Computer/integrating Systems Cadillac STS I

Computer/Integrating Systems Schematic Icons Icon Icon Definition CAUTION: When performing service on or near the SIR components or the SIR wiring, the SIR system must be disabled. Refer to SIR Disabling and Enabling Zones. Failure to observe the correct procedure could cause deployment of the SIR components, personal injury, or unnecessary SIR system repairs. IMPORTANT: Twisted-pair wires provide an effective shield that helps protect sensitive electronic components from electrical interference. In order to prevent electrical interference from degrading the performance of the connected components, you must maintain the proper specification when making any repairs to the twisted-pair wires shown : The wires must be twisted a minimum of 9 turns per 31 cm (12 in) as measured anywhere along the length of the wires. The outside diameter of the twisted wires must not exceed 6.0 mm (0.25 in)

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Data Link Connector (DLC) Connector End Connector Part Information OEM: 511161601 Service: Pin Wire Color Circuit No. Function 1 D-GN 5060 Low Speed GMLAN Serial Data 2-3 - - Not Used 4 BK 350 Ground 5 BK/WH 351 Ground 6 TN/BK 2500 High Speed GMLAN Serial Data (+) (1) 7-13 - - Not Used 14 TN 2501 High Speed GMLAN Serial Data (-) (1) 15 - - Not Used 16 RD/WH 1140 Battery Positive Voltage Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe

Instrument Panel Module (IPM) - C1 Connector End Connector Part Information OEM: 1318757-1 Service: 26-Way M 90 Series (WH) Pin Wire Color Circuit No. Function 1 YE 32 Instrument Panel Lamp Fuse Supply Voltage (1) 2 YE 1491 Backlight Lamp Control 3 YE 6817 LED Backlight Dimming Control YE 6817 4 - - Not Used 5 WH 17 Stop Lamp Switch Signal 6 PK 3 Run/Crank Ignition 1 Voltage 7 - - Not Used 8 YE/BK 5728 ECM/TCM Serial Data Wake Up 9 YE 5727 High Speed GMLAN Serial Data Wake Up 10 PK 5722 Ignition Mode Switch LED Supply Voltage 11 D-GN 5525 Tap Up/Tap Down Enable Signal 12 WH 111 Hazard Switch Signal 13 BN 1356 Flash To Pass Switch Signal 14 BN/WH 301 Park Lamp Switch On Signal 15 L-GN 5724 Ignition Mode Switch Mode Control 16 D-BU 5719 Ignition Mode Switch Start LED Signal 17 L-GN 5720 Ignition Mode Switch Accessory LED Signal 19 L-BU 6857 Headlamp Automatic High Beam Dim Status 20 L-BU 1134 Park Brake Switch Signal 21 PK/BK 1597 Interior Lamp Switch On Signal 22 PU 1783 Twilight Sentinel Delay Signal 23 WH 103 Headlamp Switch On Signal 24 - - Not Used 25 PU 1375 Remote Radio Control Head Accessory Supply Voltage 26 OG 5721 Ignition Mode Switch Off LED Signal Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe

Instrument Panel Module (IPM) - C2 Connector End Connector Part Information OEM: 1318756-1 Service: 24-Way M TYCO (WH) Pin Wire Color Circuit No. Function 1 BN 4 Accessory Voltage 2 YE 6847 Shift Select Switch Park Supply Voltage 3 D-GN/WH 1317 Fog Lamp Relay Control 4 TN/WH 1969 Headlamp High Beam Relay Control 5 WH 1080 Park Lamp Relay Control 6 PK/WH 1970 Headlamp Low Beam Relay Control 7 OG 300 Run Ignition 3 Voltage 8 - - Not Used 9 TN 28 Horn Relay Control 10 TN 28 Horn Relay Control 11 GY 478 Windshield Wiper Switch Signal (2) 12 BN 253 Trunk Release Relay Control 13 GY 2096 Steering Column Tilt and Telescope Up Switch Signal 14 YE 2097 Steering Column Tilt and Telescope Down Switch Signal 15 D-BU 6856 Headlamp Automatic High Beam Dim Enable 16 WH 5741 Steering Column Lock Module Lock Enable Relay Control 17-18 - - Not Used 19 D-GN/WH 1932 Shift Select Switch Park Signal 20 WH 1538 Headlamp On With Wipers Signal 21 PK 2094 Steering Column Tilt and Telescope Forward Switch Signal 22 OG 2095 Steering Column Tilt and Telescope Rearward Switch Signal 23 D-GN 1399 RAP Relay Coil Supply Voltage 24 WH 2282 Headlamp Washer Relay Control Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe

Instrument Panel Module (IPM) - C3 Connector End Connector Part Information OEM: 1318758-1 Service: 30-Way M AMP Hybrid (WH) Pin Wire Color Circuit No. Function 1 RD/WH 1140 Battery Positive Voltage 2 RD/WH 3340 Battery Positive Voltage 3 BK/WH 151 Signal Ground 4 TN 2501 High Speed GMLAN Serial Data (-) (1) 5 TN/BK 2500 High Speed GMLAN Serial Data (+) (1) 6 D-GN 44 Instrument Panel Lamp Dimmer Switch Signal 7 PK 5076 Current Sensor Supply Voltage 8 WH 5075 Current Sensor Signal 9 BN 5077 Current Sensor Low Reference 10 BK/WH 451 Signal Ground 11 L-BU 187 Rear Fog Lamp Switch Signal 12 OG 192 Front Fog Lamp Switch Signal 13 L-BU/WH 1414 Left Front Turn Signal Switch Signal 14 TN/WH 99 Windshield Washer Fluid Level Sensor Signal 15 TN 2501 High Speed GMLAN Serial Data (-) (1) 16 TN/BK 2500 High Speed GMLAN Serial Data (+) (1) 17 BN 5360 Brake Apply Sensor Low Reference 18 D-BU 1796 Steering Column Radio Control Signal 19 L-BU/BK 1688 5 Volt Reference 20 GY 1884 Cruise Control Set/Coast/Resume/Accelerate Switch Signal 21 D-GN 5060 Low Speed GMLAN Serial Data 22 D-GN 5060 Low Speed GMLAN Serial Data 23 - - Not Used 24 L-BU 1485 Flash To Pass Switch Supply Voltage 25 D-BU/WH 1415 Right Front Turn Signal Switch Signal 26 BN/WH 1571 Traction Control Switch Signal (2) 27 WH 5359 Brake Apply Sensor Supply Voltage 28 YE 5361 Brake Apply Sensor Signal 29 L-GN/WH 5723 Ignition Mode Switch Mode Voltage 30 - - Not Used Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe

Rear Integration Module (RIM) - C1 Connector End Connector Part Information OEM: 174046-2 Service: 16-Way F 40 Series Multi Lock (BK) Pin Wire Color Circuit No. Function 1 D-GN 646 Reverse Relay Coil Feed 2 D-BU 1393 Courtesy Lamp Relay Coil Control 3 WH 193 Rear Defog Relay Control 4 TN 755 RAP Relay Coil Control 5-9 - - Not Used 10 YE 1977 Rear Fog Lamp Relay Control (Export) 11 L-BU 1344 Trunk Release Relay Output-Coil 12 BN/WH 1429 Standing Lamp Relay Feed 13-16 - - Not Used Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe

