Powertrain Control Module (PCM), NGC

U0121 - LOST COMMUNICATION WITH ANTI-LOCK BRAKE MODULE







- When Monitored:

- With the ignition on
- Battery voltage between 10 and 16 volts
- IOD fuse installed
- Set Condition:
If the PCM fails to receive bus messages from the ABS M for approximately 500 ms.





1. VERIFY DTC IS ACTIVE

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

1. Turn the ignition on.
2. With the scan tool, select View DTCs.

Is this DTC Active?

Yes

- Go To 2

No

- Perform the Stored Lost Communication test procedure. Stored Lost Communication DTCs

2. CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS
1. With the scan tool, read all active DTCs from all CAN C Bus modules.

NOTE: Check for 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(s).

No

- Go To 3

3. VERIFY THAT THE ABS IS ACTIVE ON THE BUS
1. With the scan tool, select ECU View.
2. Verify that the ABS is active on the bus.

Is the ABS active on the bus?

Yes

- Go To 4

No

- Manufacturer Code Charts No Response related diagnostic procedures.

4. CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS
1. With the scan tool, select Network View and select Advanced.

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

Yes

- Replace/update the ABS.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Replace the PCM.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test