMLAN - (circuit 2501)1*U1875* in HPCM, U0111 in SDGM1*
HPCM Ignition (circuit 2139)P2534P2534U1875* in HPCM, B1453 in SDGM
* Other modules/DTCs will set with this fault. 1. Scan tool does not communicate with high speed GMLAN device.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data communication enable and the accessory wake up serial data circuits are energized by a specific module to activate another specific module when the ignition key is in ACC, ON or START. Only the modules using high speed GMLAN serial data are connected to the enable or wake up circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wake up circuits.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur fro this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

With a scan tool, ensure the following DTCs are not present in the modules as follows

BCM

U2099

PSCM

U0146

SDGM

  1. SDGM - U0111
  2. SDGM - B1453
  1. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
ECM B+U1876*, U0100 in HPCMU1876*, U0100 in HPCM
ECM GroundU1876*, U0100 in HPCM
ECM Wake Up Signal (circuit 5985)U1876* in HPCM, U1814 in BCMU1876*, U0100 in HPCM
HSGMLAN + (circuit 2500)1*U1876*, U0100 in HPCM1*
HSGMLAN - (circuit 2501)1*U1876*, U0100 in HPCM1*
* Other modules/DTCs will set with this fault. 1. Scan tool does not communicate with high speed GMLAN device.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data communication enable and the accessory wake up serial data circuits are energized by a specific module to activate another specific module when the ignition key is in ACC, ON or START. Only the modules using high speed GMLAN serial data are connected to the enable or wake up circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wake up circuits.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur fro this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

With a scan tool, ensure the following DTCs are not present in the modules as follows

BCM

U1814

SDGM

U0100

  1. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
BECM B+ (circuit 4240)U0146* in PSCMU1878* in HPCM, U0111 in SDGM
BECM Ground (circuit 2751)U1878* in HPCM, U0111 in SDGM
BECM Communication Enable Signal (circuit 5986)U1878* in HPCM, U2099 in BCMU1878* in HPCM, U0111 in SDGM
HSGMLAN + (circuit 2500)1*U1878* in HPCM, U0111 in SDGM1*
HSGMLAN - (circuit 2501)1*U1878* in HPCM, U0111 in SDGM1*
HPCM Ignition (circuit 2139)P2534P2534U1875* in HPCM, B1453 in SDGM
* Other modules/DTCs will set with this fault. 1. Scan tool does not communicate with high speed GMLAN device.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data communication enable and the accessory wake up serial data circuits are energized by a specific module to activate another specific module when the ignition key is in ACC, ON or START. Only the modules using high speed GMLAN serial data are connected to the enable or wake up circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wake up circuits.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur fro this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

With a scan tool, ensure the following DTCs are not present in the modules as follows

BCM

U2099

PSCM

U0146

SDGM

  1. SDGM - U0111
  2. SDGM - B1453
  1. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
ECM B+U1879*, U0100 in HPCMU1879*, U0100 in HPCM
ECM GroundU1879*, U0100 in HPCM
ECM Wake Up Signal (circuit 5985)U1879* in HPCM, U1814 in BCMU1879*, U0100 in HPCM
HSGMLAN + (circuit 2500)1*U1879*, U0100 in HPCM1*
HSGMLAN - (circuit 2501)1*U1879*, U0100 in HPCM1*
* Other modules/DTCs will set with this fault. 1. Scan tool does not communicate with high speed GMLAN device.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data communication enable and the accessory wake up serial data circuits are energized by a specific module to activate another specific module when the ignition key is in ACC, ON or START. Only the modules using high speed GMLAN serial data are connected to the enable or wake up circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wake up circuits.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur fro this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

With a scan tool, ensure the following DTCs are not present in the modules as follows

BCM

U1814

SDGM

U0100

  1. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
HSGMLAN + (circuit 2500)U0073*U1885*U0073*
HSGMLAN - (circuit 2501)U0073*U1885*U0073*
* Other modules/DTCs will set with this fault.

Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

DTC U1885 will set in the hybrid powertrain control module (HPCM) when the drive motor generator battery control module (BECM) looses communication with the serial data gateway module (SDGM) on the HSGMLAN serial data bus. The BECM communicates only on the PTLAN serial data bus while the HPCM communicates on the PTLAN and the HSGMLAN serial data bus.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur from this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions when the fault occurs.

Verify the following DTCs are not set in the modules as follows

  1. Verify DTC U0111 is not set in the SDGM. If the DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  2. Verify DTC U1888 is not set in the HPCM. If the DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
ECM B+U1886*, U0100 in HPCMU1886*, U0100 in HPCM
ECM GroundU1886*, U0100 in HPCM
ECM Wake Up Signal (circuit 5985)U1886* in HPCM, U1814 in BCMU1886*, U0100 in HPCM
HSGMLAN + (circuit 2500)1*U1886*, U0100 in HPCM1*
HSGMLAN - (circuit 2501)1*U1886*, U0100 in HPCM1*
* Other modules/DTCs will set with this fault. 1. Scan tool does not communicate with high speed GMLAN device.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data communication enable and the accessory wake up serial data circuits are energized by a specific module to activate another specific module when the ignition key is in ACC, ON or START. Only the modules using high speed GMLAN serial data are connected to the enable or wake up circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wake up circuits.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur fro this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

The modules is never signaled, therefore the specific subsystems will not function.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

With a scan tool, ensure the following DTCs are not present in the modules as follows

BCM

U1814

SDGM

U0100

  1. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Drive Motor Generator Battery Control Module B+ VoltageU1888, U1878, U1875, U1862, U1821, U1812, U0129, *U0111U1888, U1878, U1875, *U0111
Drive Motor Generator Battery Control Module Serial Data Communication EnableU1888, U1878, U1875, *U209AU1888, U1878, U1875, *U0111
High Speed GMLAN Serial Data Bus +**U1888U1888, U1878, U1875, U0129, *U0111**U1888
High Speed GMLAN Serial Data Bus**U1888U1888, U1878, U1875, U0129, *U0121, *U0111**U1888
Drive Motor Generator Battery Control Module GroundU1888, U1878, U1875, *U0111
HPCM Ignition (circuit 2139)P2534P2534U1888, *B1453
* Sets in the SDG module ** No scan tool communication with hard fault. Additionl DTCs are set

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The serial data gateway (SDG) module translates serial data messages between the high speed GMLAN serial data bus, the low speed GMLAN serial data bus, and the high speed hybrid GMLAN serial data bus. Messages between the drive motor generator battery control module and the other hybrid system control modules must pass thru the SDG module. Only the modules using high speed GMLAN serial data are connected to the enable or wake up circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wake up circuits. DTC U1888 is set by the drive motor generator battery control module, but is stored in and reported by the hybrid powertrain control modul

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur fro this specific module.

A supervised periodic message that includes the transmitter module availability has not been received.

  1. The driver information center (DIC) displays the message Service Hybrid System.
  2. Multiple DTCs may set depending on the fault location and when the fault occurred.
  3. The vehicle will not start or run because the 300 volt battery contactors are OPEN.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

With a scan tool, ensure the following DTCs are not present in the modules as follows

BCM

U2099

PSCM

U0146

SDG module

  1. SDG module - U0111
  2. SDG module - B1453
  1. If the DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
PTLAN + 2 circuits at PIMU0074*U189A*U0074*
PTLAN - 2 circuits at PIMU0074*U189A*U0074*
Wake Up Signal circuit 968B137A* in SDGMU189A* **1
Wake Up Signal circuit 932B137B*U182A*U189A*
Wake Up Signal Circuit 5985U1814* in BCMU1812* in HPCMU209A* in SDGM
* Other modules/DTCs will set with this fault. ** Open at SDGM or BECM will set DTC U1812 in HPCM. Open at PIM will set DTC U189A in the HPCM. 1. Parasitic drain on battery, and may set DTC U1875, U1876, U1878, U1879 as history in the HPCM with the key ON, or as current with the key OFF.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The SDGM energizes the wake up signal to activate the accessory DC power control module (APM) and another wake up signal to activate the hybrid powertrain control module (HPCM) which is inside the drive motor power inverter module (PIM). The HPCM reports all DTC for the APM, therefore DTC U189A cannot be reported with the HPCM is inoperative.