Rear Integration Module (RIM) - C2 Connector End Connector Part Information OEM: 174047-2 Service: 20-Way M Hinged Lock (BK) Pin Wire Color Circuit No. Function 1 - - Not Used 2 PK 1339 Run/Crank Ignition 1 Voltage 3 YE/BK 1334 Left Rear Turn Signal Lamp Supply Voltage 4 - - Not Used 5 L-BU 2380 Rear Parking Assist Chime Signal 6-8 - - Not Used 9 YE 5530 Hood Open Switch Signal 10 GY 112 Windshield Wiper Switch Low/Pulse Signal (Export) 11 YE 5058 Intrusion Sensor Armed Signal (Export) 12 TN/BK 5168 Power Sounder Enable Signal (Export) 13 D-GN/WH 1335 Right Rear Turn Signal Lamp Supply Voltage 14 PU 5531 Hood Closed Switch Signal 15-16 - - Not Used 17 D-BU/WH 149 Courtesy Lamp Supply Voltage 18 - - Not Used 19 OG/BK 744 Trunk Ajar Switch Signal 20 PU 5059 Intrusion Sensor Alarm On Signal (Export) Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe

Rear Integration Module (RIM) - C3 Connector End Connector Part Information OEM: 174045-2 Service: 12-Way M 40 Series Multi Lock (BK) Pin Wire Color Circuit No. Function 1 D-BU/WH 1315 Right Front Turn Signal Lamp Supply Voltage 2 L-BU/WH 1314 Left Front Turn Signal Lamp Supply Voltage 3 - - Not Used 4 RD/BK 542 Battery Positive Voltage 5-9 - - Not Used 10 D-GN 5060 Low Speed GMLAN Serial Data 11 - - Not Used 12 YE 18 Left Rear Stop/Turn Lamp Supply Voltage Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe

Rear Integration Module (RIM) - C4 Connector End Connector Part Information OEM: 173850-1 Service: 8-Way F 070 (WH) Pin Wire Color Circuit No. Function 1 - - Not Used 2 RD/BK 442 Battery Positive Voltage 3 GY 157 Interior Lamp Control 4 BK/WH 851 Signal Ground 5 YE 18 Left Rear Stop/Turn Lamp Supply Voltage 6 D-GN 19 Right Rear Stop/Turn Lamp Supply Voltage 7 RD/WH 540 Battery Positive Voltage 8 BK 850 Ground Terminal Part Information Terminal: Terminal Seal: Release Tool: Core Crimp: Insulation Crimp: Test Probe

Begin the system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check - Vehicle will provide the following information

1. The identification of the control modules which are not communicating.
2. The identification of any stored diagnostic trouble codes (DTCs) and their status.

The use of the Diagnostic System Check - Vehicle will identify the correct procedures to begin vehicle diagnosis. These must be performed before system DTC or symptom diagnosis.

Scan Tool Output Controls

Scan Tool Output Controls

Scan Tool Data List

Scan Tool Data List

Circuit Description

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

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC B1000 Electronic Control Unit (ECU) Performance

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B1000

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.

B1000 00

Any of the conditions detailed below for B1000 31-39

B1000 31

Checksum of the EEPROM or Flash memory at power-up is incorrect.

B1000 32

Failure to write to Flash Memory during the writing process

B1000 33

Failure to write to EEPROM or Flash memory

B1000 34

RAM failure

B1000 35

Failure of the Calibration sector of the Flash ROM. Checksum of the Flash Sector is incorrect.

B1000 36

Failure of the EEPROM. Checksum is incorrect.

B1000 37

Watchdog processor failure

B1000 38

1. BASS algorithm failure
2. Other software failures

B1000 39

1. Internal power supply failure
2. Internal yaw rate sensor failure
3. Internal temperature sensor failure
4. Forward looking sensor error

Action Taken When the DTC Sets

If any variant of the DTC B1000 was set as current, the respective module will stop working. Some indications to the driver may be displayed, function of the module that set the code.

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, without a repeat of the malfunction.

Diagnostic Aids

1. This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
2. If this DTC is retrieved as both a current and history DTC, replace the module.

DTC B1000

The remote control door lock receiver (RCDLR) provides a high side drive output for the ignition 1 voltage circuit. The RCDLR controls the Run/Crank relay when the backup power mode is enabled.

This diagnostic procedure supports the following DTC

DTC B1370 Device Ignition 1 (ON and START) Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B1370

1. Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.
2. Backup power mode is enabled.

Conditions for Setting the DTC

1. The RCDLR detects a short to ground in the ignition 1 voltage circuit when the output is active.
2. The RCDLR detects a short to battery or an open in the ignition 1 voltage circuit when the output is inactive.
3. Any of the condition above must be present for more than 0.375 seconds.

The RCDLR disables the output for the current ignition cycle when a short to ground is detected.

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.

DTC B1370

The instrument panel module (IPM) is the power mode master and the remote control door lock receiver (RCDLR) is the backup power mode master. Both modules receive information regarding ignition mode switch position from the ignition mode switch. IPM receives ignition mode switch position data through the IPM ignition mode data signal circuit.

This diagnostic procedure supports the following DTC

DTC B1380 Device Ignition ACCESSORY Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B1380

Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.

The IPM sets the code if it detects that the OFF/ACC contact of the ignition mode switch is closed for more than 30 seconds.

The IPM does not react to switch inputs of equal or lower priority until condition is cleared.

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.

The following can cause the code to set as history

1. An intermittent problem of the ignition mode switch
2. The ACC/OFF button of the ignition mode switch was pressed for more than 30 seconds.

DTC B1380

The instrument panel module (IPM) is the power mode master and the remote control door lock receiver (RCDLR) is the backup power mode master. Both modules receive information regarding ignition mode switch position from the ignition mode switch. IPM receives ignition mode switch position data through the IPM ignition mode data signal circuit.

This diagnostic procedure supports the following DTC

DTC B1385 Device Ignition START Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B1385

Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.

B1385 01

The IPM sets the code if it detects a short to battery on ignition mode switch signal circuit.

B1385 59

The IPM sets the code if it detects that the START contact of the ignition mode switch is closed for more than 30 seconds.

The IPM does not react to switch inputs until condition is cleared.

The IPM does not react to switch inputs of equal or lower priority until condition is cleared.

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.

The following can cause the code to set as history

1. An intermittent short to battery on ignition mode switch signal circuit.
2. An intermittent problem of the ignition mode switch
3. The START button of the ignition mode switch was pressed for more than 30 seconds.

DTC B1385

The instrument panel module (IPM) is the power mode master and the remote control door lock receiver (RCDLR) is the backup power mode master. The both modules receive the same information from ignition mode switch therefore are able to correctly discern all power modes. There is no degradation in vehicle operation when the backup power mode is active.

This diagnostic procedure supports the following DTC

DTC B1422 Device Power Moding Error

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B1422

Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.

The following conditions enable the backup power mode

1. The RCDLR detects a loss of the power mode message from the IPM.
2. The IPM invalidates the power mode message.
3. The RCDLR senses a change on its ignition mode switch inputs, twice, without receiving the corresponding message from the IPM.

The backup power mode becomes the system power mode. This code will set following the setting of the DTC B1440.

The Service Vehicle Soon (SVS) indicator will illuminate.

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.

The setting of this DTC can be caused by various failures

1. The ignition mode switch malfunction
2. The ignition mode data input circuits to IPM
3. The IPM malfunction

Test Description

The number below refers to the step number on the diagnostic table.

1. 2: The setting of any of those DTCs may be followed by the setting of B1422.

