Code No.31 Malfunction of the Levelling Unit


caution Before replacing the ECU, ensure that the communication circuit is normal.










TROUBLE JUDGMENT



COMMENTS ON TROUBLE SYMPTOM



PROBABLE CAUSES



  • Malfunction of headlamp assembly (headlamp levelling unit)
  • Malfunction of the headlamp automatic levelling ECU
  • Damaged harness wires and connectors

DIAGNOSIS PROCEDURE


STEP 1. Connector check: A-37 headlamp levelling unit (LH) connector, C-112 headlamp automatic levelling ECU connector


Q. Is the check result normal?





STEP 2. Wiring harness check between the A-37 headlamp levelling unit (LH) connector terminal No. 10 and the C-112 headlamp automatic levelling ECU connector terminal No. 3



  • Check the signal lines for open circuit and short circuit.

Q. Is the check result normal?





STEP 3. Check whether the diagnosis code is reset.


Q. Is diagnosis code No. 31 set?





STEP 4. Connector check: A-54 headlamp levelling unit (RH) connector


Q. Is the check result normal?





STEP 5. Wiring harness check between the A-54 headlamp levelling unit (RH) connector terminal No. 10 and the C-112 headlamp automatic levelling ECU connector terminal No. 12



  • Check the signal lines for open circuit and short circuit.

Q. Is the check result normal?





STEP 6. Check whether the diagnosis code is reset.


Q. Is diagnosis code No. 31 set?





STEP 7. Check whether the diagnosis code is reset.



Q. Is diagnosis code No. 31 set?





STEP 8. Check whether the diagnosis code is reset.



Q. Is diagnosis code No. 31 set?