Inspection Procedure M-3

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














CIRCUIT OPERATION

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

TECHNICAL DESCRIPTION (COMMENT)

If the signal is not normal, the fog lights do not work normally. If the signal is not normal, the fog light switch or the ETACS-ECU may be defective.

TROUBLESHOOTING HINTS

- The 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 fog light switch connector C-128 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q. Is fog light switch connector C-128 in good condition?

YES Go to Step 2.

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

STEP 2. Check the fog light switch.





Remove the fog light switch. Service and Repair.
Then check continuity between the switch terminals.





Q. Is the fog light switch in good condition?

YES Go to Step 3.

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

STEP 3. Check the ground circuit to the fog light switch. Measure the resistance at fog light switch connector C-128.





(1)Disconnect fog light switch connector C-128 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 fog light switch connector C-128 (terminal 2) and ground.

- Check the ground wire for open circuit.





Q. Is the wiring harness between fog light switch connector C-128 (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 fog light switch operates normally, a correct signal is sent from the 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). Harness Connector Inspection. If the fog light switch operates normally, a correct signal is sent from the fog light switch.

STEP 6. Check the wiring harness between fog light switch connector C-128 (terminal 1) and ETACS-ECU connector C-218 (terminal 54).

- Check the communication lines for open circuit and short circuit.









Q. Is the wiring harness between fog light switch connector C-128 (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. Encrypted Code Registration Criteria Table.
If the fog light switch operates normally, a correct signal is sent from the 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 fog light switch operates normally, a correct signal is sent from the fog light switch.