Data Communication System Cadillac DTS I

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DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Data Communications

Begin the system diagnosis with Diagnostic System Check - Vehicle . 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.

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__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 50, 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.
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.

Circuit/System Verification

If this DTC is retrieved as a current DTC, replace the module that set the DTC.

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/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__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/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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

The only requirements are voltage and ground.

The module has detected that the VIN is not programmed.

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 the VIN information to the body control module (BCM).
2. Turn the ignition OFF, wait several seconds and then turn the ignition ON.
3. Retrieve DTCs from the BCM. DTC B1016 should change to a history DTC. If this DTC is retrieved as a current DTC, replace the module that set the DTC.

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__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/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__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.

Conditions for Running the DTCs

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.

Action Taken When the DTCs Sets

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, Scan Tool Does Not Communicate with Low Speed GMLAN Device .

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__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 modules are in the normal operating range.
2. The vehicle power mode requires serial data communications.

The module setting the DTC has attempted to establish communications on the serial data circuits more than 3 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. Refer to «Data Link References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system__data-link-references) to determine which serial data system is used for a specific 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/dts/i-2005-2011/remont/communication-devices/#data-communication-system) or «Scan Tool Does Not Communicate with Low Speed GMLAN Device»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system) .

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

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 body control module (BCM) activates the serial data communication enable and the accessory wakeup serial data circuits by applying voltage 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. To determine which modules are activated using the enable or wakeup circuits refer to Data Communication Schematics .

The system voltage is between 9-16 volts.

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

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. 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 data link connector (DLC).
3. Use «Data Link References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system__data-link-references) to determine if the module uses high or low speed GMLAN serial data communications.
4. Some modules may not have internal protection for specific voltage outputs and may open a battery positive voltage or ignition voltage source fuse. If a voltage input fuse is open and no short is found in that circuit, ensure that no module output voltage circuit is shorted to ground before replacing the module.
5. This diagnostic can be used for any module that should communicate with high or low speed GMLAN serial data providing the vehicle is equipped with the option that uses that module.

Reference Information

Schematic Reference

1. «Data Communication Schematics»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that following BCM DTCs are not present: U1814 U2099 B1428 B1370 B1380 B1440 B1441 If any listed DTC is present, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) to diagnose that DTC prior to this diagnostic.
2. Verify that at least 1 module that communicates on high speed GMLAN serial data communicates with the scan tool. If no module communicates on high speed GMLAN serial data, refer to «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system) .
3. Verify that at least 1 module, excluding BCM, that communicates on low speed GMLAN serial data communicates with the scan tool. If no module communicates on low speed GMLAN serial data, excluding BCM, refer to «Scan Tool Does Not Communicate with Low Speed GMLAN Device»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system) .

Circuit/System Testing

1. Using the DTC Descriptor and Diagnostic Aids above, determine the module that is not communicating.
2. Ignition OFF, disconnect the necessary harness connector of the module that is not communicating.
3. Test for less than 1 ohm between the module ground circuits and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
4. Ignition ON, verify that a test lamp illuminates between the serial data communication enable circuit OR the accessory wakeup serial data circuit 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.
5. Ignition ON, verify that a test lamp illuminates between all battery positive voltage circuits 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 fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, replace the module.
6. Verify that a test lamp illuminates between all ignition voltage circuits 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 fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, replace the module.
7. Test for less than 1 ohm on the GMLAN serial data circuits between the non-communicating module and the module that displays the DTC. If greater than the specified range, test the serial data circuit for open/high resistance.
8. If all circuits test normal, replace the module that is not communicating.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «GMLAN Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis)
2. «Control Module References»(/cadillac/dts/i-2005-2011/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/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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. The DDM LIN bus is connected to all window regulator motors on its side of the vehicle, while the FPDM LIN bus is connected to the other window regulator motors. Communication on this network is only between the door modules and the window regulator motors. The window regulator motors are in effect modules. The window regulator motors do not communicate on any other data bus, therefore the door modules, which also communicate on the low speed GMLAN serial data bus will perform all communication with each other. If the driver depresses any passenger side window switch on the driver window switch the DDM communicates the information to the FPDM for operation. These DTCs will set in the DDM for driver side concerns or the FPDM for passenger side concerns.

