Inspection Procedure P-8

The ETACS-ECU does not Receive a Signal from Hood Switch.

Hood Switch Input Circuit:

CIRCUIT OPERATION
The ETACS-ECU operates the theft-alarm system according to signal from the hood switch.

TECHNICAL DESCRIPTION (COMMENT)
If the signal is not normal, the theft-alarm system does not work normally.

TROUBLESHOOTING HINTS
- The hood 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: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicles communication interface (V.C.I.)
- MB991827: MUT-III USB cable
- MB991911: MUT-III Main harness B




STEP 1. Check hood switch connector A-23 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is hood switch connector A-23 in good condition?

YES: Go to Step 2.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. If the theft-alarm system operates normally, it indicates that a correct signal is sent from the hood switch.







STEP 2. Check the hood switch.
Remove the hood switch. Then check continuity between the switch terminals.

Q: Is the hood switch in good condition?

YES: Go to Step 3.

NO: Replace the hood switch. If the theft-alarm system operates normally, it indicates that a correct signal is sent from the hood switch.

STEP 3. Check the ground circuit to the hood switch. Measure the resistance at hood switch connector A-23.




1. Disconnect hood switch connector A-23 and measure the resistance available at the wiring harness side of the connector.




2. Measure the resistance value between terminal 1 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 4.




STEP 4. Check the wiring harness between hood switch connector A-23 (terminal 1) and ground.

Q: Is the wiring harness between hood switch connector A-23 (terminal 1) and the ground in good condition?

YES: No action to be taken.

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 theft-alarm system operates normally, it indicates that a correct signal is sent from the hood switch.




STEP 5. Check ETACS-ECU connector C-117 for damage.

Q: Is ETACS-ECU connector C-117 in good condition?

YES: Go to Step 6.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. If the theft-alarm system operates normally, it indicates that a correct signal is sent from the hood switch.










STEP 6. Check the wiring harness between hood switch connector A-23 (terminal 2) and ETACS-ECU connector C-117 (terminal 24).

NOTE: Also check intermediate connector C-89 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-89 is damaged, Repair or replace the damaged component(s) as described in Harness Connector Inspection.

Q: Is the wiring harness between hood switch connector A-23 (terminal 2) and ETACS-ECU connector C-117 (terminal 24) in good condition?

YES: Replace the ETACS-ECU. If the theft-alarm system operates normally, it indicates that a correct signal is sent from the hood 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 theft-alarm system operates normally, it indicates that a correct signal is sent from the hood switch.