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur.
  1. The HPCM does not receive voltage from the SDGM on the wake up signal circuit.
  2. The wake up circuit between the SDGM and the APM is shorted to voltage.
  3. Any of the 4 PTLAN circuits connected to the HPCM are open.

The modules is never signaled, therefore the specific subsystems may not function. Depending on the fault, the MIL, battery indicator may illuminate and several DIC messages be present.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure does not allow removal of the SDGM, only access to the connector. Refer to «Instrument Panel Center Trim Panel Replacement (Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) or «Instrument Panel Center Trim Panel Replacement (Except Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
  2. Circuits to the HPCM are diagnosed only to the PIM connector because the HPCM is replaced as part of the PIM.
  3. Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions when the fault occurs.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

With a scan tool, ensure the following DTCs are not present in the modules as follows

  1. BCM - U1814
  2. HPCM - U1812
  3. SDGM - B137A or U209A
  1. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  1. Ignition OFF, disconnect harness connector X1 of the APM.
  2. Test for less than 0.5 volts between the wake up signal circuit terminal 3 and ground. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the SDGM.
  3. Disconnect harness connector X1 of the PIM.
  4. Test for B+ between the wake up signal circuit terminal 19 and ground. If less than the specified value, test the circuit for an open/high resistance. If the circuit tests normal, replace the SDGM.
  5. Test for less than 1.0 ohm between the APM and the PIM on the following circuit terminals. PTLAN + APM terminal 2 and PIM terminal 25 PTLAN - APM terminal 1 and PIM terminal 24 If greater than the specified range, test the circuit for an open/high resistance.
  6. Ignition OFF, disconnect harness connector X3 of the engine control module (ECM).
  7. Test for less than 1.0 ohm between the APM and the ECM on the following circuit terminals. PTLAN + APM terminal 11 and ECM terminal 53 PTLAN - APM terminal 10 and ECM terminal 33 If greater than the specified range, test the circuit for an open/high resistance.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using the diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
High Speed GMLAN Serial Data Wake UpU2099, U0100-U0299 *U0100-U0299U0100-U0299 **
* Vehicle will not start. ** History only. If cleared the DTC will return after several ignition cycles.

The body control module (BCM) applies voltage to the high speed GMLAN serial data wake up circuit, when the ignition key is in ACC, ON or START to enable several modules for bus communication.

Depending on option content, modules that may receive the signal are as follows

  1. Drive motor generator battery control module (BECM) (RPO HP2)
  2. Electronic brake control module (EBCM)
  3. Electronic suspension control (ESC) module
  4. Fuel pump flow control module (FPCM)
  5. Power steering control module (PSCM) (RPO HP2)
  1. The system voltage is between 9-16 volts.
  2. The BCM attempts to enable the modules connected to the high speed GMLAN serial data wake up circuit.

The BCM senses a short to ground on the high speed GMLAN serial data wake up circuit.

  1. The output command is turned off while the malfunction is present.
  2. The modules use a default value for the missing parameters.
  3. The module(s) is never signaled, therefore the specific subsystem(s) will not function.
  4. The vehicle will not start while the circuit is shorted to ground.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Short to ground will also set multiple history no communication codes for GMLAN high speed modules

Schematic Reference

  1. «Body Control System Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information.

WARNINGAlways perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed. The High Voltage Disabling procedure will perform the following tasks: Identify how to disable high voltage. Identify how to test for the presence of high voltage. Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed. Failure to follow the procedures exactly as written may result in serious injury or death.
  1. With the ignition OFF, disconnect the module harness connectors listed below, if equipped, one at a time. After each disconnect, retest the BCM for current DTCs. DTC U2099 should remain current. Drive motor generator battery control module (BECM) (RPO HP2) - X 1 Electronic brake control module (EBCM) - X 1 Electronic suspension control (ESC) module - X 1 Fuel pump flow control module (FPCM) - X 1 Power steering control module (PSCM) (RPO HP2) - X 1 If the DTC becomes history, replace the module disconnected before the DTC became history.
  2. Perform the «High Voltage Disabling»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system__high-voltage-disabling) procedure.
  3. Ignition OFF, disconnect harness connector X1 of the BECM.
  4. Reconnect the 12-volt battery.
  5. Test the BCM for current DTCs. DTC U2099 should remain current. If the DTC becomes history, replace the BECM.
  6. Ignition OFF, disconnect the harness connector X 3 at the BCM.
  7. With the above harness connectors still disconnected, test for infinite resistance between the high speed GMLAN serial data wake up circuit terminal 19 and ground. If less than the specified value, test the wake up circuit for a short to ground.
  8. If all circuits test normal and DTC is current, replace the BCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Ignition Voltage (Circuit 2139)P2534* **P2534**U209A** or B1453
Ignition Voltage (Circuit 239)B1453* **B1453**U209A** or B1453
Communication Enable Signal (Circuit 5986)U209A** or U2099U209A**
Wake Up Signal (Circuit 5985)U1814*U1812*U209A*
* Circuit fuse will open ** May set other module/DTCs.

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

Wake up signal circuits are energized by the body control module (BCM) to activate the serial data gateway module (SDGM) and other modules, including the BECM, immediately when serial data is required. Additionally after receiving this signal the SDGM energizes another wake up signal to activate the drive motor generator battery control module (BECM) among others.

  1. The system voltage is between 9-16 volts.
  2. The ignition key is OFF.
  1. The communication enable signal circuit is open/high resistance.
  2. The wake up signal circuit is shorted to voltage.

The MIL may illuminate and the DIC may display multiple messages.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure does not allow removal of the SDGM, only access to the connector. Refer to Instrument Panel Center Trim Panel Replacement (Cadillac) or Instrument Panel Center Trim Panel Replacement (Except Cadillac) .

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

With a scan tool, ensure the following DTCs are not present in the modules as follows

BCM

  1. U1814
  2. U2099

SDGM

  1. U1812
  2. B1453
  1. If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
  1. Ignition OFF, disconnect the harness connector X2 at the SDGM.
  2. Verify less than 0.5 volts between the wake up signal circuit terminal 19 and ground. If greater than the specified range, test the circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  3. Ignition ON, verify B+ between the communication enable signal circuit terminal 16 and ground. If less than the specified value, test the circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, replace the SDGM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Wake Up Signal (circuit 5986)U209A in SDGM or U2099 in BCMU209A*U209D**
* Other modules will set other DTC with this fault. ** Will set DTC U209D as current with the key OFF, and as history with the key ON. Will also likely cause a parasitic drain on battery.

Modules connected to the LAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

2 wake up signal circuits (5986, 5985) are energized by the body control module (BCM) to activate multiple modules including the drive motor generator battery control module (BECM) when serial data is required. Wake up signal circuit (968) is energized by the serial data gateway module (SDGM) to activate the BECM immediately after the BCM energizes circuit 5986 and 5985. The BECM compares the status of both wake up circuits.

  1. The system voltage is between 9-18 volts.
  2. Ignition key OFF.

The BECM receives voltage from the BCM on wake up signal circuit 5986 for 3 seconds with the ignition OFF.

The hybrid powertrain control module (HPCM) will set DTC U209D.

  1. A current DTC clears when the malfunction is no longer present, including a key ON condition when both wake up signals are energized.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. DTC U209D will only set as current with the ignition in the OFF position. It will become history when the ignition is turned ON.
  2. When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure does not allow removal of the SDGM, only access to the connector. Refer to «Instrument Panel Center Trim Panel Replacement (Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) or «Instrument Panel Center Trim Panel Replacement (Except Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
  3. Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions when the fault occurs.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)
WARNINGAlways perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed. The High Voltage Disabling procedure will perform the following tasks: Identify how to disable high voltage. Identify how to test for the presence of high voltage. Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed. Failure to follow the procedures exactly as written may result in serious injury or death.
  1. Perform the «High Voltage Disabling»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system__high-voltage-disabling) procedure.
  2. Ignition OFF, disconnect harness connector X1 of the BECM.
  3. Reconnect the 12-volt battery.
  4. Ignition OFF and scan tool disconnected, test for less than 1 volt between wake up signal terminal 13 and ground. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for module replacement, setup, and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit Description

The GMLAN serial data circuits are controller area network (CAN) serial data buses used to communicate information between the control modules. Typical data transmission speeds must be high enough to ensure that a required real-time response is maintained. On this vehicle there are 2 totally different types of GMLAN serial data circuits, the high speed 2-wire circuit and low speed single wire circuit. Refer to Data Link Communications Description and Operation for the complete description of these buses. The GMLAN serial data circuits also communicate directly to the DLC connector. Messages are interpreted by the externally connected CANdi module which acts as a transceiver for the scan tool.