DTC B1422

The instrument panel module (IPM) is the power mode master and the remote control door lock receiver (RCDLR) is the backup power mode master. Both modules receive information regarding ignition mode switch position from the ignition mode switch. The ignition mode switch will be monitored only with battery voltage at or above 7 volts to prevent invalid input readings during low voltages encountered during vehicle cranking.

Four modes are discernible

1. Inactive
2. Start active
3. Off active
4. Short detect

This diagnostic procedure supports the following DTC

DTC B1440 Power Mode Master Input Circuits Mismatch

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B1440

Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.

B1440 03

The RCDLR detects a short to ground on its mode data input circuit, for more than 60 seconds.

B1440 08

1. The RCDLR input does not match the state of the mode switch received from the IPM.
2. The RCDLR receives a message from the IPM, indicating that a switch has been pressed, without seeing the corresponding input go active.
3. The RCDLR mode data input is active for more than 60 seconds, without seeing the corresponding message from the IPM.

The Service Vehicle Soon (SVS) indicator will illuminate. Also, the following scenarios may take place

1. If the RCDLR senses a change on its ignition mode data input, but does not receive the corresponding message from the IPM, the RCDLR will enable the backup power mode. The backup power mode will be the old power mode. If a second change is sensed by RCDLR on its ignition mode data input, without the corresponding message from the BCM, the backup power mode will be changed accordingly to signal sensed.
2. If the RCDLR receives a message from the IPM, indicating that a switch has been pressed, without sensing the change itself, the setting of the backup power moding will be disabled for the current ignition cycle.

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.

The setting of this DTC can be caused by various failures

1. The RCDLR malfunction
2. The IPM malfunction
3. The ignition mode switch malfunction
4. The ignition mode data input circuits to either RCDLR or IPM

The number below refers to the step number on the diagnostic table.

1. 3: This step checks for a proper reading of the ignition mode switch by the RCDLR.

DTC B1440

The instrument panel module (IPM) interfaces with an 8-position steering wheel resistive ladder. These switches are used for entertainment purposes and cruise control purposes if the vehicle is equipped with adaptive cruise control. The steering wheel switch network is fed by the remote radio control head ACC supply voltage. The return signal to the IPM is provided by steering column radio control signal circuit. The output voltage must be read by an A/D in order to carry out a ratiometric read which will be used to determine which, if any, switch has been activated.

This diagnostic procedure supports the following DTC

DTC B3622 Steering Wheel Controls Signal Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC B3622

1. Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.
2. IPM in Accessory, Run or Crank power modes.

B3622 01

The IPM detects a short to voltage on steering column radio control signal circuit, for more than 5 seconds.

B3622 08

The IPM detected signal from the steering column radio control signal circuit doesn't fall into a calibrated range.

B3622 59

The IPM detects that any of the steering wheel control switches is stuck, for more than 30 seconds.

B3622 01 and 08

The IPM does not react to any switch inputs.

The IPM does not react to any switch inputs of equal or lower priority. If 2 switches are closed at the same time the IPM will read the least resistive path, so that switch takes precedence over the other one.

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.

The following are the correct resistance value ranges and counts displayed by IPM. The counts displayed by the scan tool proportionally vary with battery voltage.

DTC B3622

DTC B3622

Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. Each module on GMLAN network maintains 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 a DTC U0001 will be set.

This diagnostic procedure supports the following DTC

DTC U0001 High Speed CAN Communication Bus

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to Symptoms - Vehicle in Vehicle DTC Information.

DTC U0001

Conditions for Running the DTCs

1. Voltage supplied to the module is in the normal operating voltage range.
2. The vehicle power mode requires serial data communication to occur.

A certain number of no valid transmitted messages on the GMLAN serial data circuits are detected by the module.

Action Taken When the DTCs Sets

1. The module suspends all message transmission.
2. The module uses default values for all parameters received on the GMLAN serial data circuits.
3. The module inhibits the setting of all other GMLAN 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, without a repeat of the malfunction.

1. This DTC cannot be retrieved with a current status. Diagnosis of current DTC is accomplished via the symptom, Scan Tool Does Not Communicate with GMLAN Device. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with) .
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 GMLAN Device procedure in order to isolate an intermittent condition. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with) .

Modules connected to the high 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. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.

This diagnostic procedure supports the following DTC

DTC U0002 Fewer Controllers On than Programmed

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC U0002

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 U0001 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. A poor connection at the inoperative module may cause this code to set.
2. An improperly powered module may cause this code to set.

DTC U0002

Modules connected to the high 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. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC U0100 Lost Communication With Engine Control Module (ECM)
2. DTC U0101 Lost Communication With Transmission Control Module (TCM)
3. DTC U0104 Lost Communication With Distance Sensing and Cruise Control (DSCC) Module
4. DTC U0121 Lost Communication With Electronic Brake Control Module (EBCM)
5. DTC U0141 Lost Communication With Instrument Panel Module (IPM)
6. DTC U0181 Lost Communication With Dynamic Headlamp Leveling (DHL) Control Module

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC U0100-U0299

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 U0001 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. A poor connection at the inoperative module may cause this code to set.
2. An improperly powered module may cause this code to set.

DTC U0100-U0299

Modules connected to the GMLAN serial data circuit monitor for serial data communications on the GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. Each module on GMLAN network maintains 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 a DTC U2100 will be set.

This diagnostic procedure supports the following DTC

DTC U2100 Controller Area Network (CAN) Bus Communication

This vehicle has DTCs which include DTC Symptoms. The DTC symptom descriptions for symptoms 71 and 72 are exceptions for this vehicle and differ from what is described on DTC Symptom Description. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC U2100

1. Voltage supplied to the module is in the normal operating voltage range.
2. The vehicle power mode requires serial data communication to occur.

A certain number of no valid transmitted messages on the GMLAN serial data circuits are detected by the module.

1. The module suspends all message transmission.
2. The module uses default values for all parameters received on the GMLAN serial data circuits.
3. The module inhibits the setting of all other GMLAN communication DTCs for the respective bus.

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.

U2100 72

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. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with) .
2. An intermittent condition is likely to be caused by a short on the high speed high speed GMLAN serial data circuits. Use the Scan Tool Does Not Communicate with High Speed GMLAN Device procedure in order to isolate an intermittent condition. Refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with) .

U2100 71 and U2100 00

These DTCs can be retrieved from instrument panel module (IPM) with a current status. Refer to the table below to diagnose it. DTC U2100 00 can be retrieved with a current status only it was set for low speed GMLAN link. If set for high speed GMLAN link, see U2100 72.

The numbers below refer to the step numbers on the diagnostic table.

1. 4: The low speed serial data circuit is shorted to voltage or ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When testing the wire for a short, make sure there is not a module connected to the wire being tested. This test isolates the splice pack SP303 serial data circuits.
2. 7: The low speed serial data circuit is shorted to voltage or ground. The condition may be due to the wiring or due to a malfunction in one of the modules. When testing the wire for a short, make sure there is not a module connected to the wire being tested. This test isolates the splice pack SP300 serial data circuits.
3. 10: This test isolates the splice pack SP201 serial data circuits.
4. 15: If there are no current DTCs that begin with a "U", the communication malfunction has been repaired.
5. 16: The communication malfunction may have prevented diagnosis of the customer complaint.

DTC U2100

Modules connected to the high 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. The supervision time-out period is 250 milliseconds. Each message contains the identification number of the transmitter module.

