Inspection Procedure O-5

INSPECTION PROCEDURE O-5: The fog light switch signal is not sent to the ETACS-ECU.






CIRCUIT OPERATION
The ETACS-ECU operates the fog lights according to the input signal from the fog light switch.

TECHNICAL DESCRIPTION (COMMENT)
The fog lights will not work normally if the fog light switch input signal is an error.

TROUBLESHOOTING HINTS
- The fog light switch may be defective
- The ETACS-ECU may be defective
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

DIAGNOSIS
Required Special Tools:
- MB991223: Test Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991529: Diagnostic Trouble Code Check Harness










STEP 1. Check the fog light switch.

Q: Is the fog light switch in good condition?

YES : Go to Step 2.

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. The fog light switch input signal should be able to be checked and the fog lights should work normally.

STEP 2. Check the ground circuit to the fog light switch. Test at fog light switch connector C-139.




1. Disconnect the fog light switch connector C-139 and measure the resistance available at the wiring harness side of the connector.




2. Measure the resistance between terminal 7 and ground.
- The resistance should equal 2 ohms or less.

Q: Is the measured resistance 2 ohms or less?

YES : Go to Step 5.

NO : Go to Step 3.




STEP 3. Check the fog light switch connector C-139 for loose, corroded or damaged terminals, or terminals pushed back in the connector

Q: Is fog light switch connector C-139 in good condition?

YES : Go to Step 4.

NO : Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Diagnostic AidsThe fog light switch input signal should be able to be checked and the fog light should work normally.




STEP 4. Check the wiring harness between fog light switch connector C-139 (terminal 7) and ground.

NOTE: Also check joint connector C-141 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If joint connector C-141 is damaged, repair or replace the damaged components) Refer to Harness Connector Inspection.

Q: Are the wiring harness between fog light switch connector C-139 (terminal 7) and ground in good condition?

YES : No action is necessary and testing is complete.

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. The fog light switch input signal should be able to be checked and the fog lights should work normally.







STEP 5. Check the fog light switch connector C-139 and ETACS-ECU connector C-318 for loose, corroded or damaged terminals, or terminals
pushed back in the connector.

Q: Are fog light switch connector C-139 and ETACS-ECU connector C-318 in good condition?

YES : Go to Step 6.

NO : Repair or replace the damaged components). Refer to Harness Connector Inspection. The fog light switch input signal should be able to be checked and the fog lights should work normally.







STEP 6. Check the wiring harness between fog light switch connector C-139 (terminal 6) and ETACS-ECU connector C-318 (terminal 54).

Q: Is the wiring harness between fog light switch connector C-139 (terminal 6) and ETACS-ECU connector C-318 (terminal 54) in good condition?

YES : Replace the ETACS-ECU. The fog light switch input signal should be able to be checked and the fog lights should work normally.

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. The fog light switch input signal should be able to be checked and the fog lights should work normally.