Modules connected to the GMLAN serial data circuits monitor communications during normal vehicle operation, where operation information is exchanged among the modules. All the modules on the GMLAN networks, maintain a transmit error counter (TEC) and a receive error counter (REC). The counter values increase with detected errors and will decrease with error-free messages. If the TEC value exceeds 255, the controller removes itself from the network and DTC U2100 will result.

  1. Supply voltage to the modules are in the normal operating range.
  2. The vehicle is in the RUN power mode.

The module setting the DTC has attempted to establish communications on the GMLAN circuits for more than 7 times.

  1. The module suspends all message transmission.
  2. The module uses default values for all parameters received on the serial data circuits.
  3. The module inhibits the setting of all other communication DTCs.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. This DTC cannot be retrieved with a current status. Diagnosis of a current DTC is accomplished via the symptom, «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) , or «Scan Tool Does Not Communicate with Low Speed GMLAN Device»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) depending on the module serial data communication.
  2. An intermittent condition is likely to be caused by a short on the GMLAN serial data circuits. Use the «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) , or «Scan Tool Does Not Communicate with Low Speed GMLAN Device»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) procedure in order to isolate an intermittent condition.
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Modules connected to the GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have programmed information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are also supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module.

DTC U2103 will set when fewer modules are detected on the buss before the modules can learn the other module IDs. If the communication buss is opened, or if the module power supply is lost when the vehicle is in the OFF power mode, and then placed in the RUN power mode, U2103 will set in specific modules.

  1. Voltage supplied to the modules is in the normal operating voltage range.
  2. The vehicle power mode requires serial data communication to occur.
  3. The DTC U2100 does not have a current status.

A supervised periodic message that includes the transmitter module availability has not been received.

The module uses a default value for the missing parameter.

  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
  1. Diagnosis of this DTC is accomplished via the symptom, «DTC U0100-U02FF (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «DTC U0100-U02FF (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .
  2. An intermittent condition is likely to be caused by a short on the GMLAN serial data circuits. Use the «DTC U0100-U02FF (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «DTC U0100-U02FF (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) procedure in order to isolate an intermittent condition.
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Modules connected to the CAN bus serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

The electronic brake control module (EBCM) activates the other modules connected to the CAN serial data circuits by applying voltage when the ignition key is in ACC, ON or START. The EBCM, Yaw Rate and Lateral Acceleration Sensor are the only modules connected to the CAN bus serial data circuits. For more information on CAN bus serial data refer to Data Link Communications Description and Operation .

  1. The system voltage is between 9-16 volts.
  2. The vehicle power mode master requires serial data communication to occur.

A supervised periodic message that includes the transmitter module availability has not been received.

  1. The vehicle stability enhancement system (VSES), if equipped, and traction control system (TCS) will not function.
  2. System OFF lamps will illuminate for these systems.
  1. A current DTC clears when the malfunction is no longer present.
  2. A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
  1. Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated "current" or "active" status. Loss-of- communication U-codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios: A control module on the data communication circuit was disconnected while the communication circuit is awake. Power to one or more modules was interrupted during diagnosis. A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold. Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialize at the same time. If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.
  2. A control module may have a U-code stored in history that does not require any repairs. Issues with late or corrupted messages between control modules can be temporary with no apparent symptom or complaint; this does not mean the control module is faulty. Do not replace a control module based only on a history U-code.
  3. Do not replace a control module reporting a U-code. The U-code identifies which control module needs to be diagnosed for a communication issue.
  4. Communication may be available between the BCM and the scan tool with either the low or high speed GMLAN serial data system inoperative. This condition is due to the BCM using both the low and high speed GMLAN systems.
  5. Use to determine if the module uses high or low speed GMLAN serial data communications.
  6. Some control modules may not have internal protection for specific control circuits and may open a B+ or ignition fuse. If a fuse is open and the B+ or ignition circuit is not shorted to ground, ensure none of the control circuits are shorted to ground before replacing the control module.
  7. This diagnostic can be used for any control module that is not communicating, regardless of the type of serial data circuit it is connected to, providing the vehicle is equipped with the control module.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Antilock Brake System Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-hybrid-hp2-with-electronic-brake-distribution-vehicle-stability-system) for the ABS - Hybrid
  3. «Antilock Brake System Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-non-hybrid-less-than-3900-kg-8600-lb-gvw-with-ebd-vses) for the ABS - Non-Hybrid Less than 3900 kg (8600 lb) GVW
  4. «Antilock Brake System Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-non-hybrid-greater-thanequal-to-3900-kg-8600-lb-gvw-with-tcs-ves) for the ABS - Non-Hybrid Greater than/Equal to 3900 kg (8600 lb) GVW

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition OFF, disconnect the harness connector of the yaw rate sensor.
  2. Ignition ON, verify that a test lamp illuminates between the module voltage circuit and ground. If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
  3. Ignition OFF, test for less than 5 ohms between the module ground circuits and ground. If greater than the specified value, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.
  4. If all circuits test normal, replace the yaw rate sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «ABS Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-hybrid-hp2-with-electronic-brake-distribution-vehicle-stability-system__abs-description-and-operation) for the ABS - Hybrid
  3. «Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-non-hybrid-less-than-3900-kg-8600-lb-gvw-with-ebd-vses) for the ABS - Non-Hybrid Less than 3900 kg (8600 lb) GVW
  4. «Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-non-hybrid-less-than-3900-kg-8600-lb-gvw-with-ebd-vses) for the ABS - Non-Hybrid Greater than/Equal to 3900 kg (8600 lb) GVW
  5. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming

Symptoms - Data Communications

Note. The following steps must be completed before using the symptom tables.

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) before using the symptom tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data links.
  2. Review the system operation in order to familiarize yourself with the system functions. Refer to «Data Link Communications Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .

Visual/Physical Inspection

  1. Inspect for aftermarket devices which could affect the operation of the systems. Refer to «Checking Aftermarket Accessories»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__checking-aftermarket-accessories) .
  2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

  1. «Scan Tool Does Not Power Up»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  3. «Scan Tool Does Not Communicate with Low Speed GMLAN Device»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  4. «Scan Tool Does Not Communicate with Powertrain High Speed GMLAN Device»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
DLC B+11
DLC Ground1
1. Scan Tool Does Not Power Up

The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following

  1. Scan tool B+ voltage at terminal 16
  2. Scan tool ground at terminal 4
  3. Common ground at terminal 5
  1. The scan tool will power up with the ignition OFF. Some modules however, will not communicate unless the ignition is ON and the power mode master (PMM) module sends the appropriate power mode message.
  2. If the B+ circuit, ground circuits, and connections of the DLC are functioning properly, the malfunction must be due to the scan tool/CANdi module.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information.

  1. Test for less than 2.0 ohms between the ground circuits terminal 4 of the DLC and ground, and terminal 5 of the DLC and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 16 at the DLC and ground. If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance.
  3. If all circuits test normal, refer to the scan tool/CANdi module user guide.

Perform the Diagnostic Repair Verification after completing the repair.

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
High Speed GMLAN Serial Data (+)1U0100-U0299*1
High Speed GMLAN Serial Data (-)1U0100-U0299*1
Ground (DLC, terminal 5)1
* No communications with one or more high speed GMLAN modules. An open in only one high speed GMLAN serial data circuit may allow degraded communication between the modules. An open between the data link connector (DLC) and the first splice will only effect the communication with the scan tool. The vehicle modules will still communicate. 1. No communication with any high speed GMLAN module

The serial data is transmitted on two twisted wires that allow speeds up to 500 Kb/s. The twisted pair is terminated with two 120 ohms resistors, one is internal to the engine control module (ECM) and the other can be a separate resistor in a connector assembly or in another control module. The resistors are used as the load for the High Speed GMLAN buss during normal vehicle operation. The high speed GMLAN is a differential bus. The high speed GMLAN serial data bus (+) and high speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level of approximately 2.5 V. Driving the lines to their extremes, adds one volt to the high speed GMLAN serial data bus (+) circuit and subtracts one volt from the high speed GMLAN serial data bus (-) circuit. If serial data is lost, control modules will set a no communication code against the non-communicating control module. Note that a loss of serial data DTC does not represent a failure of the module that set it.