The system voltage is between 9-16 volts.

U1511

1. The local interconnect network bus circuit of the front window motor has an open/high resistance.
2. The B+ circuit of the front window motor is open or shorted to ground.
3. The ground circuit of the front window motor is open.

U1512

1. The local interconnect network bus circuit of the rear window motor has an open/high resistance.
2. The B+ circuit of the rear window motor is open or shorted to ground.
3. The ground circuit of the rear window motor is open.

U1500 02

The local interconnect network bus circuit is a shorted to ground.

U1500 01

The local interconnect network bus circuit is a shorted to voltage.

U1511

The front window will operate.

U1512

The rear window will operate.

U1500

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

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. Both DTC U1511 and U1512 will set if an open/high resistance in the local interconnect network bus circuit is between the door module and the first splice.
2. Only 1 DTC (U1511 or U1512) will set if an open/high resistance in the local interconnect network bus circuit is between the splice and the window motor.

Schematic Reference

1. «Data Communication Schematics»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)
2. «Moveable Window Schematics»(/cadillac/dts/i-2005-2011/remont/heated-glassdefoggers/#fixed-moveable-window-systems)

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, disconnect the X2 harness connector at the appropriate window motor.
2. 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 1 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 5.5-7.0 volts between the LIN circuit terminal 6 and ground. If greater than the specified range, test the LIN circuit for a short to voltage. If the circuit tests normal, replace the applicable 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 applicable door module.
5. Ignition OFF, reconnect the harness connector at the window motor.
6. Ignition ON, observe the appropriate scan tool Front Window Motor Fault Status parameter while raising and lower the window. The parameter should read No Fault. If the parameter displays Not Normalized, refer to «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for programming the window motors. If the parameter reads Motor Fault, Hall Fault, Memory Fault, LIN Fault, Anti-Trap Fault or Thermo Active, test or replace the appropriate power window motor.
7. If all circuits test normal, replace the appropriate door module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for window, and door lock switch (door module) or window regulator motor replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The accessory wake up serial data circuit is a voltage wake up signal from the body control module (BCM) to the engine control module (ECM) and the transmission control module (TCM). The signal is activated in 2 ways; any time the ignition switch is in the ACC or RUN position, or anytime the 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.

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 modules is never signaled, therefore the specific subsystems 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.

1. Short to ground may open the fuse feeding the ignition switch.
2. Short to ground may also set multiple no communication codes for GMLAN high speed modules.

Schematic Reference

1. «Body Control System Schematics»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)
2. «Data Communication Schematics»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information.

1. Ignition OFF, disconnect the X1 harness connector at the ECM and the TCM one at a time. After each disconnect, test for current DTCs. DTC U1814 should remain current. If the DTC becomes history, replace the module disconnected when the DTC became history.
2. Ignition OFF, disconnect the X4 harness connector at the BCM.
3. Test for infinite resistance between the voltage circuit terminal 19 and ground. If less than the specified value, test the voltage circuit for a short to ground.
4. If all circuits 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/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using the diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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. Electronic brake control module (EBCM)
2. Electronic suspension control (ESC) module - (FE1) (F38) (F55)
3. Distance sensing cruise control (DSCC) module - (K59)

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/dts/i-2005-2011/remont/communication-devices/#data-communication-system)
2. «Data Communication Schematics»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information.

1. With the ignition OFF, disconnect the X 1 harness connector at the EBCM, DSCC, and ESC module one at a time. After each disconnect, retest for current DTCs. DTC U2099 should remain current. If the DTC becomes history, replace the module disconnected before the DTC became history.
2. Ignition OFF, disconnect the harness connector X 3 at the BCM.
3. With the X 1 harness connector at the EBCM, DSCC, and ESC modules 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.
4. 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

Symptoms - Data Communications

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) 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: «Body Control System Description and Operation»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system__body-control-system-description-operation) «Data Link Communications Description and Operation»(/cadillac/dts/i-2005-2011/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/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__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/dts/i-2005-2011/remont/communication-devices/#data-communication-system)
2. «Scan Tool Does Not Communicate with High Speed GMLAN Device»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)
3. «Scan Tool Does Not Communicate with Keyword Data Line»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)
4. «Scan Tool Does Not Communicate with Low Speed GMLAN Device»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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

Data Communication Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__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/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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 when the ignition switch is in any position other than OFF. The high speed GMLAN serial data circuits must be operational for the vehicle to start due to body control module (BCM) and engine control module (ECM) communications.

