Communications

U0121-LOST COMMUNICATION WITH ANTI-LOCK BRAKE MODULE (ABS)





For a complete wiring diagram refer to Diagrams/Electrical.

- When Monitored:

With the ignition on.

Battery voltage between 10 and 16 volts.

IOD fuse installed.

TIPM is configured correctly.

- Set Condition:

Bus messages not received from the ABS for approximately 2 to 5 seconds.





Diagnostic Test

1. VERIFY DTC IS ACTIVE

NOTE: Ensure the IOD fuse is installed and battery voltage is between 10 and 16 volts before proceeding.

With the scan tool, read active DTCs.

Is this DTC active?

Yes

- Go To 2

No

- Refer to the Stored Lost Communication diagnostic procedure. Stored Lost Communication DTCs

2. CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS

With the scan tool, read all active DTCs from all modules.

NOTE: Check for TIPM configuration, CAN C hardware electrical, VIN Missing/Mismatch, battery or ignition related DTCs.

Does the scan tool display any active DTCs to the conditions listed above?

Yes

- Diagnose and repair the DTC.

No

- Go To 3

3. VERIFY THAT THE ABS IS ACTIVE ON THE BUS

Turn the ignition on.

With the scan tool, select Network Diagnostics.

Verify that the ABS is active on the bus.

Is the ABS active on the bus?

Yes

- Go To 4

No

- Perform the No Response diagnostic procedure.

4. CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS

With the scan tool, select Network Diagnostics.

Is there more than one module with active DTCs "Logged Against" the ABS?

Yes

- Replace/update the ABS.
- Perform the ABS VERIFICATION TEST. ABS Verification Test

No

- Go To 5

5. CLEAR DTC IN MODULE SETTING FAULT

With the scan tool, select the module setting the DTC against the ABS.

Clear active DTCs.

Is this DTC still active?

Yes

- Replace/update the module that set this DTC.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 6

6. CYCLE IGNITION

Cycle the ignition from RUN to OFF three times ending with the key in the RUN position.

Does this DTC become active?

Yes

- Go To 7

No

- The condition is not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals.
- Perform the appropriate VERIFICATION TEST.

7. CHECK FOR ADDITIONAL LOST COMMUNICATION FAULTS

With the scan tool, select Network Diagnostics.

Does the TIPM and other CAN C BUS modules show Lost Communication with the remaining CAN C BUS modules?

Yes

- Go To 8

No

- Replace/update the module that set this DTC.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

8. (D65) CAN C BUS (+) CIRCUIT SHORTED TO VOLTAGE

Measure the voltage between the (D65) CAN C Bus (+) circuit and ground.

Is the voltage above 5 volts?

Yes

- Repair the (D65) CAN C Bus (+) circuit for a short to voltage.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 9

9. (D64) CAN C BUS (-) CIRCUIT SHORTED TO GROUND

Turn the ignition off.

Measure the resistance between ground and the (D64) CAN C Bus (-) circuit.

Is the resistance below 10K Ohms?

Yes

- Repair the (D64) CAN C Bus (-) circuit for a short to ground.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Replace/update the module that set this DTC.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test