Inspection Procedure 1
Inspection Procedure 1: None of the front fog lights illuminates.
CAUTION:
Whenever the ECU is replaced, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
CIRCUIT OPERATION
When none of the front fog lights illuminates, the input signal circuit(s) below or the ETACS-ECU may be defective.
- Tail light switch
- Headlight switch
- Fog light switch
- Option coding information
TECHNICAL DESCRIPTION (COMMENT)
When the fog lights do not illuminate normally, the mentioned input signal circuit(s) or ETACS-ECU may be defective.
TROUBLESHOOTING HINTS
- Malfunction of the column switch
- Malfunction of the ETACS-ECU
- Damaged harness wires and connectors
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.
(1)
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 tool (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."
(2)Turn the ignition switch to the "ON" position.
(3)Read out the option coding information in ETACS-ECU Programming and Relearning).
(4)Check that the "Front fog light" is set to "YES."
(5)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 Symptom Chart).
STEP 3. Using scan tool MB991958, read the other system diagnostic trouble code.
Check if DTC is set to the ETACS-ECU.
(1)Turn the ignition switch to the "ON" position.
(2)Check whether the ETACS-ECU related DTC is set.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the DTC set?
YES Troubleshoot the ETACS-ECU (Refer to ETACS, Diagnosis Electronic Time and Alarm Control System (ETACS)).
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.
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 ETACS, Diagnosis - Inspection Procedure 11
"ETACS-ECU does not receive any signal from the column switch signal." Symptom Chart.
STEP 5. Check fog light relay connector A-15X for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q. Is fog light relay connector A-15X in good condition?
YES Go to Step 6.
NO Repair or replace the damaged component(s). Harness Connector Inspection.
STEP 6. Check the fog light relay.
Refer to Testing and Inspection.
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-15X.
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.
(1)Disconnect fog light relay connector A-15X and measure the voltage available at the relay box side of the connector.
(2)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-15X (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-15X (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). Harness Connector Inspection.
STEP 10. Check the wiring harness between fog light relay connector A-15X (terminal 1) and ETACS-ECU connector C-312 (terminal 4).
- Check the line for open circuit.
Q. Is the wiring harness between fog light relay connector A-15X (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-15X (terminal 3) and fog light (LH) connector A-43 (terminal 2) or fog light (RH) connector A-54 (terminal 2).
NOTE:
Also check intermediate connector A-50 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector A-50 is damaged, repair or replace the connector as described in Harness Connector Inspection Harness Connector Inspection.
- Check the power supply line for open circuit.
Q. Is the wiring harness between fog light relay connector A-15X (terminal 3) and fog light (LH) connector A-43 (terminal 2) or fog light (RH) connector A-54 (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-43 (terminal 1) or fog light (RH) connector A-54 (terminal 1) and ground.
NOTE:
Also check intermediate connector A-50 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector A-50 is damaged, repair or replace the connector as described in Harness Connector Inspection Harness Connector Inspection.
- Check the ground wires for open circuit.
Q. Is the wiring harness between fog light (LH) connector A-43 (terminal 1) or fog light (RH) connector A-54 (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 How to Cope With Intermittent Malfunctions).
NO Replace the ETACS-ECU.