U0167

DTC U0100-U0299

Diagnostic Instructions

- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic approach.
- Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit Description

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

DTC Descriptors

DTC U0100: Lost Communication With Engine Control Module (ECM)
DTC U0101: Lost Communication With Transmission Control Module (TCM)
DTC U0167: Lost Communication With Vehicle Immobilizer Control Module

DTC Descriptors

This diagnostic procedure supports the following DTC:

- DTC U0101

Conditions for Running the DTC

- The ignition is ON.
- The DTC U0101 diagnostic runs continuously when the above condition is met.

Conditions for Setting the DTC

The engine control module (ECM) cannot communicate with the TCM.

Action Taken When the DTC Sets

- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the DTC

- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

Circuit/System Testing

1. Verify DTC U2105 is not set.
-> If DTC U2105 is set, refer to DTC U2105.
2. Using the DTC Descriptors above, determine the control module that is not communicating.
3. Ignition OFF, disconnect the harness connector of the control module that is not communicating.
4. Test for less than 10 between the control module ground circuits and ground.
-> If greater than the specified range, test the ground circuit for an open/high resistance.
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 control module for a short to ground. If the circuits test normal, replace the control module.
6. If equipped, 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 ignition voltage outputs of the control module for a short to ground. If the circuits test normal, replace the control module.
7. Test for less than 1 on the serial data circuits between the non-communicating control module and the control module that displays the DTC.
-> If greater than the specified range, test the serial data circuit for an open/high resistance.
8. If all circuits test normal, replace the control module that is not communication.