Inspection Procedure P-8

INSPECTION PROCEDURE P-8: ETACS-ECU Does Not Receive Any Signal From The 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 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 Tool:
- MB991223: Harness Set
- MB992006: Extra Fine Probe

STEP 1. Check hood switch connector A-15 for loose, corroded or damaged terminals, or terminals pushed back in the connector.






Q: Is hood switch connector A-15 in good condition?

YES: Go to Step 2.

NO: Repair or replace the damaged component(s). If the theft-alarm system operates normally, 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, 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-15.






1. Disconnect hood switch connector A-15 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 hood switch connector A-15 (terminal 2) and ground.

- Check the ground wire for open circuit.






Q: Is the wiring harness between hood switch connector A-15 (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 theft-alarm system operates normally, a correct signal is sent from the hood switch.

STEP 5. Check ETACS-ECU connector C-217 for loose, corroded or damaged terminals, or terminals pushed back in the connector.






Q: Is ETACS-ECU connector C-217 in good condition?

YES: Go to Step 6.

NO: Repair or replace the damaged component(s). If the theft-alarm system operates normally, a correct signal is sent from the hood switch.

STEP 6. Check the wiring harness between hood switch connector A-15 (terminal 1) and ETACS-ECU connector C-217 (terminal 24).

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














NOTE: Also check intermediate connector C-31 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-31 is damaged, repair or replace the damaged component(s).

Q: Is the wiring harness between hood switch connector A-15 (terminal 1) and ETACS-ECU connector C-217 (terminal 24) in good condition?

YES: Replace the ETACS-ECU. When the ETACS-ECU is replaced, register the encrypted code. 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, a correct signal is sent from the hood switch.