This diagnostic procedure supports the following DTC

DTC U2103 Fewer Controllers On than Programmed

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC U2103

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. A poor connection at the inoperative module may cause this code to set.
2. An improperly powered module may cause this code to set.

DTC U2103

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.

This diagnostic procedure supports the following DTCs

1. DTC U2105 Lost Communication With Engine Control Module (ECM)
2. DTC U2106 Lost Communication With Transmission Control Module (TCM)
3. DTC U2108 Lost Communication With Electronic Brake Control Module (EBCM)
4. DTC U2112 Lost Communication With Electronic Suspension Control (ESC)
5. DTC U2113 Lost Communication With Sensing and Diagnostic Module (SDM)
6. DTC U2116 Lost Communication With Instrument Panel Cluster (IPC)
7. DTC U2118 Lost Communication With Head Up Display (HUD)
8. DTC U2120 Lost Communication With Dynamic Headlamp Leveling (DHL) Device
9. DTC U2122 Lost Communication With Radio
10. DTC U2124 Lost Communication With Audio Amplifier
11. DTC U2125 Lost Communication With Communication Interface Module (OnStar)
12. DTC U2127 Lost Communication With HVAC
13. DTC U2130 Lost Communication With Driver Door Module (DDM)
14. DTC U2132 Lost Communication With Passenger Door Module (PDM)
15. DTC U2135 Lost Communication With Rear Integration Module (RIM)
16. DTC U2138 Lost Communication With Steering Column Lock Control Module (SCLCM)
17. DTC U2144 Lost Communication With Distance Sensing Cruise Control (DSCC) Module
18. DTC U2162 Lost Communication With Instrument Panel integration Module (IPM)
19. DTC U2163 Lost Communication With Left Rear Door Module (LRDM)
20. DTC U2164 Lost Communication With Right Rear Door Module (RRDM)
21. DTC U2165 Lost Communication With Driver Door Switch (DDS)
22. DTC U2166 Lost Communication With Driver Position Module (DPM)
23. DTC U2167 Lost Communication With Remote Control Door Lock Receiver (RCDLR)
24. DTC U2172 Lost Communication With Digital Radio Receiver (DRR)
25. DTC U2179 Lost Communication With Television Module

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC U2105-U2199

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. A poor connection at the inoperative module may cause this code to set.
2. An improperly powered module may cause this code to set.

DTC U2105-U2199

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2004-2007/remont/oem-general-information/#vehicle-dtc-information) in Vehicle DTC Information 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/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems) «Body Control System Description and Operation»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__body-control-system-description-and-operation) «Retained Accessory Power (RAP) Description and Operation»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems)

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the systems. Refer to «Checking Aftermarket Accessories»(/cadillac/sts/i-2004-2007/remont/body-electrical/#wiring-systems-electrical-power-management-introduction__checking-aftermarket-accessories) in Wiring Systems.
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 in Wiring Systems.

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/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems)
2. «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__scan-tool-does-not-communicate-with)
3. «Scan Tool Does Not Communicate with Low Speed GMLAN Device»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems)
4. «Retained Accessory Power (RAP) On After Timeout»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__retained-accessory-power-rap-on-after)
5. «Retained Accessory Power (RAP) Inoperative»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__retained-accessory-power-rap-inoperative)

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 power battery positive voltage at terminal 16
2. Scan tool power ground at terminal 4
3. Common signal ground at terminal 5

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.

The number below refers to the step number on the diagnostic table.

1. 4: If the battery positive voltage and ground circuits of the DLC are functioning properly, the malfunction must be due to the scan tool.

Scan Tool Does Not Power Up

Scan Tool Does Not Communicate with High Speed GMLAN Device

Modules connected to the high speed GMLAN serial data circuits monitor for serial data communications on the high speed GMLAN network during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module detects a bus-off condition a DTC U0001 or U2100 will be set. These DTCs can be retrieved as history only.

The high speed GMLAN serial data bus uses two 120 ohms terminating resistors that are in parallel with the high speed GMLAN (+) and (-) circuits. One of the resistors is connected at the instrument panel module (IPM) and the other is at the engine control module (ECM). When testing for a short between high speed GMLAN (+) and (-) a reading of 60 ohms is normal. If the high speed GMLAN serial data is open testing the resistance between high speed GMLAN (+) and (-) will read about 120 ohms.

The engine will not start when there is a total malfunction of the high speed GMLAN serial data circuits while the engine is not running. The following conditions may cause a total loss of high speed GMLAN data communication

1. A short between high speed GMLAN (+) and high speed GMLAN (-) circuits
2. Any of the high speed GMLAN serial data circuits shorted to ground or voltage
3. A module internal malfunction that causes a short to voltage or ground on the high speed GMLAN circuits
4. Any of the high speed GMLAN serial data circuits open

The numbers below refer to the step numbers on the diagnostic table.

1. 2: A partial malfunction in the high speed GMLAN serial data circuits uses a different procedure from a total malfunction of the high speed GMLAN data circuits. The scan tool communicates with the following modules on the high speed GMLAN serial data circuits: Distance sensing cruise control (DSCC) module Instrument panel module (IPM) Electronic brake control module (EBCM) Electronic suspension control (ESC) module Engine control module (ECM) Transmission control module (TCM)
2. 8: Data link connector (DLC) terminals 6 and 14 provide the connection to the GMLAN serial data high circuit and the GMLAN serial data low circuit respectively.
3. 15: If only one of the high speed GMLAN circuits is open all communication on the high speed bus will be disrupted.
4. 19: The communication malfunction may have prevented diagnosis of the customer complaint.

Scan Tool Does Not Communicate with High Speed GMLAN Device

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. Connecting a scan tool to the data link connector (DLC) allows communication with the modules for diagnostic purposes.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: A current DTC U2100 71 or U2100 00 may be retrieved only from instrument panel module (IPM).
2. 4: A partial malfunction in the low speed GMLAN serial data circuit uses a different procedure from a total malfunction of the low speed GMLAN serial data circuit. The scan tool communicates with the following modules on the low speed GMLAN serial data circuit: Audio amplifier Communication interface module (OnStar) Digital radio receiver (DRR) Driver door module (DDM) Driver door switch (DDS) Driver position module (DPM) Head up display (HUD) HVAC control module Inflatable restraint sensing and diagnostic module (SDM) Instrument panel cluster (IPC) Left rear door module (LRDM) Passenger door module (PDM) Radio Rear integration module (RIM) Remote control door lock receiver (RCDLR) Right rear door module (RRDM) Steering column lock control module (SCLCM) Television module
3. 10: An open in the low speed GMLAN serial data circuit between the DLC and instrument panel module (IPM) will prevent the scan tool from communicating with any module on the low speed GMLAN bus. This condition will not set a DTC.

Scan Tool Does Not Communicate with Low Speed GMLAN Device

Retained Accessory Power (RAP) On After Timeout

Retained Accessory Power (RAP) On After Timeout

Retained Accessory Power (RAP) Inoperative

Retained Accessory Power (RAP) Inoperative

Control Module References

Control Module References

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 .

Data Link References

Removal Procedure

1. Remove the instrument panel compartment. Refer to «Compartment Replacement - Instrument Panel (I/P)»(/cadillac/sts/i-2004-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages, and Console.
2. Remove the screws securing the dash integration module to the module bracket.
3. Disconnect the electrical connectors.