1. 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.
2. Use the «Data Link References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system__data-link-references) to identify the high speed GMLAN serial data modules.
3. This test is used for a total high speed GMLAN communication failure. If only one module is not communicating and sets no DTC, ensure that the vehicle is equipped with the module, then use DTC U0100-U0299 for diagnostics.
4. An open in the DLC ground circuit terminal 5 will allow the scan tool to operate and set up the vehicle on the tool and then not communicate with the vehicle. When the scan tool is to the point of communicating with the vehicle, a message on the scan tool will indicate "no CANdi module detected" and will not communicate.
5. The engine will not start when there is a total malfunction of the high speed GMLAN serial data bus. The following conditions may cause a total loss of high speed GMLAN data communication: A short between high speed GMLAN (+) and high speed GMLAN (-) circuits Any of the high speed GMLAN serial data circuits shorted to ground or voltage A module internal malfunction that causes a short to voltage or ground on the high speed GMLAN circuits

Schematic Reference

1. «Data Communication Schematics»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Test for less than 1.0 ohm between the ground circuit terminal 5 of the DLC and ground. If greater than the specified range, test the ground circuit for open/high resistance.
2. Remove the terminator resistor.
3. Test for 110-130 ohms between the terminals of the resistor. If not within the specified range, replace the resistor.
4. Connect the terminator resistor.
5. Ignition OFF, disconnect the harness connector X3 at the BCM.
6. Test for less than 2 ohms on the serial data circuit between terminal 6 of the DLC and terminal 16 of the BCM. If greater than the specified range, test the serial data circuit for open/high resistance.
7. Ignition OFF, disconnect the harness connector X4 of the BCM.
8. Verify a test lamp illuminates between each ground circuit terminal of the BCM listed below and B+. X3 terminal 1 X3 terminal 5 X4 terminal 9 If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
9. Ignition ON, verify a test lamp illuminates between each B+ circuit terminal of the BCM listed below and ground. X4 terminal 1 X4 terminal 3 X4 terminal 4 If the test lamp does not illuminate, test the B+ circuit for an open/high resistance or short to ground.
10. Ignition OFF, disconnect the harness connector of the EBCM.
11. Ignition ON, test for less than 1 volt between the serial data circuit terminal 6 of the DLC and ground, and terminal 14 of the DLC and ground. If greater than the specified range, test the serial data circuit for a short to voltage.
12. Test for infinite resistance between the serial data circuit terminal 6 of the DLC and ground, and terminal 14 of the DLC and ground. If less than the specified value, test the serial data circuit for a short to ground.
13. Test for infinite resistance between the serial data circuits terminal 6 and terminal 14 of the DLC. If less than the specified value, test the serial data circuits for a short between them.
14. Connect the harness connectors of the BCM and the EBCM.
15. Disconnect the harness connector X3 of the ECM.
16. Attempt to communicate with the suspension control module. Communication should not be available. If communication is available, replace the ECM.
17. Ignition OFF, disconnect the harness connector X1 of the TCM.
18. Attempt to communicate with the suspension control module. Communication should not be available. If communication is available, test the serial data circuits for a short between the circuits, short to voltage, or a short to ground between the TCM and the ECM. If the circuits test normal, replace the TCM.
19. Ignition OFF, disconnect the harness connector of the EBCM.
20. Attempt to communicate with the suspension control module. Communication should not be available. If communication is available, test the serial data circuits for a short between the circuits, short to voltage, or a short to ground between the EBCM and the TCM. If the circuits test normal, replace the EBCM.
21. Ignition OFF, connect the harness connectors of the EBCM, TCM, and ECM.
22. Ignition OFF, disconnect the harness connector X2 of the suspension control module.
23. Attempt to communicate with the EBCM. Communication should not be available. If communication is available, test the serial data circuits for a short between the circuits, short to voltage, or a short to ground between the suspension control module and the terminator resistor. If the circuits test normal, replace the suspension control module.
24. Ignition OFF, disconnect the harness connector of the distance sensing cruise control (DSCC) if equipped. Attempt to communicate with the EBCM. Communication should not be available. If communication is available, replace the DSCC module.
25. Ignition OFF, disconnect the harness connectors X1 and, X2 of the vehicle communication interface module (VCIM) if equipped. Attempt to communicate with the EBCM. Communication should not be available. If communication is available, test the serial data circuits for a short between the circuits, short to voltage, or a short to ground between the VCIM and the suspension control module. If the circuits test normal, replace the VCIM.
26. Ignition OFF, disconnect the harness connector X3 of the BCM.
27. Ignition ON, test for less than 1 volt between the serial data circuits of BCM terminal 8 and ground, and between BCM terminal 9 and ground. If greater than the specified range, test the circuit for a short to voltage.
28. Test for infinite resistance between the serial data circuits of BCM terminal 8 and ground, and between BCM terminal 9 and ground. If less than the specified value, test the circuit for a short to ground.
29. Test for infinite resistance between the serial data circuits terminal 8 terminal 9 of the BCM. If less than the specified VAlue, test the serial data circuits for a short between them.
30. If the circuits test normal, replace the BCM.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
2. «GMLAN Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using the diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The climate control seat module (CCSM) communicates with a scan tool via the keyword 2000 serial data circuit. The keyword 2000 system is for diagnostics of the CCSM only. There is no communication between any other modules on the keyword 2000 serial data system.