  1. Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated "current" or "active" status. Loss-of-communication U-codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios: A control module on the data communication circuit was disconnected while the communication circuit is awake. Power to one or more modules was interrupted during diagnosis A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold. Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialize at the same time. If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.
  2. Do not replace a control module reporting a U-code. The U-code identifies which control module needs to be diagnosed for a communication issue.
  3. Communication may be available between the BCM and the scan tool with the high speed GMLAN serial data system inoperative. This condition is due to the BCM using both the high and low speed GMLAN systems.
  4. An open in the DLC ground circuit terminal 5 will allow the scan tool to operate but not communicate with the vehicle. When the scan tool attempts to communicate with the vehicle a message "no CANdi module detected" will be displayed.
  5. The engine will not start when there is a total malfunction of the high speed GMLAN serial data bus.
  6. Technicians may find various Local Area Network (LAN) communication Diagnostic Trouble Codes (DTC) and no low speed GMLAN communications with the scan tool.
  7. The engine will not start when there is a total malfunction of the high speed GMLAN serial data bus. These conditions may be caused by the installation of an aftermarket navigation radio module (see bulletins). Some customers may comment of one or more of the following concerns: Vehicle will not crank. Vehicle cranks but will not start. Vehicle stability enhancement system warning lights and messages. PRNDL gear indicator position errors. Tire Pressure Monitor (TPM) system warning lights.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Note. Each control module may need to be disconnected to isolate a circuit fault. Use the schematic to identify the following: Control modules the vehicle is equipped with High speed GMLAN serial data circuit terminating resistors Control module locations on the high speed GMLAN serial data circuits Each control module's high speed GMLAN serial data circuit terminals

  1. Attempt to communicate with all control modules on the high speed GMLAN serial data circuit, refer to «Data Link References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system__data-link-references) . Communications should not be available with two or more control modules on the high speed GMLAN serial data circuit. If only one control module is not communicating, diagnose that control module only; refer to «DTC U0100-U02FF (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «DTC U0100-U02FF (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .
  2. Disconnect the scan tool from the DLC. The following tests will be done at the DLC connector.
  3. All access doors closed, ignition OFF for 60 seconds, test for less than 10 ohms between the ground circuit terminal 5 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, test for less than 4.5 V between the serial data circuits listed below and ground: Terminal 6 Terminal 14 If greater than the specified range, test the serial data circuit for a short to voltage; refer to Testing the Serial Data Circuits for a Short to Voltage.
  5. Ignition OFF for 60 seconds, test for greater than 100 ohms between the serial data circuits listed below and ground: Terminal 6 Terminal 14 If not the specified value, test the serial data circuit for a short to ground; refer to Testing the Serial Data Circuits for a Short to ground.
  6. Test for 50-70 ohms between the serial data circuits terminal 6 and terminal 14. If less than 35 ohms, test for a short between the serial data circuits; refer to Testing the Serial Data Circuits for a Short between the Circuits. If 35-50 ohms there may be a third terminating resistor between the serial data circuits. This can happen if the incorrect control module is installed. Some control modules are available with and without the terminating resistors installed to reduce the need of terminating resistors in the wiring harness. If greater than 70 ohms but less than infinite, test the serial data circuit for an open/high resistance; refer to Testing the Serial Data Circuits for an Open/High Resistance. If infinite, test the serial data circuits between the DLC and the first connection to the serial data circuit for an open/high resistance.

Testing the Serial Data Circuits for a Short to Voltage

  1. Ignition OFF, disconnect the harness connectors with the high speed GMLAN serial data circuits at an easily accessible control module.
  2. Ignition ON, test for greater than 4.5 V between each serial data circuit at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are greater than 4.5 V. If all serial data circuits are less than the specified range, replace the control module that was disconnected.
  3. Ignition OFF, disconnect the harness connectors with the high speed GMLAN serial data circuits at another control module, in the direction of the circuit shorted to voltage.
  4. Ignition ON, test for greater than 4.5 V between the serial data circuits at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are greater than 4.5 V. If all serial data circuits are less than the specified range, replace the control module that was just disconnected.
  5. Repeat step 3 until one of the follow conditions are isolated: A short to voltage on the serial data circuit between 2 control modules A short to voltage on the serial data circuit between a control module and a terminating resistor.

Testing the Serial Data Circuits for a Short to Ground

  1. Ignition OFF, disconnect the harness connectors with the high speed GMLAN serial data circuits at an easily accessible control module.
  2. Ignition OFF for 60 seconds, test for less than 1k ohms between each serial data circuit at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are less than 1k ohms. If all serial data circuits are greater than the specified range, replace the control module that was disconnected.
  3. Disconnect the harness connectors with the high speed GMLAN serial data circuits at another control module, in the direction of the circuit shorted to ground.
  4. Ignition OFF for 60 seconds, test for less than 1k ohms between the serial data circuits at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are less than 1k ohms. If greater than the specified range for all serial data circuits, replace the control module that was just disconnected.
  5. Repeat step 3 until one of the follow conditions are isolated: A short to ground on the serial data circuit between 2 control modules A short to ground on the serial data circuit between a control module and a terminating resistor

Testing the Serial Data Circuits for a Short between the Circuits

  1. Ignition OFF, disconnect the harness connectors with the high speed GMLAN serial data circuits at an easily accessible control module that is not communicating.
  2. Ignition OFF for 60 seconds, test for less than 35 ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 ohms. If each pair of serial data circuits is greater than the specified range, replace the control module that was disconnected.
  3. Connect the harness connectors at the control module that was disconnected.
  4. Disconnect the harness connectors with the high speed GMLAN serial data circuits at another control module, in the direction of the circuits shorted together.
  5. Ignition OFF for 60 seconds, test for less than 35 ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 ohms. If each pair of serial data circuits is within the specified range, replace the control module that was just disconnected.
  6. Repeat step 3 until one of the following conditions are isolated: Serial data circuits shorted together between 2 control modules Serial data circuits shorted together between a control module and a terminating resistor A shorted terminating resistor

Testing the Serial Data Circuits for an Open/High Resistance

  1. Ignition OFF, disconnect the harness connectors with the high speed GMLAN serial data circuits at an easily accessible control module that is not communicating.
  2. Ignition OFF for 60 seconds, test for greater than 100k ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are greater than 100k ohms. If each pair of serial data circuits is less than the specified range, replace the control module that was disconnected.
  3. Connect the harness connectors at the control module that was disconnected.
  4. Disconnect the harness connectors with the high speed GMLAN serial data circuits at another control module, in the direction of the open circuit.
  5. Ignition OFF for 60 seconds, test for greater than 100k ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are greater than 100k ohms. If each pair of serial data circuits is less than the specified range, replace the control module that was just disconnected.
  6. Repeat step 3 until one of the following conditions are isolated: An open/high resistance on the serial data circuit between 2 control modules An open/high resistance on the serial data circuit between a control module and a terminating resistor An open/high resistance terminating resistor

Perform the Diagnostic Repair Verification after completing the repair.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for control module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Low Speed GMLAN Serial Data (+)12*1
Ground (DLC, terminal 5)1*
* An open between the data link connector (DLC) and JX 200, or DLC terminal 5 ground will only effect the communication with the scan tool. See Diagnostic Aids. 1. No communication on any low speed GMLAN module 2. No communication on a specific low speed GMLAN module, or group of modules

Modules connected to the low speed GMLAN serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules when the ignition switch is in any position other than OFF. The low speed GMLAN serial data circuit uses JX 200, JX 300, and, if equipped, JX 201 as common connection points between some modules and the data link connector (DLC).

