Test L: No Controller Area Network (CAN) Communications

PINPOINT TEST L: NO CONTROLLER AREA NETWORK (CAN) COMMUNICATIONS

L1-L3:

L4-L7:

L8-L10:

L11-L13:

L14-L15:

L15-L18:

L19-L21:

Normal Operation
The following modules communicate using the CAN:
- instrument cluster
- anti-lock brake system (ABS) module
- powertrain control module (PCM)
- fire suppression module (FSM) (if equipped)

The CAN has an unshielded twisted pair cable, data bus plus circuit 1827 (WH/LG) and data bus minus circuit 1828 (PK/LG). The CAN permits inter-module communications between the data link connector (DLC), the instrument cluster, the PCM, the ABS module and the FSM (if equipped). When the diagnostic tool communicates to modules on the CAN, the diagnostic tool must request all information or initiate module commands.

Check the CAN circuits between each network module and the DLC C251. The total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open in one of the CAN circuits, damage to the DLC C251, damage to one of the module connectors, or a problem in an in-line connector.

Possible Causes
- CAN data plus circuit 1827 (WH/LG) open, short to ground, or short to voltage
- CAN data minus circuit 1828 (PK/LG) open, short to ground, or short to voltage
- DLC C251
- instrument cluster C2220
- ABS module C135
- PCM C175b
- FSM C3281a (if equipped)
- instrument cluster
- ABS module
- PCM
- FSM (if equipped)