Some modules may not have internal protection for specific voltage outputs and may open a battery positive voltage or ignition voltage source fuse. If a voltage input fuse is open and no short is found in that circuit, ensure that no module output voltage circuit is shorted to ground before replacing the module.

Schematic Reference

1. «Heated/Cooled Seat Schematics»(/cadillac/dts/i-2005-2011/remont/seats/#seat-heating-system-seat-cooling-system)
2. «Data Communication Schematics»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, disconnect the harness connectors X1, X2, and X3 of the CCSM.
2. Test for less than 1 ohm of resistance between the module ground circuit terminal M X1 and ground. If greater than 1 ohm, repair the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between battery positive voltage circuit terminal E X1 and ground. If the test lamp does not illuminate, repair the battery positive voltage circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, replace the CCSM.
4. Ignition ON, verify that a test lamp illuminates between ignition voltage circuit terminal 1 X2 and ground. If the test lamp does not illuminate, repair the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, replace the CCSM.
5. Test for infinite resistance between the data link connector (DLC) keyword 2000 serial data circuit terminal 7 and ground. If less than the specified value, test the serial data circuit for a short to ground.
6. Test for less than 1 volt between the DLC keyword 2000 serial data circuit terminal 7 and ground. If greater than the specified range, test the serial data circuit for a short to voltage.
7. Test for less than 1 ohm of resistance in the keyword 2000 serial data circuit between the CCSM terminal 9 X3 and the DLC terminal 7. If greater than the specified range, test the serial data circuit for open/high resistance.
8. If all circuits test normal, replace CCSM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for CCSM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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 must be operational for the vehicle to start so the vehicle theft deterrent (VTD) module and body control module (BCM) can communicate. The low speed GMLAN serial data circuit uses JX 300 (splice pack comb) as a common connection between some modules and the DLC.

1. Use the «Data Link References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system__data-link-references) to identify the low speed GMLAN serial data modules.
2. This test is used for a total low speed GMLAN communication failure. If only 1 module is not communicating and sets no DTC, ensure that the vehicle is equipped with the module, then use «DTC U0100-U0299»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system) for diagnostics.
3. An open in the low speed GMLAN serial data circuit between the splice pack (comb) and a module(s) will only effect the specific module(s). This type of failure will set a loss of communication DTC for each module effected, and the other modules will still communicate.
4. An open in the DLC ground circuit terminal 5 will allow the scan tool to operate to set up the vehicle on the tool and then not communicate with the vehicle. When the scan tool is to the point of communicating with the vehicle, a message on the scan tool will indicate "no CANdi module detected" and will not communicate.
5. An open between the data link connector (DLC) and X 203 will only effect the communication with the scan tool. The vehicle modules will still communicate, and the vehicle will start.
6. The engine will not start when there is a total malfunction of the low speed GMLAN serial data circuit. The following conditions may cause a total loss of low speed GMLAN data communication: The low speed GMLAN serial data circuit shorted to ground or voltage. A module internal malfunction that causes a short to voltage or ground on the low speed GMLAN circuit. An open in the DLC ground circuit.