  1. Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated "current" or "active" status. Loss-of-communication U-codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios: A control module on the data communication circuit was disconnected while the communication circuit is awake. Power to one or more modules was interrupted during diagnosis A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold. Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialize at the same time. If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.
  2. Do not replace a control module reporting a U-code. The U-code identifies which control module needs to be diagnosed for a communication issue.
  3. Communication may be available between the BCM and the scan tool with the high speed GMLAN serial data system inoperative. This condition is due to the BCM using both the high and low speed GMLAN systems.
  4. An open in the DLC ground circuit terminal 5 will allow the scan tool to operate but not communicate with the vehicle. When the scan tool attempts to communicate with the vehicle a message "no CANdi module detected" will be displayed.
  5. The engine will not start when there is a total malfunction of the high speed GMLAN serial data bus.
  6. Technicians may find various Local Area Network (LAN) communication Diagnostic Trouble Codes (DTC) and no low speed GMLAN communications with the scan tool.
  7. The engine will not start when there is a total malfunction of the high speed GMLAN serial data bus. These conditions may be caused by the installation of an aftermarket navigation radio module (see bulletins). Some customers may comment of one or more of the following concerns: Vehicle will not crank. Vehicle cranks but will not start. Vehicle stability enhancement system warning lights and messages. PRNDL gear indicator position errors. Tire Pressure Monitor (TPM) system warning lights.

Schematic Reference

Connector End View Reference

  1. «Component Connector End Views»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index-a)
  2. «Splice Pack Connector End Views»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#wiring-systems-and-power-management-splice-pack-connector-end-views)

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Note. Use the schematic to identify the following: Control modules the vehicle is equipped with Control module locations on the low speed GMLAN serial data circuit Each control module's low speed GMLAN serial data circuit terminals

  1. Attempt to communicate with all control modules on the low speed GMLAN serial data circuit, refer to «Data Link References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system__data-link-references) . Communications should not be available with two or more control modules on the low speed GMLAN serial data circuit. If only one control module is not communicating, diagnose that control module only, refer to «DTC U0100-U02FF (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «DTC U0100-U02FF (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) . If one or more control modules are communicating but not all, refer to Testing the Serial Data Circuit for an Open/High Resistance.
  2. Disconnect the scan tool from the DLC. The following tests will be done at the DLC connector.
  3. All access doors closed, ignition OFF for 60 seconds, test for less than 10 ohms between the ground circuit terminal 5 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, test for less than 4.5 V between the serial data circuit terminal 1 and ground. If greater than the specified range, test the serial data circuit for a short to voltage, refer to Testing the Serial Data Circuit for a Short to Voltage.
  5. Ignition OFF for 60 seconds, test for greater than 100 ohms between the serial data circuit terminal 1 and ground. If not the specified value, test the serial data circuit for a short to ground, refer to Testing the Serial Data Circuits for a Short to ground.
  6. Disconnect the harness connector at the JX 200 splice pack.
  7. Test for less than 2 ohms between the serial data circuit terminal 1 and the JX 200 splice pack terminal D. If greater than the specified range, test the serial data circuit for an open/high resistance. If the circuits test normal, replace the splice pack.

Testing the Serial Data Circuits for a Short to Voltage

  1. Ignition OFF, disconnect the harness connectors at the JX 200, JX 300, and JX 201 splice packs, as equipped.
  2. Ignition ON, test for less than 4.5 V between the DLC serial data circuit terminal 1 and ground. If greater than the specified range, repair the short to voltage.
  3. Test for less than 4.5 V between each serial data circuit and ground. If greater than the specified range, perform the appropriate test listed below
  1. Serial data circuits with one control module, test the serial data circuit for a short to voltage. If the circuit tests normal replace the control module.
  2. Serial data circuits with 2 or more control modules, test each section of the serial data circuit for a short to voltage. If the circuits test normal, replace the control module that causes the short to voltage when connected.

Testing the Serial Data Circuits for a Short to Ground

  1. Ignition OFF, disconnect the harness connectors at the JX 200, JX 300, and JX 201 splice packs, as equipped.
  2. Test for infinite resistance between the DLC serial data circuit terminal 1 and ground. If not the specified value, repair the short to ground.
  3. Ignition OFF for 60 seconds, test for greater than 100 ohms between each serial data circuit and ground. If less than the specified range, perform the appropriate test listed below
  1. Serial data circuits with one control module, test the serial data circuit for a short to ground. If the circuit tests normal replace the control module.
  2. Serial data circuits with 2 or more control modules, test each section of the serial data circuit for a short to ground. If the circuits test normal, replace the control module that causes the short to ground when connected.

Testing the Serial Data Circuit for an Open/High Resistance

  1. If equipped with a JX 300 splice pack, ignition ON, verify the scan tool communicates with one or more control modules connected to the JX 300 splice pack. If all control modules on the JX 300 spice pack do not communicate, test the serial data circuit between the JX 200 and JX 300 splice packs for an open/high resistance. If the circuit tests normal, test each splice pack for an open/high resistance.
  2. Ignition OFF, disconnect one of the harness connectors listed below: JX 200 if the control modules not communicating are connected to the JX 200 splice pack JX 201 if the control modules not communicating are connected to the JX 201 splice pack, if equipped JX 300 if the control modules not communicating are connected to the JX 300 splice pack
  3. Install a 3A fused jumper wire between the disconnected splice pack terminal 1 and a low speed GMLAN serial data circuit that is not communicating.
  4. Ignition ON, verify the scan tool communicates with the control modules connected to the low speed GMLAN serial data circuit. If any control module does not communicate, test each section of the serial data circuit for an open/high resistance. If the circuits test normal, replace the control module that does not communicate when connected.

Perform the Diagnostic Repair Verification after completing the repair.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Powertrain High Speed GMLAN Serial Data (+)1U0100-U0299*1
Powertrain High Speed GMLAN Serial Data (-)1U0100-U0299*1
Ground (DLC, terminal 5)1
* No communications with one or more Powertrain High Speed GMLAN modules. An open in only one Powertrain High Speed GMLAN serial data circuit may allow degraded communication between the modules. An open between the data link connector (DLC) and the first splice will only effect the communication with the scan tool. The vehicle modules will still communicate. 1. No communication with any Powertrain High Speed GMLAN module

The serial data is transmitted on two twisted wires that allow speeds up to 500 Kb/s. The twisted pair is terminated with two 120 ohms resistors, one is internal to the engine control module (ECM) and the other can be a separate resistor in a connector assembly or in another control module. The resistors are used as the load for the Powertrain High Speed GMLAN buss during normal vehicle operation. The Powertrain High Speed GMLAN is a differential bus. The Powertrain High Speed GMLAN serial data bus (+) and Powertrain High Speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level of approximately 2.5 V. Driving the lines to their extremes, adds one volt to the Powertrain High Speed GMLAN serial data bus (+) circuit and subtracts one volt from the Powertrain High Speed GMLAN serial data bus (-) circuit. If serial data is lost, control modules will set a no communication code against the non-communicating control module. Note that a loss of serial data DTC does not represent a failure of the module that set it.

  1. Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated "current" or "active" status. Loss-of- communication U-codes such as these can set for a variety of reasons. Many times, they're transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios: A control module on the data communication circuit was disconnected while the communication circuit is awake. Power to one or more modules was interrupted during diagnosis A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold. Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialize at the same time. If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.
  2. Do not replace a control module reporting a U code. The U code identifies which control module needs to be diagnosed for a communication issue.
  3. Communication may be available between the BCM and the scan tool with the Powertrain High Speed GMLAN serial data system inoperative. This condition is due to the BCM using both the high and low speed GMLAN systems.
  4. An open in the DLC ground circuit terminal 5 will allow the scan tool to operate but not communicate with the vehicle. When the scan tool attempts to communicate with the vehicle a message "no CANdi module detected" will be displayed.
  5. The engine will not start when there is a total malfunction of the Powertrain High Speed GMLAN serial data bus.
  6. Technicians may find various Local Area Network (LAN) communication Diagnostic Trouble Codes (DTC) and no low speed GMLAN communications with the scan tool.
  7. The engine will not start when there is a total malfunction of the high speed GMLAN serial data bus. These conditions may be caused by the installation of an aftermarket navigation radio module (see bulletins). Some customers may comment of one or more of the following concerns: Vehicle will not crank. Vehicle cranks but will not start. Vehicle stability enhancement system warning lights and messages. PRNDL gear indicator position errors. Tire Pressure Monitor (TPM) system warning lights.