Installation Procedure

1. Connect the electrical connectors.
2. Install the module to the bracket.
3. Install the screws that secure the module to the bracket. Tighten: Tighten the screws to 2 N.m (18 lb in).
4. Install the instrument panel compartment. Refer to «Compartment Replacement - Instrument Panel (I/P)»(/cadillac/sts/i-2004-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages, and Console.
5. Reprogram the module. Refer to «Control Module References»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__control-module-references) .

1. Remove the rear upper compartment trim. Refer to «Compartment Trim Panel Replacement - Rear»(/cadillac/sts/i-2004-2007/remont/exterior-body-panels/#body-rear-end) in Body Rear End.
2. Release the tabs securing the rear integration module (2) to the module bracket.
3. Disconnect the electrical connectors.

1. Connect the electrical connectors.
2. Install the module (2) to the bracket.
3. Install the rear upper compartment trim. Refer to «Compartment Trim Panel Replacement - Rear»(/cadillac/sts/i-2004-2007/remont/exterior-body-panels/#body-rear-end) in Body Rear End.
4. Reprogram the module. Refer to «Control Module References»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems__control-module-references) .

1. Remove the knee bolster trim. Refer to «Knee Bolster Replacement»(/cadillac/sts/i-2004-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages, and Console.
2. Remove the screws (1) securing the data link connector to the instrument panel (I/P).

1. Locate the connector to the I/P.
2. Install the screws (1) securing the connector to the I/P. Tighten: Tighten the screws (1) to 2 N.m (18 lb in).
3. Install the knee bolster trim. Refer to «Knee Bolster Replacement»(/cadillac/sts/i-2004-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages, and Console.

General Information to Setup the Instrument Panel Module (IPM)

Before performing any of the setup procedures ensure the following

1. The scan tool has been updated with the latest software version.
2. The battery is fully charged.
3. All modules on the serial data line are connected.

The following procedures must be performed when a new IPM is installed

1. Setup New IPM/RIM
2. Program vehicle identification number (VIN)
3. Brake Pedal Position (BPP) Sensor Calibration

Setup New IPM/RIM

This procedure will allow the user to compare the IPM and rear integration module (RIM) vehicle configuration data. The IPM is the master for storing vehicle configuration and a backup copy is retained in the RIM. If a fault occurs in either module, this test will do a comparison of data and the user will then be able to update the data in the module that was replaced.

To set up a new IPM, perform 'Setup New IPM/RIM' procedure under Vehicle Control Systems > Computer/Integrating Systems > Module Setup > IPM menus on the scan tool.

Excepting the Export Country option, which is slightly different, the screen will display 4 columns. The user will be able to scroll up and down with the up and down arrow keys in all columns. The user will be able to scroll through options available to that name/function in the fourth column with the left and right arrow keys. The first column will display the function of the option. The second column will display RIM data and the third column will display IPM data. The forth and final column will display all options available for that name/function. The user will compare the RIM to the IPM data or the IPM to the RIM data depending on which module was replaced. If the user replaces the IPM, the user will scroll through the options with the left and right arrow keys in the fourth column and match that option with the option set in the RIM column. Likewise, if the user replaces the RIM, the user will scroll through the options with the left and right arrow keys in the fourth column and match that option with the option set in the IPM column.

The following options can be set up

1. Export Country
2. Engine Type
3. Aux. Heater/KA6
4. TVT/YQ6 or YQ7 - TV Tuner
5. DRR/U2K - Digital Radio Receiver
6. Remote Start
7. Theft Export/CU9
8. CTD Present - Content Theft Deterrent (UK)
9. Automatic Trans.
10. AWD/MV3 - ACC Wheel Drive
11. Alarm Export/UA2
12. ACC/K59 - Adaptive Cruise Control
13. Driver Position
14. MSM Lumbar/AL2 - Memory Seat Module
15. MSM/A45 - Memory Seat Module
16. Intru Export/UA2 - Intrusion Sensor
17. Heated Seats/KA1
18. Speed Biasing
19. HUD/UV6 - Head Up Display
20. Incli Exp/UA2 - Inclination Sensor
21. VCIM/UE1 - OnStar®
22. SCLM/UA2 - Steering Column Lock Module
23. RWD/M22 or M82 - Rear Wheel Drive
24. SOD/UEB - Side Object Detection
25. ESC/F55 - Electronic Suspension Control
26. Overspeed /Warn.
27. TCS - Traction Control System
28. TPM - Tire Pressure Monitoring
29. Smart Beam /TQ5
30. Headlamp Level
31. Air Quality /K14
32. HV Seat /KB6 - Heated/Vented Seat
33. Metric FE Units - Fuel Economy Units
34. DRL/Z49 - Daytime Running Lamps
35. HID/TT6/TT7/TT8 - High Intensity Discharge Lamps
36. Fog Lmps not Us /Can
37. SWC/K59 - Steering Wheel Control Switches with Adaptive Cruise Control
38. SWC/UE1 - with OnStar®
39. SWC Htd St WHL - with Heated Steering Wheel

After all options were set, save them using Save Options. If the option setting was successfully, Procedure Complete message will be displayed. The power mode will toggle from Run to Accessory.

Program VIN

This procedure needs to be performed if IPM is replaced. Under Module Setup > IPM menu, perform the program VIN procedure following the Tech 2 instructions.

BPP Sensor Calibration

This procedure needs to performed whenever IPM or BPP sensor was replaced. Refer to Brake Pedal Position Sensor Calibration in Lighting Systems.

1. Turn the ignition OFF for 10 seconds.
2. Connect the scan tool to the data link connector (DLC).
3. Turn the ignition ON, with the engine OFF.
4. Use the scan tool in order to retrieve history DTCs from all modules.
5. Clear all history DTCs.

General Information to Setup the Rear Integration Module (RIM)

Before performing any of the setup procedures ensure the following

1. The scan tool has been updated with the latest software version.
2. The battery is fully charged.
3. All modules on the serial data line are connected.

This procedure will allow the user to compare the IPM and rear integration module (RIM) vehicle configuration data. The IPM is the master for storing vehicle configuration and a backup copy is retained in the RIM. If a fault occurs in either module, this test will do a comparison of data and the user will then be able to update the data in the module that was replaced.

To set up a new IPM, perform 'Setup New IPM/RIM' procedure under Vehicle Control Systems > Computer/Integrating Systems > Module Setup > IPM menus on the scan tool.

Excepting the Export Country option, which is slightly different, the screen will display 4 columns. The user will be able to scroll up and down with the up and down arrow keys in all columns. The user will be able to scroll through options available to that name/function in the fourth column with the left and right arrow keys. The first column will display the function of the option. The second column will display RIM data and the third column will display IPM data. The forth and final column will display all options available for that name/function. The user will compare the RIM to the IPM data or the IPM to the RIM data depending on which module was replaced. If the user replaces the IPM, the user will scroll through the options with the left and right arrow keys in the fourth column and match that option with the option set in the RIM column. Likewise, if the user replaces the RIM, the user will scroll through the options with the left and right arrow keys in the fourth column and match that option with the option set in the IPM column.

