DTC U0121 [MZR-CD (RF Turbo)]

BME010290000204

DTC U0121

Lost communication with ABS (ABS/TCS) HU/CM

DETECTION CONDITION

• PCM cannot receive any signals from ABS (ABS/TCS) HU/CM.
Diagnostic support note
• MIL does not come on.
• FREEZE FRAME DATA is not available.
• DTC is stored in the PCM memory.

POSSIBLE CAUSE

• Short to ground circuit between ABS (ABS/TCS) HU/CM terminal R and PCM terminal 39
• Short to ground circuit between ABS (ABS/TCS) HU/CM terminal O and PCM terminal 13
• Open circuit between ABS (ABS/TCS) HU/CM terminal R and PCM terminal 39
• Open circuit between ABS (ABS/TCS) HU/CM terminal O and PCM terminal 13
• Short to power circuit between ABS (ABS/TCS) HU/CM terminal R and PCM terminal 39
• Short to power circuit between ABS (ABS/TCS) HU/CM terminal O and PCM terminal 13
• Damaged ABS (ABS/TCS) HU/CM
• Damaged PCM

Diagnostic procedure

STEP

INSPECTION

ACTION

1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
• Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record FREEZE FRAME DATA on repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
• Check for related Service Information availability.
• Is any related Service Information available?
Yes
Perform repair or diagnosis according to available Service Information.
• If vehicle is not repaired, go to the next step.
No
Go to the next step.
3
VERIFY RELATED PENDING CODE OR STORED DTCS
• Turn the engine switch off, then to the ON position (Engine off).
• Verify the related PENDING CODE or stored DTCs.
• Is DTC U0073 present?
Yes
Go to the applicable DTC inspection.
No
Go to the next step.
4
INSPECT TCM CONNECTOR FOR POOR CONNECTION
• Turn the engine switch off.
• Disconnect the ABS (ABS/TCS) HU/CM connector.
• Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
• Is there any malfunction?
Yes
Repair the terminal, then go to Step 9.
No
Go to the next step.
5
CHECK CAN COMMUNICATION LINE FOR SHORT TO GROUND
• Inspect for continuity between the following terminals and body ground:
- ABS (ABS/TCS) HU/CM connector terminal R (wiring harness-side)
- ABS (ABS/TCS) HU/CM connector terminal O (wiring harness-side)
• Is there continuity?
Yes
Repair or replace the wiring harness, then go to Step 9.
No
Go to the next step.
6
CHECK CAN COMMUNICATION LINE FOR SHORT TO POWER
• Measure the voltage between the following terminals and body ground:
- ABS (ABS/TCS) HU/CM connector terminal O (wiring harness-side)
- ABS (ABS/TCS) HU/CM connector terminal R (wiring harness-side)
• Is the voltage B+?
Yes
Repair or replace the wiring harness, then go to Step 9.
No
Go to the next step.
7
INSPECT PCM CONNECTOR FOR POOR CONNECTION
• Turn the engine switch off.
• Disconnect the PCM connector.
• Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
• Is there any malfunction?
Yes
Repair the terminal, then go to Step 9.
No
Go to the next step.
8
CHECK CAN COMMUNICATION LINE FOR OPEN CIRCUIT
• Disconnect the PCM connector.
• Inspect for continuity between the following terminals:
- ABS (ABS/TCS) HU/CM connector terminal O (wiring harness-side) and PCM connector terminal 13 (wiring harness-side)
- ABS (ABS/TCS) HU/CM connector terminal R (wiring harness-side) and PCM connector terminal 39 (wiring harness-side)
• Is there continuity?
Yes
Repair or replace the wiring harness, then go to Step 9.
No
Go to the next step.
9
VERIFY TROUBLESHOOTING OF DTC U0121 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear the DTC from the PCM memory using the WDS or equivalent.
• Start the engine and warm it up completely.
• Is the PENDING CODE of same DTC present?
Yes
Replace the PCM, then go to the next step.
No
Go to the next step.
10
VERIFY AFTER REPAIR PROCEDURE
• Perform "After Repair Procedure".
• Is there any DTC present?
Yes
Go to the applicable DTC inspection.
No
Troubleshooting completed.