Schematic Reference

  1. «Data Communication Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Note. Each control module may need to be disconnected to isolate a circuit fault. Use the schematic to identify the following: Control modules the vehicle is equipped with Powertrain High Speed GMLAN serial data circuit terminating resistors Control module locations on the Powertrain High Speed GMLAN serial data circuits Each control module's Powertrain High Speed GMLAN serial data circuit terminals

  1. Attempt to communicate with all control modules on the Powertrain High Speed GMLAN serial data circuit, refer to «Data Link References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system__data-link-references) . Communications should not be available with two or more control modules on the Powertrain High Speed GMLAN serial data circuit. If only one control module is not communicating, diagnose that control module only; refer to «DTC U0100-U02FF (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) or «DTC U0100-U02FF (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#data-communication-system) .
  2. Disconnect the scan tool from the DLC. The following tests will be done at the DLC connector.
  3. All access doors closed, ignition OFF for 60 seconds, test for less than 10 ohms between the ground circuit terminal 5 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, test for less than 4.5 V between the serial data circuits listed below and ground: Terminal 3 Terminal 11 If greater than the specified range, test the serial data circuit for a short to voltage; refer to Testing the Serial Data Circuits for a Short to Voltage.
  5. Ignition OFF for 60 seconds, test for greater than 100 ohms between the serial data circuits listed below and ground: Terminal 3 Terminal 11 If not the specified value, test the serial data circuit for a short to ground; refer to Testing the Serial Data Circuits for a Short to ground.
  6. Test for 50-70 ohms between the serial data circuits terminal 3 and terminal 11. If less than 35 ohms, test for a short between the serial data circuits; refer to Testing the Serial Data Circuits for a Short between the Circuits. If 35-50 ohms there may be a third terminating resistor between the serial data circuits. This can happen if the incorrect control module is installed. Some control modules are available with and without the terminating resistors installed to reduce the need of terminating resistors in the wiring harness. If greater than 70 ohms but less than infinite, test the serial data circuit for an open/high resistance; refer to Testing the Serial Data Circuits for an Open/High Resistance. If infinite, test the serial data circuits between the DLC and the first connection to the serial data circuit for an open/high resistance.

Testing the Serial Data Circuits for a Short to Voltage

  1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control module.
  2. Ignition ON, test for greater than 4.5 V between each serial data circuit at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are greater than 4.5 V. If all serial data circuits are less than the specified range, replace the control module that was disconnected.
  3. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of the circuit shorted to voltage.
  4. Ignition ON, test for greater than 4.5 V between the serial data circuits at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are greater than 4.5 V. If all serial data circuits are less than the specified range, replace the control module that was just disconnected.
  5. Repeat step 3 until one of the follow conditions are isolated: A short to voltage on the serial data circuit between 2 control modules A short to voltage on the serial data circuit between a control module and a terminating resistor.

Testing the Serial Data Circuits for a Short to Ground

  1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control module.
  2. Ignition OFF for 60 seconds, test for less than 1k ohms between each serial data circuit at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are less than 1k ohms. If all serial data circuits are greater than the specified range, replace the control module that was disconnected.
  3. Disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of the circuit shorted to ground.
  4. Ignition OFF for 60 seconds, test for less than 1k ohms between the serial data circuits at the control module connector that was just disconnected and ground. Verify that one or more serial data circuits are less than 1k ohms. If greater than the specified range for all serial data circuits, replace the control module that was just disconnected.
  5. Repeat step 3 until one of the follow conditions are isolated: A short to ground on the serial data circuit between 2 control modules A short to ground on the serial data circuit between a control module and a terminating resistor.

Testing the Serial Data Circuits for a Short between the Circuits

  1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control module that is not communicating.
  2. Ignition OFF for 60 seconds, test for less than 35 ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 ohms. If each pair of serial data circuits is greater than the specified range, replace the control module that was disconnected.
  3. Connect the harness connectors at the control module that was disconnected.
  4. Disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of the circuits shorted together.
  5. Ignition OFF for 60 seconds, test for less than 35 ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 ohms. If each pair of serial data circuits is within the specified range, replace the control module that was just disconnected.
  6. Repeat step 3 until one of the following conditions are isolated: Serial data circuits shorted together between 2 control modules Serial data circuits shorted together between a control module and a terminating resistor A shorted terminating resistor

Testing the Serial Data Circuits for an Open/High Resistance

  1. Ignition OFF, disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at an easily accessible control module that is not communicating.
  2. Ignition OFF for 60 seconds, test for greater than 100k ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are greater than 100k ohms. If each pair of serial data circuits is less than the specified range, replace the control module that was disconnected.
  3. Connect the harness connectors at the control module that was disconnected.
  4. Disconnect the harness connectors with the Powertrain High Speed GMLAN serial data circuits at another control module, in the direction of the open circuit.
  5. Ignition OFF for 60 seconds, test for greater than 100k ohms between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are greater than 100k ohms. If each pair of serial data circuits is less than the specified range, replace the control module that was just disconnected.
  6. Repeat step 3 until one of the following conditions are isolated: An open/high resistance on the serial data circuit between 2 control modules An open/high resistance on the serial data circuit between a control module and a terminating resistor An open/high resistance terminating resistor

Perform the Diagnostic Repair Verification after completing the repair.

  1. «GMLAN Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for control module replacement, setup, and programming

Data Link References

This table identifies which serial data link that a particular module uses for in-vehicle data transmission. Some modules may use more than one data link to communicate. Some modules may have multiple communication circuits passing through them without actively communicating on that data link. This table is used to assist in correcting a communication malfunction. For the description and operation of these serial data communication circuits refer to Data Link Communications Description and Operation .

Control ModuleData Link TypeDiagnostic Procedure
Schematic Reference: Data Communication Schematics
Accessory DC Power Control Module w/ HP2Powertrain High Speed GMLANScan Tool Does Not Communicate with Powertrain High Speed GMLAN Device
AC Compressor w/ HP2Low Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Assist Step Control ModuleLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Audio AmplifierLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Body Control Module (BCM)High Speed GMLAN Low Speed GMLAN Local Interconnect Network (LIN)Scan Tool Does Not Communicate with High Speed GMLAN Device Scan Tool Does Not Communicate with Low Speed GMLAN Device DTC U1500, U1511, U1512, or U1513
Digital Radio ReceiverLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Drive Motor Generator Battery Control Module w/ HP2High Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device
Drive Motor Generator Power Inverter Module w/ HP2Powertrain High Speed GMLAN High Speed GMLANScan Tool Does Not Communicate with Powertrain High Speed GMLAN Device Scan Tool Does Not Communicate with High Speed GMLAN Device
Door Lock/Window Switch - DriverLow Speed GMLAN Local Interconnect Network (LIN)Scan Tool Does Not Communicate with Low Speed GMLAN Device DTC U1500, U1511, U1512, or U1513
Door Lock/Window Switch - PassengerLow Speed GMLAN Local Interconnect Network (LIN)Scan Tool Does Not Communicate with Low Speed GMLAN Device DTC U1500, U1511, U1512, or U1513
Electronic Brake Control Module (EBCM)High Speed GMLAN Powertrain High Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device Scan Tool Does Not Communicate with Powertrain High Speed GMLAN Device
Electronic Compass ModuleLocal Interconnect Network (LIN)DTC U1500, U1511, U1512, or U1513
Electronic Power Steering Motor Control Module w/ HP2High Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device
Electronic Suspension Control (ESC) ModuleHigh Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device
Engine / Powertrain Control Module (ECM/PCM)High Speed GMLAN Powertrain High Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device Scan Tool Does Not Communicate with Powertrain High Speed GMLAN Device
Fuel Pump Flow Control ModuleHigh Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device
Heated Seat Module - RearLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
HVAC Control ModuleLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Inflatable Restraint Sensing and Diagnostic Module (SDM)Low Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Inflatable Restraint Vehicle Rollover SensorLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Inside Rearview Mirror (ISRVM)Low Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Instrument Panel Cluster (IPC)Low Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Memory Seat Module (MSM)Low Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Object Alarm ModuleLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Passenger Presence System (PPS) ModuleLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Power Liftgate ModuleLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
RadioLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Rear Seat Audio (RSA) ControlLow Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Remote Control Door Lock Receiver (RCDLR)Low Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Serial Data Gateway Module (SDGM) w/ HP2Powertrain High Speed GMLAN High Speed GMLAN Low Speed GMLANScan Tool Does Not Communicate with Powertrain High Speed GMLAN Device Scan Tool Does Not Communicate with High Speed GMLAN Device Scan Tool Does Not Communicate with Low Speed GMLAN Device
Theft Deterrent Module (TDM)Low Speed GMLANScan Tool Does Not Communicate with Low Speed GMLAN Device
Trailer Brake Control ModuleHigh Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device
Transfer Case Shift Control ModuleHigh Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device
Transmission Control Module (TCM)High Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device
Vehicle Communication Interface Module (OnStar® VCIM)High Speed GMLAN - pass through only Low Speed GMLANScan Tool Does Not Communicate with High Speed GMLAN Device Scan Tool Does Not Communicate with Low Speed GMLAN Device
Window Motor - DriverLocal Interconnect Network (LIN)DTC U1500, U1511, U1512, or U1513
Window Motor - PassengerLocal Interconnect Network (LIN)DTC U1500, U1511, U1512, or U1513
Yaw and Lateral Accelerometer Sensor w/ HP2Powertrain High Speed GMLANScan Tool Does Not Communicate with Powertrain High Speed GMLAN Device