The following options can be set up

1. Export Country
2. Engine Type
3. Aux. Heater/KA6
4. TVT/YQ6 or YQ7 - TV Tuner
5. DRR/U2K - Digital Radio Receiver
6. Remote Start
7. Theft Export/CU9
8. CTD Present - Content Theft Deterrent (UK)
9. Automatic Trans.
10. AWD/MV3 - ACC Wheel Drive
11. Alarm Export /UA2
12. ACC/K59 - Adaptive Cruise Control
13. Driver Position
14. MSM Lumbar/AL2 - Memory Seat Module
15. MSM/A45 - Memory Seat Module
16. Intru Export /UA2 - Intrusion Sensor
17. Heated Seats/KA1
18. Speed Biasing
19. HUD/UV6 - Head Up Display
20. Incli Exp /UA2 - Inclination Sensor
21. VCIM/UE1 - OnStar®
22. SCLM/UA2 - Steering Column Lock Module
23. RWD/M22 or M82 - Rear Wheel Drive
24. SOD/UEB - Side Object Detection
25. ESC/F55 - Electronic Suspension Control
26. Overspeed/Warn.
27. TCS - Traction Control System
28. TPM - Tire Pressure Monitoring
29. Smart Beam/TQ5
30. Headlamp Level
31. Air Quality/K14
32. HV Seat/KB6 - Heated/Vented Seat
33. Metric FE Units - Fuel Economy Units
34. DRL/Z49 - Daytime Running Lamps
35. HID/TT6/TT7/TT8 - High Intensity Discharge Lamps
36. Fog Lmps not Us/Can
37. SWC/K59 - Steering Wheel Control Switches with Adaptive Cruise Control
38. SWC/UE1 - with OnStar®
39. SWC Htd St WHL - with Heated Steering Wheel

After all options were set, save them using Save Options. If the option setting was successfully, Procedure Complete message will be displayed. The power mode will toggle from Run to Accessory.

1. Turn the ignition OFF for 10 seconds.
2. Connect the scan tool to the data link connector (DLC).
3. Turn the ignition ON, with the engine OFF.
4. Use the scan tool in order to retrieve history DTCs from all modules.
5. Clear all history DTCs.

The communication among modules is performed through the low speed and high speed GMLAN serial data circuits. The modules that need real time communication are attached to the high speed GMLAN network. The instrument panel module (IPM) is the gateway between the networks. The purpose of the gateway is to transfer information from one network to another. The gateway will interact with each network according to that network's transmission model. Refer to Body Control System Description and Operation for more information about the gateway.

GMLAN network management supports selective start up and is based on virtual networks. A virtual network is a collection of signals started in response to a vehicle event. The starting of a virtual network signifies that a particular aspect of the vehicles's functionality has been requested. A virtual network is supported by virtual devices which represents a collection of signals owned by a single physical device. So, any physical device can have one or more virtual devices. The signal supervision is the process of determining whether an expected signal is being received or not. Failsofting is the ability to substitute a signal with a default value or a default algorithm, in the absence of a valid signal. Some messages are also interpreted as a "heartbeat" of a virtual device. If such a signal is lost, the application will set a no communication code against the respective virtual device. This code is mapped on the Tech 2 screen as a code against the physical device. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.

High Speed GMLAN Circuit Description

The data link connector (DLC) allows a scan tool to communicate with the high speed GMLAN serial data circuit. The serial data is transmitted on 2 twisted wires that allow speed up to 500 Kbps. The twisted pair is terminated with two 120 ohms resistors, one is internal to the engine control module (ECM) and the other is internal to the instrument panel module (IPM). The resistors are used to reduce noise on the high speed GMLAN bus 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. The idle level which is approximately 2.5 volts is considered a recessive transmitted data and is interpreted as a logic 1. Driving the lines to their extremes adds 1 volt to high speed GMLAN serial data bus (+) and subtracts 1 volt from high speed GMLAN serial data bus (-) wire. This dominant state is interpreted as a logic 0.

Two different outputs are used by IPM to activate the high speed GMLAN bus

1. Accessory wake up, active in all power modes when IPM is awake except Crank and in a remote start request
2. High speed communication enable, active in all power modes when IPM is awake and in a remote start request

The accessory wake up signal wakes up the ECM and the transmission control module (TCM) only. This output is disabled in Crank power mode for internal fail enable of the ECM and TCM. The high speed communication enable signal wakes up all the other modules on the high speed GMLAN bus.

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. The transmission speed for GMLAN low speed is up to 83.33 Kbps. This high speed is used for programming purposes only. Under normal vehicle operating conditions the speed of the bus is 33.33 Kbps. This protocol produces a simple pulse train sent out over the low speed GMLAN serial data bus. To wake up the control modules connected to the low speed GMLAN serial data bus, a wake-up pulse of 10 volts is sent out over the bus.

Data Link Connector (DLC)

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 power battery positive voltage at terminal 16
2. Scan tool power ground at terminal 4
3. Common signal ground at terminal 5
4. Low speed GMLAN serial data bus at terminal 1
5. High speed GMLAN serial data bus (+) at terminal 6
6. High speed GMLAN serial data bus (-) at terminal 14

High Speed GMLAN Serial Data Line

The GMLAN serial data communications circuit on this vehicle is in a linear topology. The following modules are connected to the link, in order from data link connector (DLC) to the end of the linear configuration

1. The instrument panel module (IPM)
2. The electronic suspension control (ESC) module, with F85
3. The communication interface module (OnStar), with UE1
4. The dynamic headlamp leveling (DHL) device, with TR7
5. The electronic brake control module (EBCM)
6. The transmission control module (TCM)
7. The engine control module (ECM)

The distance sensing and cruise control (DSCC) module, with K59 option, it is connected to the high speed GMLAN bus through splice pack SP100. Refer to Data Link Connector (DLC) Schematics for more information.

The OnStar module doesn't functionally communicate on the high speed GMLAN bus. It is connected to high speed GMLAN bus for remotely diagnostic purposes.

Low Speed GMLAN Serial Data Line

The low speed GMLAN serial data communication circuit on this vehicle is in a star configuration. The star has 3 splice packs, located as follows

1. The splice pack SP201 is located under the left side of the instrument panel (I/P), near the data link connector (DLC).
2. The splice pack SP300 is located next by the left B-pillar.
3. The splice pack SP303 is located next by the right B-pillar.

The following modules communicate on the low speed GMLAN serial data circuit

1. The splice pack SP201 attaches to: The instrument panel module (IPM) The head-up display (HUD), with UV6 The HVAC control module The instrument panel cluster (IPC) The radio The steering column lock control module (SCLCM), with UA2
2. The splice pack SP300 attaches to: The audio amplifier The driver door module (DDM) The driver door switch (DDS) is attached to DDM The driver position module (DPM), with A45 The digital radio receiver (DRR), with U2K The inflatable restraint sensing and diagnostic module (SDM) The left rear door module (LRDM) The rear integration module (RIM) The remote control lock door receiver (RCDLR) The television (TV) module, with YK6/YK7
3. The splice pack SP303 attaches to: The communication interface module (OnStar), with UE1 The inflatable restraint SDM The passenger door module (PDM) The right rear door module (RRDM)

Refer to Data Link Connector (DLC) Schematics for more information.

Body Control System Description and Operation

The body control system consists of the following 2 modules

1. The instrument panel module (IPM)
2. The rear integration module (RIM)

IPM Overview

The main features of the instrument panel module (IPM) are

1. The IPM is the gateway between low speed and high speed GMLAN serial data circuits.
2. The IPM is the power mode master.
3. The IPM controls electrical power management.
4. The IPM controls multiple functions.

