U0151
DTC U0100-U0299
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC U0100
- Lost Communication With Engine Control Module (ECM)
DTC U0101
- Lost Communication With Transmission Control Module (TCM)
DTC U0140
- Lost Communication With Body Control Module
DTC U0151
- Lost Communication With Restraints Control Module
DTC U0155
- Lost Communication With Instrument Panel Cluster (IPC) Control Module
DTC U0184
- Lost Communication With Radio
Diagnostic Fault Information
Circuit Description
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. Each message contains the identification number of the transmitter module.
Conditions for Running the DTC
* Voltage supplied to the modules is in the normal operating voltage range.
* The vehicle power mode requires serial data communication to occur.
Conditions for Setting the DTC
A supervised periodic message that includes the transmitter module availability has not been received.
Action Taken When the DTC Sets
The module uses a default value for the missing parameter.
Conditions for Clearing the DTC
* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
Diagnostic Aids
* A poor connection at the inoperative module may cause this code to set.
* An improperly powered module may cause this code to set.
* 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.
Reference Information
Schematic Reference
Data Communication Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Component Connector End Views)
Description and Operation
Data Link Communications Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for Scan Tool Information
Circuit/System Testing
1. Using the DTC Descriptor and Diagnostic Aids above, determine the module that is not communicating that should be tested.
2. Ignition OFF, disconnect the harness connector of the module that is not communicating.
3. Ignition ON, verify that a test lamp illuminates between all battery positive voltage circuits and ground.
• If the test lamp does not illuminate, repair 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 faulty module.
4. Verify that a test lamp illuminates between all ignition voltage circuits and ground.
• If the test lamp does not illuminate, repair 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 faulty module.
5. Test for less than 1 ohm of resistance between the module ground circuits and ground.
• If greater than 1 ohm, repair the ground circuit for open/high resistance.
6. Test for less than 1 ohm of resistance in the GMLAN serial data circuit(s) between the non-communicating module and the module that displays the DTC.
• If greater than 1 ohm of resistance, test the GMLAN serial data circuit(s) for open/high resistance.
7. If all circuits test normal, replace the module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Control Module References (Programming and Relearning) for module replacement, setup, and programming
* GMLAN Wiring Repairs (Component Tests and General Diagnostics)