Scheme 18

Scheme 18: Auxiliary Body Control Module Replacement (Domestic)
Scheme 18: Auxiliary Body Control Module Replacement (Domestic)
CalloutComponent Name
Preliminary Procedures: Remove the inflatable restraint module. Refer to Instrument Panel Inflatable Restraint Module Replacement .
1Auxiliary Body Control Module Procedure Press on the tabs to release the auxiliary body control module. Disconnect the electrical connectors. Reprogram the auxiliary body control module if replaced. Refer to Control Module References .

Scheme 19

Scheme 19: Auxiliary Body Control Module Replacement (Export)
Scheme 19: Auxiliary Body Control Module Replacement (Export)
CalloutComponent Name
Preliminary Procedure: Remove the knee bolster. Refer to Knee Bolster Replacement (Cadillac) or Knee Bolster Replacement (Except Cadillac)
1Auxiliary Body Control Module Procedure Disconnect the electrical connectors. Press on the tabs to release the auxiliary body control module. If a replacement module is installed, program the module. Refer to Control Module References .

Scheme 20

Scheme 20: Body Control Module Replacement
Scheme 20: Body Control Module Replacement
CalloutComponent Name
Preliminary Procedure: Remove the knee bolster. Refer to Knee Bolster Replacement (Cadillac) or Knee Bolster Replacement (Except Cadillac)
1Body Control Module Tip: Remove the BCM cover. Disconnect the electrical connectors. Press on the tabs to release the body control module. If a replacement module is installed, program the module. Refer to Control Module References .

Serial Data Gateway Module Replacement (HP2)

CalloutComponent Name
Preliminary Procedures: Remove the inflatable restraint module. Refer to Instrument Panel Inflatable Restraint Module Replacement .
1Serial Data Gateway Module Assembly Procedure Press on the tabs to release the serial data gateway module. Disconnect the electrical connectors. Reprogram the serial data gateway module if replaced. Refer to Control Module References .

Body Control System Description and Operation

The body control system consists of the body control module (BCM), communications, and various input and outputs. Some inputs, outputs and messages require other modules to interact with the BCM. The BCM also has discrete input and output terminals to control the vehicle's body functions. The BCM is wired to the high speed GMLAN serial data bus and the low speed GMLAN serial data bus and acts as a gateway between them.

Power Mode Master

This vehicles body control module (BCM) functions as the power mode master (PMM). The ignition switch is a low current switch with multiple discrete ignition switch signals to the PMM for determination the power mode that will be sent over the serial data circuits to the other modules that need this information, and so the PMM will activate relays and other direct outputs of the PMM as needed. Refer to Power Mode Description and Operation for a complete description of power mode functions.

Body Control Module

The various body control module (BCM) input and output circuits are described in the corresponding functional areas indicated on the BCM electrical schematics. Some BCM functions with the subsystems may be as a gateway only or as an enable for the system. The BCM related systems/subsystems include, but are not limited to the following

  1. Antilock Brake System (ABS)-Refer to «ABS Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-hybrid-hp2-with-electronic-brake-distribution-vehicle-stability-system__abs-description-and-operation) , «ABS Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-non-hybrid-less-than-3900-kg-8600-lb-gvw-with-ebd-vses__abs-description-and-operation) or «ABS Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/anti-locktraction-control/#antilock-brake-system-non-hybrid-greater-thanequal-to-3900-kg-8600-lb-gvw-with-tcs-ves__abs-description-and-operation) .
  2. Automatic Day-Night Mirror-Refer to «Automatic Day-Night Mirror Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/mirrors/#mirror-system) .
  3. Cruise Control System-Refer to «Cruise Control Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/cruise-control-systems/#cruise-control-system__cruise-control-description-and-operation) .
  4. Electrical Power Management (EPM)-Refer to «Electrical Power Management Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#battery-charging-system-and-starting-system) .
  5. Exterior Lighting-Refer to «Exterior Lighting Systems Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/exterior-lights/#lighting-system) .
  6. Horn System-Refer to «Horns System Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/horns/#horn-system) .
  7. HVAC-Refer to «Air Delivery Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation) and «Air Temperature Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation) .
  8. Instrument Cluster Indicator Control-Refer to «Instrument Cluster Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges) .
  9. Interior Lighting-Refer to «Interior Lighting Systems Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/exterior-lights/#lighting-system) .
  10. Power Door Lock System-Refer to «Power Door Locks Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/door-locks-anti-theft-systems/#door-lock-system-door-handles) .
  11. Rear Window Defogger System-Refer to «Rear Window Defogger Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/heated-glassdefoggers/#fixed-and-moveable-windows-system) .
  12. Redundant Steering Wheel Controls-Refer to «Steering Wheel Controls Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/memory-modules/#configurable-customer-control-system__steering-wheel-controls-description-and-operation) .
  13. Remote Function Actuation (RFA) Control-Refer to «Keyless Entry System Description and Operation (Without Accessory 2 Way Remote)»(/cadillac/escalade/gmt900-2006-2014/remont/door-locks-anti-theft-systems/#keyless-entry-system-and-remote-functions__keyless-entry-system-description-and-operation) or «Keyless Entry System Description and Operation (With Accessory 2 Way Remote)»(/cadillac/escalade/gmt900-2006-2014/remont/door-locks-anti-theft-systems/#keyless-entry-system-and-remote-functions__keyless-entry-system-description-and-operation) .
  14. Retained Accessory Power (RAP)-Refer to «Retained Accessory Power Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#wiring-systems-and-power-management-description-and-operation) .
  15. Shift Lock Control System-Refer to «Automatic Transmission Shift Lock Control Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/automatic-trans/#shift-interlock-system__automatic-transmission-shift-lock-control-description) .
  16. Starting System-Refer to «Starting System Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#battery-charging-system-and-starting-system__starting-system-description-and-operation) .
  17. Supplemental Inflatable Restraint (SIR) System-Refer to «SIR System Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/airbag/#supplemental-inflatable-restraint-system) .
  18. Suspension System-Refer to «Electronic Suspension Control Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/electronic-suspension/#suspension-control-system-suspension-damping) .
  19. Theft Deterrent-Refer to «Content Theft Deterrent (CTD) Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/door-locks-anti-theft-systems/#theft-deterrent-system__content-theft-deterrent-ctd-description-and) .
  20. Tire Pressure Monitor (TPM) System-Refer to «Tire Pressure Monitor Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/warning-system/#tire-pressure-monitoring-system__tire-pressure-monitor-description-and-operation) .
  21. Wiper/Washer System Functions-Refer to «Wiper/Washer System Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/wiperwasher-systems/#wiper-system-washer-system) .

Export Body Control Module

The export body control system has an additional body control module located in the rear of the vehicle. This additional body control module is referred to as the XBCM. The XBCM has discrete input and output terminals to control additional vehicle body functions not supported by the primary body control module (BCM). The XBCM is wired to the low speed GMLAN serial data bus and the BCM and acts as a gateway between them. If the XBCM does not communicate, various rear end lighting such as rear fog lamps and trailer lighting will be impaired.

The various input and output circuits are described in the corresponding functional areas indicated on the XBCM electrical schematics. Some XBCM functions with the subsystems may be as a gateway only or as an enable for the system. The XBCM related systems/subsystems include, but are not limited to the following

  1. Exterior lighting-Refer to «Exterior Lighting Systems Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/exterior-lights/#lighting-system) .
  2. Instrument cluster indicator control-Refer to «Instrument Cluster Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges) .
  3. Theft deterrent-Refer to «Content Theft Deterrent (CTD) Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/door-locks-anti-theft-systems/#theft-deterrent-system__content-theft-deterrent-ctd-description-and) .