Schematic Reference

1. «Data Communication Schematics»(/cadillac/dts/i-2005-2011/remont/communication-devices/#data-communication-system)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references)

Connector End View Reference

1. «Component Connector End Views»(/cadillac/dts/i-2005-2011/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-component-connector-end-views)
2. «Splice Pack Connector End Views»(/cadillac/dts/i-2005-2011/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-starting-point-splice-pack-and-inline-harness-connector-end-views)

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information.

1. Test for less than 1.0 ohm between the DLC ground circuit terminal 5 and ground. If greater than the specified range, test the ground circuit for open/high resistance.
2. Ignition OFF, disconnect the harness connector (splice pack comb) at JX 300.
3. Ignition ON, with a scan tool, attempt to communicate with the instrument panel cluster (IPC). Communication should be available. If no communication, disconnect the modules still connected to the DLC one at a time, starting with the furthest from the DLC and attempt to communicate after each disconnect. When communication occurs, test the serial data circuit for a short to voltage and a short to ground between the last module disconnected and the previous module disconnected. If the circuit tests normal, replace the last module disconnected. If no communication is possible, test the serial data circuit for a short to ground, a short to voltage or an open/high resistance between the last module disconnected and the DLC. If the circuit tests normal, replace the last module disconnected.
4. Install a 3-amp fused jumper wire to JX 300 terminal L, harness side.
5. With IPC communications established, use the other end of the jumper wire to connect all other terminals, harness side, one at a time and verify that low speed communication remains available to the IPC. IMPORTANT: Allow communications for 5 seconds after connecting a module with the jumper to determine if communication is interrupted or not. If low speed communication is interrupted after connecting an individual module at JX 300, test the serial data circuit between JX 300 and the last module connected for a short to voltage and short to ground. If the circuit tests normal, replace the module that caused no communication.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for module replacement, setup, and programming
2. «GMLAN Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis)

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 .

Scheme 10

Body Control System Description & 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 GMLAN High speed serial data buss and the GMLAN Low speed serial data buss and acts as a gateway between them. If the BCM does not communicate the vehicle will not start due to the inability of the Engine/Powertrain Control Module (ECM/PCM) and Vehicle Theft Deterrent (VTD) Control Module to communicate without the BCM providing the gateway function.

Power Mode Master

This vehicles 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.

Serial Data Gateway

The BCM in this vehicle functions as a gateway or translator. The purpose of the gateway is to translate serial data messages between the GMLAN high speed buss and the GMLAN low speed buss 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/Powertrain Control Module (ECM/PCM) which is high speed serial data and Vehicle Theft Deterrent (VTD) Control Module which is low speed serial data. If these modules can not exchange information, the vehicle will not start.

Communication between the BCM and a scan tool can be on the high speed GMLAN network or low speed GMLAN network. If one network is lost, the BCM can still communicate with the scan tool. A lost communication DTC typically is set in modules other than the module with a communication failure.

