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), body control module (BCM), electronic brake control module (EBCM), 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 data link connector (DLC). CAN serial data information is interpreted by the BCM and transmitted to the serial data line by the BCM.
Each module on the CAN serial data circuit learns the identity of the other modules on the circuit. If a module stops communicating after all modules have initiated for the ignition cycle, other modules set a DTC specific for the module not communicating:
| • | DTC U2105, can not communicate with the ECM |
| • | DTC U2106, can not communicate with the TCM |
| • | DTC U2107, can not communicate with the BCM |
| • | DTC U2108, can not communicate with the EBCM |
Control Module | ID Number |
|---|---|
Engine Control Module (ECM) | 05 |
Transaxle Control Module (TCM) | 06 |
Body Control Module (BCM) | 07 |
Electronic Brake Control Module (EBCM) | 08 |
Conditions for Running the DTC
| • | Supply voltage to the modules are in the normal operating range. |
| • | The vehicle is in the RUN power mode. |
Conditions for Setting the DTC
The module setting the DTC has attempted to establish communications on the CAN circuits more than 7 times.
Action Taken When the DTC Sets
Besides storing the DTC as both current and history and using default values for missing parameters, the modules on the CAN network each take separate actions as listed:
| • | Engine control module (ECM) |
| - | Turn ON the MIL during the second 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. |
| • | Transaxle control module (TCM) |
| Send a request to the ECM to turn ON the MIL during the second consecutive drive cycle with the error detected. |
| • | Electronic brake control module (EBCM) |
| - | The traction control system (TCS) is disabled. |
| - | Turn OFF the TCS LED in the TCS switch. |
| - | The EBCM may also set C0236, C0241, C0276, when a U code is current in the EBCM. |
| • | Body control module (BCM) |
| - | Turn ON the MIL during the second 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. |
Conditions for Clearing the DTC
The MIL is cleared, turned OFF, and the DTC is cleared by a different strategy for each module.
| • | ECM |
| - | If the fault is not detected 3 consecutive drive cycles, the current DTC is cleared and the MIL is turned OFF. |
| - | The history DTC is cleared if the malfunction does not reoccur for 40 consecutive drive cycles. |
| - | The history DTC is cleared if there is a KAM reset (battery disconnected). |
| • | TCM |
| - | If the fault is not detected one consecutive drive cycle, the current DTC is cleared. |
| - | The history DTC is cleared if the malfunction does not reoccur for 40 consecutive drive cycles. |
| • | EBCM |
| - | If the fault is not detected on consecutive drive cycle, the current DTC is cleared and the TCS LED is illuminated. |
| - | The history DTC is cleared if the malfunction does not reoccur for 40 consecutive drive cycles. |
| • | BCM |
| - | If the fault is not detected 3 consecutive drive cycles, the current DTC is cleared and the MIL is turned OFF. |
| - | The history DTC is cleared if the malfunction does not reoccur for 40 consecutive drive cycles. |
| - | The history DTC is cleared if there is a KAM reset (battery disconnected). |
Step | Action | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Data Link Connector Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems. | |||||||||||
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 | ||||||||
2 |
Does the scan tool indicate that DTC U2100 or DTCs in the range of U2102-U2104 as either current or history DTCs? | Go to Step 3 | |||||||||
3 |
Did you find and correct the concern? | Go to Step 4 | Go to Step 5 | ||||||||
4 |
Does the DTC reset? | Go to Step 7 | System OK | ||||||||
5 | Test all CAN serial data circuits between the module setting the DTC and the module that is not communicating for opens, shorts to voltage, shorts to ground, and shorts between CAN circuits. Did you find and correct the concern? | Go to Step 4 | Go to Step 6 | ||||||||
6 | Inspect for poor connections at the harness connector of the module that is not communicating. Did you find and correct the condition? | Go to Step 7 | Go to Step 10 | ||||||||
7 | Inspect the connector of the module recording the DTC. Did you find and correct the condition? | Go to Step 8 | Go to Step 9 | ||||||||
8 |
Does the DTC reset? | Go to Step 2 | System OK | ||||||||
9 |
Important: Perform the programming or setup procedure for the replaced control module, if required. Replace the control module that has set the DTC. Refer to Control Module References in Body Control System for the applicable replacement procedure. Did you complete the replacement? | Go to Step 8 | -- | ||||||||
10 |
Important: Perform the programming or setup 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 for the applicable replacement procedure. Did you complete the replacement? | Go to Step 4 | -- | ||||||||
