Inspection Procedure 1: None of the front fog lights illuminates: Diagnosis
Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
- STEP 1. ETACS-ECU coding data check. 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.
- Connect scan tool MB991958. Refer to "HOW TO CONNECT SCAN TOO (M.U.T.-III) ."
- Turn the ignition switch to the "ON" position.
- Read out the option coding information in ETACS-ECU (Refer to CODING LIST ).
- Check that the "Front fog light" is set to "YES."
- Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the ETACS-ECU coding data normal?
- YES: Go to Step 2.
- NO: Operate scan tool MB991958 to set the option coding "Front fog light" to "Yes," and check the trouble symptom.
- STEP 2. Check that the tail/stop lights and headlights operate.
Check that the tail/stop lights and headlights illuminate normally.
Q: Do the tail/stop lights and headlights operate normally?
- YES: Go to Step 3.
- NO: Check the tail/stop lights and the headlights (Refer to TROUBLE SYMPTOM CHART ).
- STEP 3. Using scan tool MB991958, read the other system diagnostic trouble code.
Check if DTC is set to the ETACS-ECU.
- Turn the ignition switch to the "ON" position.
- Check whether the ETACS-ECU related DTC is set.
- Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
- YES: Troubleshoot the ETACS-ECU (Refer to DIAGNOSIS ).
- NO: Go to Step 4.
- STEP 4. Using scan tool MB991958, check data list.
Use the ETACS-ECU data list to check the signals related to the fog light function.
- Turn the ignition switch to the "ACC" position.
- Turn the fog light switch to ON.
Item No. Item name Normal condition Item 212 Front fog light ON
Q: Does scan tool MB991958 display the items "Front fog light" as normal condition?
- YES: Go to Step 5.
- NO: Troubleshoot the ETACS-ECU. Refer to INSPECTION PROCEDURE 11: ETACS-ECU DOES NOT RECEIVE ANY SIGNAL FROM THE COLUMN SWITCH SIGNAL .
- STEP 5. Check fog light relay connector A-11X for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is fog light relay connector A-11X in good condition?
- YES: Go to Step 6.
- NO: Repair or replace the damaged component(s). Refer to HARNESS CONNECTOR INSPECTION .
- STEP 6. Check the fog light relay.
Refer to FRONT FOG LIGHT RELAY CHECK .
Q: Is the fog light relay in good condition?
- YES: Go to Step 7.
- NO: Replace the fog light relay.
- STEP 7. Check the battery power supply circuit to the fog light relay. Measure the voltage at fog light relay connector A-11X. CAUTION: The top and bottom of the fog light relay are difficult to identify. Prior to inspection, confirm the triangle mark on the relay box.
- Disconnect fog light relay connector A-11X and measure the voltage available at the relay box side of the connector.
- Measure the voltage between terminal 2 and ground, and between terminal 4 and ground.
- 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 9.
- NO: Go to Step 8.
- STEP 8. Check the wiring harness between fog light relay connector A-11X (terminal 2 and 4) and fusible link (36).
- Check the power supply line for open circuit.
Q: Is the wiring harness between fog light relay connector A-11X (terminal 2 and 4) and fusible link (36) in good condition?
- YES: Go to Step 13.
- 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 9. Check ETACS-ECU connector C-312 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is ETACS-ECU connector C-312 in good condition?
- YES: Go to Step 10.
- NO: Repair or replace the damaged component(s). Refer to HARNESS CONNECTOR INSPECTION .
- STEP 10. Check the wiring harness between fog light relay connector A-11X (terminal 1) and ETACS-ECU connector C-312 (terminal 4).
Q: Is the wiring harness between fog light relay connector A-11X (terminal 1) and ETACS-ECU connector C-312 (terminal 4) in good condition?
- YES: Go to Step 11.
- 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 11. Check the wiring harness between fog light relay connector A-11X (terminal 3) and fog light (LH) connector A-34 (terminal 2) or fog light (RH) connector A-44 (terminal 2). NOTE: Also check intermediate connector A-39 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector A-39 is damaged, repair or replace the connector . Refer to HARNESS CONNECTOR INSPECTION .
- Check the power supply line for open circuit.
Q: Is the wiring harness between fog light relay connector A-11X (terminal 3) and fog light (LH) connector A-34 (terminal 2) or fog light (RH) connector A-44 (terminal 2) in good condition?
- YES: Go to Step 12.
- 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 12. Check the wiring harness between fog light (LH) connector A-34 (terminal 1) or fog light (RH) connector A-44 (terminal 1) and ground. NOTE: Also check intermediate connector A-39 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector A-39 is damaged, repair or replace the connector . Refer to HARNESS CONNECTOR INSPECTION .
- Check the ground wires for open circuit.
Q: Is the wiring harness between fog light (LH) connector A-34 (terminal 1) or fog light (RH) connector A-44 (terminal 1) and ground in good condition?
- YES: Go to Step 13.
- 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 13. Retest the system.
Q: Does the fog lights illuminate in good condition?
- YES: The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
- NO: Replace the ETACS-ECU.