Circuit Description
The controller area network (CAN) serial data line is a high speed serial data bus used to communicate information between the engine control module (ECM) and the transmission control module (TCM). Typical data-transmission speeds must be high enough to ensure that the required real-time response is maintained.
The CAN serial data line does not communicate with the scan tool via the DLC. CAN serial data information is interpreted by the ECM and transmitted to the serial data line by the ECM.
Conditions for Running the DTC
The CAN circuits are monitored continuously by the modules on the circuit. The only requirement is that the modules are in a RUN power mode.
Conditions for Setting the DTC
The module setting the DTC has attempted to establish communications on the CAN circuits for more than 5 seconds.
Action Taken When the DTC Sets
The DTC is set as both current and history, the modules on the CAN network each take separate actions as listed:
| • | Engine Control Module (ECM): |
| - | Turn ON the MIL during the third consecutive drive cycle with the error detected. |
| - | Record the operating conditions at the time of turning on the MIL and store the data as freeze frame information. |
| • | Transmission Control Module (TCM): |
| - | SERVICE TRANSMISSION message is displayed when the first error is detected. |
| - | Transmission operates in the default mode. |
Conditions for Clearing the MIL/DTC
| • | A current DTC clears and the MIL is turned OFF when the fault is no longer present. |
| • | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the fault. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This DTC sets when a communication fault exists between the ECM and the TCM. Inspect for DTCs U2100, U2102 or U2106. If any of these DTCs are present, diagnose them first.
-
If a module is not awake, the modules expecting to receive data cannot detect the presence of the transmitting module.
-
The TCM needs time to reset memory.
Step | Action | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Data Link Connector Schematics Connector End View Reference: Master Electrical Component List and Inline Harness Connector End Views | |||||||||||
1 | Did you perform the Diagnostic System Check for the system exhibiting the symptom? | Go to Step 2 | Go to Control Module References in Body Control System for the applicable diagnostic system check | ||||||||
Does the scan tool indicate that DTC U2100 or DTCs U2106 as either current or history DTCs? | Go to Step 3 | ||||||||||
Test the following circuits of the TCM for an open or high resistance:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 4 | |||||||||
4 | Test the controller area network (CAN) serial data low circuit and the CAN serial data high circuit between the engine control module (ECM) and transmission control module (TCM) for the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 5 | ||||||||
5 | Inspect for poor connections at the harness connector of the module that is not communicating. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 6 | ||||||||
6 |
Important: Perform the set-up procedure for the replaced control module, if required. Replace the control module that is not communicating. Refer to Control Module References in Body Control System. Did you complete the replacement? | Go to Step 7 | -- | ||||||||
Does the DTC reset? | Go to Step 2 | System OK | |||||||||
