Inspection Procedure 9

Inspection Procedure 9: The Rear Display Does Not Change To Nighttime Brightness When The Headlights Are Illuminated.

Rear Display Unit Communication Circuit:

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- 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

STEP 1. Using scan tool MB991958, read the combination meter diagnostic trouble code.

Check if DTC is set to the combination meter.

Q: Is the DTC set?

YES : Diagnose the combination meter. On completion, go to Step 2.

NO : Go to Step 2.

STEP 2. Using scan tool MB991958, read the ETACS-ECU diagnostic trouble code.

Check if the DTC is set to the ETACS-ECU.

Q: Is the DTC set?

YES : Diagnose the ETACS-ECU, and then go to Step 3. Diagnostic Trouble Code Descriptions

NO : Go to Step 3.

STEP 3. 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 4.

NO : Repair or replace the damaged component(s). Refer to general (electrical), Harness Connector Inspection.

STEP 4. Check the power supply circuit to the combination meter. Measure the voltage at combination meter connector C-03.

1. Disconnect combination meter connector C-03, and measure the voltage available at the wiring harness-side connector.
2. Turn the ignition switch to the "LOCK" (OFF) position.




3. Measure the voltage terminal No.24 and the body ground.

OK: The voltage should measure approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts (battery positive voltage)?

YES : Go to Step 6.

NO : Go to Step 5.

STEP 5. Check the wiring harness between ETACS-ECU connector C-317 (terminal 9) and combination meter connector C-06 (terminal 24).

- Check the power supply line for open circuit.

Q: Is the wiring harness between ETACS-ECU connector C-317 (terminal 2) and combination meter connector C-03 (terminal 24) in good condition?

YES : Replace the ETACS-ECU, then go to Step 6.

NO : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.

STEP 6. Check the wiring harness between combination meter connector C-03 (terminal 23) and rear display unit connector D-06 (terminal 5).

NOTE: Also check intermediate connector D-123 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector D-123 is damaged, repair or replace the connector as described in general (electrical), Harness Connector Inspection.

- Check the power supply line for open circuit.

Q: Is the wiring harness between combination meter connector C-03 (terminal 23) and rear display unit connector D-06 (terminal 5) in good condition?

YES : Replace the rear display unit.

NO : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.