Inspection Procedure 2
Inspection Procedure 2: Neither right nor left automatic leveling operates.CAUTION: Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
Headlight Relay (LOW) Signal And Communication Meter Signal Circuit Part 1:
Headlight Relay (LOW) Signal And Communication Meter Signal Circuit Part 2:
OPERATION
When a vehicle is at a standstill or being driven at a constant speed for 12 seconds or more (except on rough road), the headlight automatic leveling ECU inputs a headlight relay (LOW) signal, vehicle speed signal, and height signal for judgment and operates the headlight leveling.
NOTE: The automatic leveling during driving at a constant speed operates only once after starting driving. The automatic leveling does not work if the vehicle pitch angle during driving at a constant speed and the vehicle pitch angle when the vehicle is stopped are the same.
TECHNICAL DESCRIPTION (COMMENT)
Assuming that the automatic leveling DTC is not set, if neither right nor left automatic leveling operates, the headlight automatic leveling-ECU, wiring harness and connector(s) between the headlight automatic leveling-ECU and the headlight relay (LOW), the combination meter (vehicle speed signal abnormality), or wiring harness and connector(s) between the headlight automatic leveling-ECU and the combination meter may have a problem.
TROUBLESHOOTING HINTS
- Malfunction of the headlight automatic leveling-ECU
- Malfunction of combination meter
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
DIAGNOSIS
Required Special Tools:
- MB992006: Extra fine probe
- MB991223: Harness set
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool MB991958, read the diagnostic trouble code.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958. Refer to "How to connect scan too (M.U.T.-III)."
2. Turn the ignition switch to the "ON" position.
3. Check whether the ETACS-ECU related DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is ETACS-ECU code set?
YES: Go to Step 2.
NO: Refer to Inspection Procedure 1 "Diagnostic trouble code is not set".
STEP 2. Check combination meter.
Q: Does the speedometer operate?
YES: Go to Step 3.
NO: Diagnosis the combination meter (Refer to Instrument Cluster/Carrier - Diagnosis). On completion, go to Step 3.
STEP 3. Check headlight automatic leveling-ECU connector C-110 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is headlight automatic leveling-ECU connector C-110 in good condition?
YES: Go to Step 4.
NO: Repair the damaged parts.
STEP 4. Voltage measurement at headlight automatic leveling-ECU connector C-110.
1. Disconnect the connector, and measure at the wiring harness-side connector.
2. Turn "ON" the headlight switch.
3. Voltage between headlight automatic leveling-ECU connector C-110 (terminal No. 6) and body ground
The voltage should measure approximately 2 volts (battery positive voltage).
Q: Does the voltage measure battery voltage?
YES: Go to Step 6.
NO: Go to Step 5.
STEP 5. Check wiring harness between headlight automatic leveling-ECU connector C-110 (terminal No. 6) and headlight relay (LOW) connector A-28X (terminal No. 3).
Q: Are the wiring harness between headlight automatic leveling-ECU connector C-110 (terminal No. 6) and headlight relay (LOW) connector A-28X (terminal No. 3) in good condition?
YES: Go to Step 6.
NO: Repair the wiring harness.
STEP 6. Check combination meter connector C-03 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is combination meter connector C-03 in good condition?
YES: Go to Step 7.
NO: Repair the damaged parts.
STEP 7. Check wiring harness between headlight automatic leveling-ECU connector C-110 (terminal No. 9) and combination meter connector C-03 (terminal No. 20).
NOTE: Prior to the wiring harness inspection, check intermediate connector C-34, and repair if necessary.
Q: Are the wiring harness between headlight automatic leveling-ECU connector C-110 (terminal No. 9) and combination meter connector C-03 (terminal No. 20) in good condition?
YES: Go to Step 8.
NO: Repair the wiring harness.
STEP 8. Retest the system.
Check that the automatic leveling operates normally.
Q: Is the check result normal?
YES: The trouble can be an intermittent malfunction (Refer to How to use Troubleshooting/ inspection Service Points - How to Cope with Intermittent Malfunction).
NO: Replace the headlight automatic leveling-ECU.