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/dts/i-2005-2011/remont/anti-locktraction-control/#anti-lock-brake-system-traction-control-system-stability-control-system__abs-description-operation) .
2. Automatic day-night mirror-Refer to «Automatic Day-Night Mirror Description and Operation»(/cadillac/dts/i-2005-2011/remont/mirrors/#mirror-systems) .
3. Cruise control system-Refer to «Cruise Control Description and Operation (Conventional Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system__cruise-control-description-operation-conventional) or «Cruise Control Description and Operation (Adaptive Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) .
4. Electrical power management (EPM)-Refer to «Electrical Power Management Description and Operation»(/cadillac/dts/i-2005-2011/remont/charging-system/#battery-charging-system-and-starting-system) .
5. Exterior lighting-Refer to «Exterior Lighting Systems Description and Operation»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
6. Horn system -Refer to «Horns System Description and Operation»(/cadillac/dts/i-2005-2011/remont/horns/#horn-system) .
7. HVAC-Refer to «Air Delivery Description and Operation»(/cadillac/dts/i-2005-2011/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-operation) and «Air Temperature Description and Operation»(/cadillac/dts/i-2005-2011/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-operation) .
8. Instrument cluster indicator control-Refer to «Instrument Cluster Description and Operation»(/cadillac/dts/i-2005-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages) .
9. Interior lighting-Refer to «Interior Lighting Systems Description and Operation»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems) .
10. Power door lock system -Refer to «Power Door Locks Description and Operation»(/cadillac/dts/i-2005-2011/remont/door-locks-anti-theft-systems/#door-lock-systems-door-handles) .
11. Rear window defogger system -Refer to «Rear Window Defogger Description and Operation»(/cadillac/dts/i-2005-2011/remont/heated-glassdefoggers/#fixed-moveable-window-systems) .
12. Redundant steering wheel controls -Refer to «Steering Wheel Controls Description and Operation»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system__steering-wheel-controls-description-operation) .
13. Remote function actuation (RFA) control-Refer to «Keyless Entry System Description and Operation»(/cadillac/dts/i-2005-2011/remont/door-locks-anti-theft-systems/#keyless-entry-system-remote-functions__keyless-entry-system-description-operation) .
14. Retained accessory power (RAP)-Refer to «Retained Accessory Power (RAP) Description and Operation»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) .
15. Shift lock control system -Refer to «Automatic Transmission Shift Lock Control Description and Operation (Column Shift)»(/cadillac/dts/i-2005-2011/remont/automatic-trans/#shift-interlock-system__automatic-transmission-shift-lock-control-description) or «Automatic Transmission Shift Lock Control Description and Operation (Floor Shift)»(/cadillac/dts/i-2005-2011/remont/automatic-trans/#shift-interlock-system__automatic-transmission-shift-lock-control-description) .
16. Starting system-Refer to «Starting System Description and Operation»(/cadillac/dts/i-2005-2011/remont/charging-system/#battery-charging-system-and-starting-system__starting-system-description-operation) .
17. Supplemental inflatable restraint (SIR) system -Refer to «SIR System Description and Operation»(/cadillac/dts/i-2005-2011/remont/airbag/#supplemental-inflatable-restraint-system) .
18. Suspension system-Refer to «Electronic Suspension Control Description and Operation»(/cadillac/dts/i-2005-2011/remont/electronic-suspension/#suspension-control-system-suspension-damping) , and «Automatic Level Control Description and Operation (With F55)»(/cadillac/dts/i-2005-2011/remont/electronic-suspension/#suspension-control-system-automatic-level-control-alcm__automatic-level-control-description-operation) or «Automatic Level Control Description and Operation (W/O F55)»(/cadillac/dts/i-2005-2011/remont/electronic-suspension/#suspension-control-system-automatic-level-control-alcm__automatic-level-control-description-operation) .
19. Theft deterrent-Refer to «Immobilizer Description and Operation»(/cadillac/dts/i-2005-2011/remont/door-locks-anti-theft-systems/#immobilizer-system__immobilizer-description-operation) and «Content Theft Deterrent (CTD) Description and Operation»(/cadillac/dts/i-2005-2011/remont/door-locks-anti-theft-systems/#theft-deterrent-system__content-theft-deterrent-ctd-description) .
20. Wiper/Washer system functions-Refer to «Wiper/Washer System Description and Operation (Wiper and Washers)»(/cadillac/dts/i-2005-2011/remont/wiperwasher-systems/#wiper-system-washer-system) or «Wiper/Washer System Description and Operation (Heated Washer System)»(/cadillac/dts/i-2005-2011/remont/wiperwasher-systems/#wiper-system-washer-system__wiperwasher-system-description-and-operation-heated) .