Gateway

The instrument panel module (IPM) is the gateway between low speed and high speed GMLAN serial data circuits. The purpose of the gateway is to transfer serial data messages from one subnet to another. The IPM shall unpack the signals from frames received from one bus that are to be transmitted across the gateway and repack the signals into frames to be transmitted on the other bus. The IPM shall be responsible for data passing only. The data passed from one bus to the other shall in no way be modified by the IPM gateway function. The IPM receives 3 distinct types of messages on a given bus

1. Signals the IPM uses for internal functional applications
2. Signals the IPM uses for internal functional applications and are passed from one bus to the other bus
3. Signals the IPM does not use for internal functional applications but are passed from one bus to the other bus

Power Mode

The IPM is the power mode master (PMM). Refer to Power Mode Description and Operation for more information.

Load Management

The power management function is designed to monitor the vehicle electrical load and determine when the battery is potentially in a high discharge condition. This is accomplished by using a high accuracy battery voltage and current reading by a current sensor as an indicator of battery discharge rate. The following 6 levels of load management will execute in the load management control algorithm when there is a high discharge condition

1. The first action requests a vehicle idle speed increase to the engine control module (ECM) in order to raise alternator output.
2. The second action requests a greater vehicle idle speed increase to the ECM in order to raise alternator output.
3. The third action begins to shed vehicle loads in an attempt to remedy the heavy discharge condition.
4. The fourth action requests another vehicle idle speed increase to the ECM in order to raise further the alternator output.
5. The fifth action begins to shed further vehicle loads in an attempt to remedy the heavy discharge condition.
6. If the above 5 corrective actions fail, the sixth action of power management further sheds loads in a final attempt to remedy the high discharge condition.

Loads subject to reduction include the following

1. The A/C clutch
2. The heated mirrors
3. The heated seats
4. The rear defog
5. The HVAC blowers
6. The interior lighting

For more information about load shedding, refer to Load Shed System Description and Operation in Engine Electrical.

Each load management function, either idle boost or load-shed, is discrete. No 2 functions are implemented at the same time. During each load management function, the power mode master (PMM) checks the battery temperature, battery voltage and amp-hour calculations and determines if the PMM should implement a different power management function.

Regulator Voltage Control (RVC)

Regulator voltage control (RVC) will result in the battery being charged at its optimum voltage for improved battery life and state of charge (SOC), fuel economy and lamp life by lowering the system voltage when the SOC is high. The electrical power management (EPM) algorithm in the instrument panel module (IPM) will determine the optimum charging voltage, based on estimates of its SOC and battery electrolyte temperature. Optimum charge voltage is defined as the battery charge voltage that results in maximum battery life, while maintaining energy storage for engine starting, discharge at idle, and parasitic loads. The optimum battery charge voltage will be converted to a percent duty cycle command that will be sent to the ECM via serial data link. The ECM will then place the 128 Hz pulse width modulation (PWM) duty cycle on the L line.

Other IPM Functions

The instrument panel module (IPM) performs multiple body control functions. The IPM can control devices directly connected to its outputs based on input information. The IPM evaluates this information and controls certain body control systems by commanding outputs on or off. The IPM inputs can be

1. Sensors and switches that are directly connected to the IPM
2. GMLAN serial data messages received from other vehicles systems connected to the low or high speed GMLAN serial data links

The IPM is also capable of controlling other vehicle systems that are not directly wired to the IPM, through serial data messages. Some of the functions that the IPM controls or contributes to, are

1. Audible warnings - Refer to «Indicator/Warning Message Description and Operation»(/cadillac/sts/i-2004-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console__indicatorwarning-message-description-and-operation) in Instrument Panel, Gages, and Console.
2. Column lock - Refer to «Steering Wheel and Column Description and Operation»(/cadillac/sts/i-2004-2007/remont/steering-column-switches/#steering-wheel-steering-column) in Steering Wheel and Column.
3. Exterior lighting control and BASS - Refer to «Exterior Lighting Systems Description and Operation»(/cadillac/sts/i-2004-2007/remont/exterior-lights/#lighting-systems-introduction) in Lighting Systems.
4. Interior lighting - Refer to «Interior Lighting Systems Description and Operation»(/cadillac/sts/i-2004-2007/remont/exterior-lights/#lighting-systems-introduction) in Lighting Systems.
5. Headlamp washer - Refer to «Headlamp Washer System Description and Operation»(/cadillac/sts/i-2004-2007/remont/wiperwasher-systems/#wiper-system-and-washer-system) in Wipers/Washer Systems.
6. Horn control - Refer to «Horns System Description and Operation»(/cadillac/sts/i-2004-2007/remont/horns/#horn-system) in Horns.
7. Park brake switch - Refer to «Park Brake System Description and Operation»(/cadillac/sts/i-2004-2007/remont/parking-brake-system/#parking-brake-system) in Park Brake.
8. Personalization - Refer to «Personalization Description and Operation»(/cadillac/sts/i-2004-2007/remont/memory-modules/#personalization-systems) in Personalization.
9. Retained accessory power - Refer to «Retained Accessory Power (RAP) Description and Operation»(/cadillac/sts/i-2004-2007/remont/communication-devices/#computerintegrating-systems) .
10. Remote start - Refer to «Starting System Description and Operation»(/cadillac/sts/i-2004-2007/remont/charging-system/#battery-charging-system-and-starting-system__starting-system-description-and-operation) in Engine Electrical.
11. Steering wheel control switches - Refer to «Radio/Audio System Description and Operation»(/cadillac/sts/i-2004-2007/remont/entertainment-systems/#entertainment-system__radioaudio-system-description-and-operation) in Entertainment and «Cruise Control Description and Operation (Adaptive Cruise Control)»(/cadillac/sts/i-2004-2007/remont/cruise-control-systems/#cruise-control-system) or «Cruise Control Description and Operation (Conventional Cruise Control)»(/cadillac/sts/i-2004-2007/remont/cruise-control-systems/#cruise-control-system__cruise-control-description-and-operation-conventional) in Cruise Control.
12. Traction control switch - Refer to «ABS Description and Operation»(/cadillac/sts/i-2004-2007/remont/anti-locktraction-control/#antilock-brake-system-traction-control-system-stability-control-system) in Antilock Brake System.

Rear Integration Module (RIM)

The various rear integration module (RIM) inputs and outputs are described in the corresponding functional areas as indicated on the RIM electrical schematics. The RIM functions include the following

1. Content theft deterrent - Refer to «Content Theft Deterrent (CTD) Description and Operation»(/cadillac/sts/i-2004-2007/remont/door-locks-anti-theft-systems/#theft-deterrent-system__content-theft-deterrent-ctd-description-and) in Theft Deterrent.
2. Interior lighting - Refer to «Interior Lighting Systems Description and Operation»(/cadillac/sts/i-2004-2007/remont/exterior-lights/#lighting-systems-introduction) in Lighting Systems.
3. Exterior lighting - Refer to «Exterior Lighting Systems Description and Operation»(/cadillac/sts/i-2004-2007/remont/exterior-lights/#lighting-systems-introduction) in Lighting Systems.
4. Theft deterrent - Refer to «Content Theft Deterrent (CTD) Description and Operation»(/cadillac/sts/i-2004-2007/remont/door-locks-anti-theft-systems/#theft-deterrent-system__content-theft-deterrent-ctd-description-and) in Theft Deterrent.
5. Rear defogger - Refer to «Rear Window Defogger Description and Operation»(/cadillac/sts/i-2004-2007/remont/heated-glassdefoggers/#stationary-windows) in Stationary Windows.
6. Rear park assist chime control - Refer to «Object Detection Description and Operation»(/cadillac/sts/i-2004-2007/remont/collisionavoidance/#rear-parking-assist-system__object-detection-description-and-operation) in Rear Parking Assist.
7. Sunroof control - Refer to «Sunroof Description and Operation»(/cadillac/sts/i-2004-2007/remont/sun-rooft-topconvertible-top/#sunroof-system) in Roof.