The communication among control modules is performed through the high speed GMLAN serial data bus, the low speed GMLAN serial data bus, and with RPO HP2 the high speed hybrid GMLAN serial data bus. The modules that need real time communication are attached to the high speed GMLAN busses. There are several modules that act as the gateway module or translator for communication between the various serial data busses. With RPO HP2 the serial data gateway module (SDGM) is the gateway and on all others the body control module (BCM). All high speed modules are activated by a communication enable or wakeup circuit from another module as determined by the power mode master (PMM).

Refer to Data Communication Schematics to determine the circuit and module that activates specific high speed modules.

Signal supervision is the process of determining whether an expected signal is being received or not. Some messages are sent on a periodic basis and are interpreted as a heartbeat of a device. If such a signal is lost, the signal supervision part of the software will set a no communication DTC (U. code) against the missing device. This code is mapped on the Tech 2 screen as a code against the physical device. A lost communication DTC typically is set in modules other than the module with a communication failure.

Serial Data Reference

The scan tool communicates over the various busses on the vehicle. When a scan tool is installed on a vehicle, the scan tool will try to communicate with every module that could be optioned into the vehicle. If an option is not installed on the vehicle, the scan tool will display No COMM for that options specific control module.

In order to avert misdiagnoses of No Communication with a specific module, refer to Data Link References for a list of modules, the busses they communicate with, and the RPO codes for a specific module.

Serial Data Gateway w/o HP2

The body control module (BCM) in this vehicle functions as a gateway or translator. The purpose of the gateway is to translate serial data messages between the high speed GMLAN bus and the low speed GMLAN bus for communication between the various modules. The gateway will interact with each network according to that network's transmission protocol.

One example of this necessary communication is the communication between the engine control module (ECM)/powertrain control module (PCM) which is high speed serial data and Theft Deterrent Module which is low speed serial data. If these modules can not exchange information, the vehicle will not start.

A lost communication DTC typically is set in modules other than the module with a communication failure.

Serial Data Gateway w/HP2

The SDGM in this vehicle functions as a gateway or translator. The purpose of the gateway is to translate serial data messages between the high speed GMLAN serial data bus, the low speed GMLAN serial data bus, and the high speed hybrid GMLAN serial data bus for communication between the various modules. The gateway will interact with each network according to that network's transmission protocol.

High Speed GMLAN Circuit Description

The data link connector (DLC) allows a scan tool to communicate with the high speed GMLAN serial data modules. The serial data is transmitted on 2 twisted wires that allow speed up to 500 Kb/s. The twisted pair is terminated with two 120-ohm resistors, one is internal to the engine control module (ECM) and the other is after the electronic brake control module (EBCM), or if equipped, the suspension control module. The high speed GMLAN is a differential bus. The high speed GMLAN serial data bus (+) and high speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level. The idle level, which is approximately 2.5 volts, is considered recessive transmitted data and is interpreted as a logic 1. Driving the lines to their extremes, adds 1 volt to the high speed GMLAN serial data bus (+) and subtracts 1 volt from the high speed GMLAN serial data bus (-) wire. If a communication signal is lost, the application will set a no communication code against the respective control module. This code is mapped on the Tech 2 screen as a code against the physical device. Note: a loss of serial data DTC does not represent a failure of the module that the code is set in.

The high speed GMLAN serial data allows communication between the body control module (BCM), ECM, transmission control module (TCM), vehicle communication interface module (VCIM), 4WD control module, EBCM, and the suspension control module depending on RPO.

High Speed Hybrid GMLAN Circuit Description

The high speed hybrid GMLAN serial data modules do not communicate directly with the scan tool. The SDGM communicates on all serial data busses and relays the high speed hybrid GMLAN serial data information to the scan tool. The high speed hybrid GMLAN serial data bus operates the same as the high speed GMLAN bus with the exception of the need of the SDGM for communication between the modules and a scan tool.

Low Speed GMLAN Circuit Description

The data link connector (DLC) allows a scan tool to communicate with the low speed GMLAN serial data circuit. The serial data is transmitted over a single wire to the appropriate control modules. Under normal vehicle operating conditions, the speed of the bus is 33.33 Kb/s. This protocol produces a simple pulse train sent out over the low speed GMLAN serial data bus. When a module pulls the bus high, 5 volts, this creates a logic state of 0 on the bus. When the bus is pulled low, 0 volts, it is translated as a logic state of 1. To wake the control modules connected to the low speed GMLAN serial data bus, a wake up signal is sent out over the bus. Modules connected to the low speed GMLAN bus can be part of a virtual network as described in the other GMLAN circuit descriptions above. The modules on the low speed GMLAN serial data bus are connected to the bus using several splice or "star" connectors separating groups of modules. The following lists state the splices and modules connected to the low speed serial data circuits

I/P Splice

  1. Data link connector (DLC), connected only to the instrument panel (I/P) splice
  2. Amplifier (Amp)
  3. Rear seat audio (RSA)
  4. Vehicle communication interface module (VCIM)
  5. Digital radio receiver (DRR)
  6. Inside rearview mirror module (ISRVM), connected through the mid I/P fuse block
  7. Instrument panel cluster (IPC)
  8. Body control module (BCM)
  9. Theft deterrent module (TDM)
  10. Heater ventilation and air conditioning (HVAC)
  11. Radio
  12. Driver door switch (DDS), connected through the left I/P fuse block
  13. Passenger door switch (PDS), connected through the right I/P fuse block

Body Splice

  1. Articulating running board module (ARBM)
  2. Ultrasonic park assist (UPA)
  3. Memory seat module (MSM)
  4. Liftgate module (LGM)
  5. Passenger presence system (PPS)
  6. Inflatable restraint vehicle rollover sensor (ROS)
  7. Inflatable restraint sensing and diagnostic module (SDM)

Data Link Connector (DLC)

The data link connector (DLC) is a standardized 16-cavity connector. The DLC low speed serial data circuit is connected directly to the instrument panel (I/P) splice then to all other splices or modules. Connector design and terminal location is dictated by an industry wide standard, and is required to provide the following

  1. Terminal 1 low speed GMLAN communications terminal
  2. Terminal 4 scan tool power ground terminal
  3. Terminal 5 common signal ground terminal
  4. Terminal 6 high speed GMLAN serial data bus (+) terminal
  5. Terminal 14 high speed GMLAN serial data bus (-) terminal
  6. Terminal 16 scan tool power, battery positive voltage terminal

With RPO HP2 the DLC also connects the high speed hybrid GMLAN bus to the scan tool for programming purposes. The terminal and circuits are as follows

  1. Terminal 3 high speed hybrid GMLAN serial data bus (+) terminal
  2. Terminal 11 high speed hybrid GMLAN serial data bus (-) terminal

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Diagnostic Repair Verification
• Control Module References
• Component Connector End Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Hybrid Controls Schematics
• High Voltage Disabling
• Diagnostic Trouble Code (DTC) List - Vehicle
• GMLAN Wiring Repairs
• Instrument Cluster Schematics
• Front Side Door Window Regulator Motor Replacement
• Power Distribution Schematics
• Instrument Panel Center Trim Panel Replacement (Cadillac)
• Antilock Brake System Schematics
• ABS Description and Operation
• Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement
• Hybrid Energy Storage Schematics
• Antilock Brake System Schematics
• ABS Description and Operation
• Checking Aftermarket Accessories
• Splice Pack Connector End Views
• Instrument Panel Inflatable Restraint Module Replacement
• Power Mode Description and Operation
• ABS Description and Operation
• Automatic Day-Night Mirror Description and Operation
• Cruise Control Description and Operation
• Electrical Power Management Description and Operation
• Exterior Lighting Systems Description and Operation
• Horns System Description and Operation
• Air Delivery Description and Operation
• Air Temperature Description and Operation
• Power Door Locks Description and Operation
• Steering Wheel Controls Description and Operation
• Keyless Entry System Description and Operation (Without Accessory 2 Way Remote)
• Automatic Transmission Shift Lock Control Description and Operation
• Starting System Description and Operation
• Electronic Suspension Control Description and Operation
• Content Theft Deterrent (CTD) Description and Operation
• Tire Pressure Monitor Description and Operation
• Wiper/Washer System Description and Operation
• DTC B1000
• Data Link References
• Control Module U Code List

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