Inspection Procedure M-3

INSPECTION PROCEDURE M-3: ETACS-ECU does not receive any signal from the front fog light switch.

Front Fog Light Switch Input Circuit:

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

TECHNICAL DESCRIPTION (COMMENT)
If the signal is not normal, the front fog lights do not work normally. If the signal is not normal, the front fog light switch or the ETACS-ECU may be defective.

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

DIAGNOSIS

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

STEP 1. Check front fog light switch connector C-127 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is front fog light switch connector C-127 in good condition?

YES : Go to Step 2.

NO : Repair or replace the damaged component(s). Repair the front fog light switch. If the front fog light switch operates normally, a correct signal is sent from the front fog light switch.

STEP 2. Check the front fog light switch.







Remove the front fog light switch. Then check continuity between the switch terminals.







Q: Is the front fog light switch in good condition?

YES : Go to Step 3.

NO : Repair the front fog light switch. If the front fog light switch operates normally, a correct signal is sent from the front fog light switch.

STEP 3. Check the ground circuit to the front fog light switch. Measure the resistance at front fog light switch connector C-127.







1. Disconnect front fog light switch connector C-127 and measure the resistance available at the wiring harness side of the connector.







2. Measure the resistance value between terminal 2 and ground.
- The resistance should be 2 ohms or less.

Q: Is the measured resistance 2 ohms or less?

YES : Go to Step 5.

NO : Go to Step 4.

STEP 4. Check the wiring harness between front fog light switch connector C-127 (terminal 2) and ground.







Q: Is the wiring harness between front fog light switch connector C-127 (terminal 2) 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. If the front fog light switch operates normally, a correct signal is sent from the front fog light switch.

STEP 5. Check ETACS-ECU connector C-218 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is ETACS-ECU connector C-218 in good condition?

YES : Go to Step 6.

NO : Repair or replace the damaged component(s). If the front fog light switch operates normally, a correct signal is sent from the front fog light switch.

STEP 6. Check the wiring harness between front fog light switch connector C-127 (terminal 1) and ETACS-ECU connector C-218 (terminal 54).







Q: Is the wiring harness between front fog light switch connector C-127 (terminal 1) and ETACS-ECU connector C-218 (terminal 54) in good condition?

YES : Replace the ETACS-ECU. When the ETACS-ECU is replaced, register the encrypted code. If the front fog light switch operates normally, a correct signal is sent from the front fog light switch.

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. If the front fog light switch operates normally, a correct signal is sent from the front fog light switch.