Circuit Description

The communication among control modules is performed primarily through the GMLAN high speed serial data circuit and the GMLAN low speed serial data circuits. The modules that need real time communication are attached to the high speed GMLAN network. The body control module (BCM) is the serial data gateway between the networks. The purpose of the gateway is to translate serial data messages between the GMLAN high speed buss and the GMLAN low speed buss. The Local Interconnect Network (LIN) is another serial data communication network used on this vehicle which is dedicated to the door/power windows subsystem. Below are more detailed descriptions of the individual networks. The gateway will interact with each network according to that network's transmission protocol. Refer to Body Control System Description and Operation for more information about the gateway.

GMLAN High Speed 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 two twisted wires that allow speed 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 is after the vehicle communication interface module (VCIM). The VCIM is considered the DLC termination point of the link and the ECM is the other end of the link. The resistors are used to reduce noise on 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. 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 one volt to the high speed GMLAN serial data bus (+) and subtracts one volt from the high speed GMLAN serial data bus (-) wire. This dominant state is interpreted as a logic 0. 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 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: a loss of serial data DTC does not represent a failure of the module that the code is set in.

GMLAN Low Speed 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 Kb/s. Under normal vehicle operating conditions, the speed of the buss is 33.33 Kb/s. This protocol produces a simple pulse train sent out over the GMLAN low speed serial data bus. When a module pulls the buss high, 5 volts, this creates a dominant logic state or 0 on the buss. When the buss is pulled low, 0 volts, it is translated as a recessive logic state or 1. To wake the control modules connected to the GMLAN low speed serial data buss, a high voltage wake up pulse is sent out over the buss, the voltage level of the pules is +10 volts. Modules connected to the GMLAN low speed buss can be part of a virtual network as described in the previous paragraph. The modules on the GMLAN low speed serial data buss are connected to the buss in a parallel configuration.

Local Interconnect Network (LIN) Description

The driver door module (DDM) and the front passenger door module (FPDM) communicate with window motors on the local interconnect network bus 1 and the local interconnect network bus 2 circuits respectively. The DDM LIN buss is connected to all window motors on its side of the vehicle, while the FPDM LIN buss is connected to the other window motors. Communication on this network is only between the door modules and the window motors. The window motors are in effect modules. The window motor modules do not communicate on any other data buss; therefore the door modules, which also communicate on the low speed GMLAN serial data buss will perform all communication with each other, the motors, the BCM (gateway) and the scan tool including setting LIN buss DTCs.

Keyword 2000 Circuit Description

The keyword protocols utilize a single wire bi-directional data line between the module and the scan tool. The message structure is a request and response arrangement. The keyword serial data line is used for scan tool diagnostics of the climate control seat module (CCSM) only. Other modules on the vehicle do not exchange data on this circuit.

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. Pin 1 GMLAN low speed communications terminal
2. Pin 4 Scan tool power ground terminal
3. Pin 5 Common signal ground terminal
4. Pin 6 High speed GMLAN serial data bus (+) terminal
5. Pin 7 Keyword 2000 serial data bus terminal
6. Pin 14 High speed GMLAN serial data bus (-) terminal
7. Pin 16 Scan tool power, battery positive voltage terminal

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 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.

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
• Diagnostic Trouble Code (DTC) List - Vehicle
• GMLAN Wiring Repairs
• Moveable Window Schematics
• Checking Aftermarket Accessories
• Heated/Cooled Seat Schematics
• Splice Pack Connector End Views
• Instrument Panel Insulator Panel Replacement - Right Side
• Power Mode Description and Operation
• ABS Description and Operation
• Automatic Day-Night Mirror Description and Operation
• Cruise Control Description and Operation (Conventional Cruise Control)
• Cruise Control Description and Operation (Adaptive Cruise Control)
• 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
• Instrument Cluster Description and Operation
• Power Door Locks Description and Operation
• Steering Wheel Controls Description and Operation
• Keyless Entry System Description and Operation
• Automatic Transmission Shift Lock Control Description and Operation (Column Shift)
• Starting System Description and Operation
• SIR System Description and Operation
• Electronic Suspension Control Description and Operation
• Automatic Level Control Description and Operation (With F55)
• Immobilizer Description and Operation
• Content Theft Deterrent (CTD) Description and Operation
• Wiper/Washer System Description and Operation (Wiper and Washers)
• Wiper/Washer System Description and Operation (Heated Washer System)
• DTC B1000
• Data Link References
• Body Control System Description and Operation