On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle the PMM is the instrument panel module (IPM). The IPM will monitor the ignition mode switch only with battery voltage above 7 volts to prevent invalid input readings during low voltages encountered during vehicle cranking. If the ignition mode switch input or the battery voltage input changes, a ratiometric calculation of ignition mode switch input value is performed. The IPM discerns the following states over the ignition mode switch signal circuits

1. Switch inactive
2. Switch stuck
3. Start button active
4. Off/Acc button active
5. Ignition mode switch signal circuit short to ground
6. Ignition mode switch signal circuit short to B+

To determine the correct power mode the IPM uses

1. The ignition mode switch data received from the ignition mode switch
2. The status of the engine run flag (ERF)

The following power modes are transmitted on both low speed and high speed GMLAN serial data circuits

1. Off-Awake
2. Accessory
3. Run
4. Crank

The accessory power mode times out after 20 minutes and the power mode becomes Off-Awake.

The following outputs are controlled by IPM as part of the power moding task

1. Accessory voltage, active in Accessory and Run power modes.
2. Run Ignition 3 voltage, active in a remote start request and in Run power mode.
3. Run/Crank Ignition 1 voltage, active in a remote start request and in Run and Crank power modes.
4. Engine control module (ECM)/transmission control module (TCM) serial data wake-up, active in a remote start request and in all power modes when IPM is awake except Crank.
5. High speed GMLAN serial data wake up, active in a remote start request and in all power modes when IPM is awake.

Fail-safe Operation

The remote control door lock receiver (RCDLR) is the backup power mode master (BPMM). The both IPM and RCDLR receive signals from the ignition mode switch, representing the mode switch data, through 2 different circuits. The RCDLR can determine and transmit all the system power modes per the lists above. Since the operation of the vehicle systems depends on the power mode, there is a fail-safe plan in place if the power mode message is not received from the IPM or RCDLR. The fail-safe plan covers modules with discrete ignition signal inputs as well as those modules using exclusively serial data control of power mode. The ECM and TCM behave differently.

Serial Data Messages

If no power mode message can be received, the modules remain in the last power mode received and check for the ERF message. If the ERF serial data is true, indicating that the engine is running, the modules fail-safe to Run power mode. In this state the modules and their subsystems can support all operator requirements. If the engine run flag serial data is false, indicating that the engine is not running, the modules fail-safe to Off-Awake power mode and shut down after a while if no other conditions require them to be awake.

Discrete Power Mode Signals

Those modules that have Run/Crank signal inputs also remain in the state dictated by the last valid power mode message from the IPM or the RCDLR. They then check the state of their Run/Crank Ignition 1 voltage input to determine the current valid state. If the discrete ignition input is active, the modules will fail-safe to the Run power mode. If the discrete ignition input is inactive, the modules will fail-safe to Off-Awake power mode and shut down after a while if no other conditions require them to be awake.

ECM and TCM Power Mode Backup Strategy

The ECM and TCM remain in the last known power mode state until it can determine its backup system power mode based on their discrete Accessory voltage and Run/Crank Ignition 1 voltage inputs.

Power Mode Description and Operation

Serial Data Control of Retained Accessory Power (RAP)

Retained accessory power (RAP) permits the operation of some devices after the ignition switch is turned OFF. These selected items will remain in operation until any of the front passenger doors is opened or until the RAP function timer reaches its shut-off limit, which is 10 minutes. The instrument panel module (IPM) monitors the ignition mode signal from the ignition mode switch, battery condition and the front doors status to determine whether RAP should be initiated.

RAP will end when one of the following conditions is met

1. The IPM receives information about the opening of the driver or the front passenger door.
2. The RAP timer expires.
3. The battery capacity decreases below a prescribed limit.
4. Any other ignition switch state is chosen.

The functions supported in the RAP power mode are

1. The power windows
2. The instrument panel cluster (IPC) and driver information center (DIC) displays
3. The entertainment devices
4. The sunroof

The sunroof operation is allowed when sunroof enable signal circuit from rear integration module (RIM) to sunroof module is active. The circuit is activated by RIM anytime, in all power modes, except Off-Awake. In Off-Awake power mode, the sunroof enable signal circuit is activated by RIM for the RAP period.

See also:
• Diagnostic System Check - Vehicle
• DTC Symptom Description
• Power Distribution Schematics
• Master Electrical Component List
• Circuit Testing
• Wiring Repairs
• Testing for Intermittent Conditions and Poor Connections
• Ignition Switch Replacement
• Diagnostic Trouble Code (DTC) List - Vehicle
• Cruise Control Schematics
• Cruise Control Connector End Views
• SIR Caution
• Connector Repairs
• Steering Wheel Control Switch Assembly Replacement
• Checking Aftermarket Accessories
• Symptoms - Doors
• Power Sunroof Inoperative
• Radio/Audio System Schematics
• OnStar Schematics
• OnStar Reconfiguration (Gen 6.1)
• OnStar Reconfiguration (Gen 5)
• Digital Radio Receiver Setup
• Door Control Module Schematics
• ABS Schematics
• Electronic Brake Control Module Programming and Setup
• Suspension Controls Schematics
• Engine Controls Schematics
• Engine Controls Schematics
• Engine Control Module Programming and Setup (4.6L)
• Garage Door Opener Schematics
• Headlight Leveling Schematics
• Headlamp Leveling Module Replacement
• Driver Seat Schematics
• HVAC Schematics
• HVAC Control Module Programming and Setup
• SIR Schematics
• Inflatable Restraint Sensing and Diagnostic Module Programming and Setup
• Inside Rearview Mirror Schematics
• Memory Seat Calibration Procedure
• Rear Parking Assist Schematics
• Keyless Entry Schematics
• Remote Control Door Lock Receiver Programming and Setup
• Control Module Setup (SCLCM Setup)
• Sunroof Motor/Actuator Synchronization
• Automatic Transmission Controls Schematics
• Window Regulator Motor Replacement - Front Door
• Window Regulator Motor Replacement - Rear Door
• Window Motor Programming - Express Function
• Fastener Notice
• Compartment Trim Panel Replacement - Rear
• Load Shed System Description and Operation
• Indicator/Warning Message Description and Operation
• Headlamp Washer System Description and Operation
• Horns System Description and Operation
• Park Brake System Description and Operation
• Personalization Description and Operation
• Starting System Description and Operation
• Radio/Audio System Description and Operation
• Cruise Control Description and Operation (Conventional Cruise Control)
• Content Theft Deterrent (CTD) Description and Operation
• Object Detection Description and Operation
• Control Module References
• Computer/Integrating Systems Connector End Views
• Scan Tool Does Not Communicate with High Speed GMLAN Device
• Data Link References
• Body Control System Description and Operation
• Retained Accessory Power (RAP) On After Timeout
• Retained Accessory Power (RAP) Inoperative