Inspection Procedure E-2

Keyless Entry System: The front dome light, the turn-signal lights and the horn do not operate through the answerback function.

Horn Drive Circuit Part 1:

Horn Drive Circuit Part 2:

CIRCUIT OPERATION
The ETACS-ECU operates the following functions when it receives lock or unlock signal from the transmitter:
- Dome light answerback function
- Turn-signal light answerback function
- Horn answerback function

TECHNICAL DESCRIPTION (COMMENT)
The turn-signal lights and horn answerback functions can be disabled or enabled. However, the dome light answerback function can not be disabled.

TROUBLESHOOTING HINTS
- The turn-signal light may be defective
- The dome light may be defective
- The horn 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

STEP 1. Verify the keyless entry system.

Q: Does the keyless entry system work normally?

YES: Go to Step 2.

NO: Refer to Inspection Procedure E-1 "Keyless entry system does not work normally."

STEP 2. Check the configuration function.

Q: Has the answerback function been enabled by means of the adjustment function?

YES: Go to Step 3.

NO: Enable the answerback function by means of the adjustment function. Verify that the answerback functions work normally.

STEP 3. Verify trouble symptom.

Q: Which answerback function is defective?

Only the dome light : Go to Step 4.

Only the turn-signal lights : Go to Step 5.

Only the horn : Go to Step 6.

None of the dome light and the turn-signal lights and the horn : Replace the ETACS-ECU. Verify that the answerback functions work normally.

STEP 4. Verify the dome light.

Q: Does the dome light illuminate normally?

YES: Replace the ETACS-ECU. Verify that the answerback functions work normally.

NO: Refer to Inspection Procedure M-1 "Front dome light, rear dome light and luggage compartment light do not illuminate or go out normally."

STEP 5. Verify the hazard warning light.

Q: Does the hazard warning light work normally?

YES: Replace the ETACS-ECU. Verify that the answerback functions work normally.

NO: Refer to Inspection Procedure L-2 "Hazard warning lights do not flash when the hazard warning light switch is turned on."

STEP 6. Verify the horn operation.

Q: Does the horn work normally?

YES: Go to Step 21.

NO: Go to Step 7.

STEP 7. Verify which horn is defective.

Q: Which horn does not sound?

horn (HIGH) : Go to Step 8.

horn (LOW) : Go to Step 12.

horn (HIGH or LOW) : Go to Step 17.




STEP 8. Check horn (HIGH) connector A-18 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is horn (HIGH) connector A-18 in good condition?

YES: Go to Step 9.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Verify that the horn sounds normally.




STEP 9. Check the horn.
Connect the battery as shown, and Verify that the horn sounds.

Q: Is the horn normal?

YES: Go to Step 10.

NO: Replace the horn. Verify that the horn sounds normally.




STEP 10. Check horn relay connector A-05X for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is horn relay connector A-05X in good condition?

YES: Go to Step 11.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Verify that the horn sounds normally.







STEP 11. Check the wiring harness between horn relay connector A-05X (terminal 1) and horn (HIGH) connector A-18 (terminal 1).

Q: Is the wiring harness between horn relay connector A-05X (terminal 1) and horn (HIGH) connector A-18 (terminal 1) in good condition?

YES: Go to Step 16.

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. Verify that the horn sounds normally.




STEP 12. Check horn (LOW) connector A-19 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is horn (LOW) connector A-19 in good condition?

YES: Go to Step 13.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Verify that the horn sounds normally.




STEP 13. Check the horn.
Connect the battery as shown, and Verify that the horn sounds.

Q: Is the horn normal?

YES: Go to Step 14.

NO: Replace the horn. Verify that the horn sounds normally.




STEP 14. Check horn relay connector A-05X for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is horn relay connector A-05X in good condition?

YES: Go to Step 15.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Verify that the horn sounds normally.







STEP 15. Check the wiring harness between horn relay connector A-05X (terminal 1) and horn (LOW) connector A-19 (terminal 1).

Q: Is the wiring harness between horn relay connector A-05X (terminal 1) and horn (LOW) connector A-19 (terminal 1) in good condition?

YES: Go to Step 16.

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. Verify that the horn sounds normally.

STEP 16. Check the fit of the horn.
When the theft-alarm system is triggered, check the fit of the horn (HIGH or LOW) which does not sound.

NOTE: The horn is grounded to the vehicle body via its mounting bolt.

Q: Is the horn installed correctly.

YES: No action is necessary and testing is complete.

NO: Install the horn correctly. Verify that the horn sounds normally.




STEP 17. Check horn relay connector A-05X for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are horn relay connector A-05X in good condition?

YES: Go to Step 18.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Verify that the horn sounds normally.







STEP 18. Check the horn relay.

Q: Is the horn relay normal?

YES: Go to Step 19.

NO: Replace the horn relay. Verify that the horn sounds normally.

STEP 19. Check the battery power supply circuit to the horn relay. Test at horn relay connector A-05X.




1. Disconnect horn relay connector A-05X and measure the voltage available at the relay box side of the connector.




2. Measure the voltage between terminal numbers 2, 4 and ground.
- The voltage should equal approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts (battery positive voltage)?

YES: No action is necessary and testing is complete.

NO: Go to Step 20.




STEP 20. Check the wiring harness between horn relay connector A-05X (terminal 2 and 4) and the battery.

Q: Is the wiring harness between horn relay connector A-05X (terminal 2 and 4) and the battery 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. Verify that the horn sounds normally.







STEP 21. Check rear horn relay connector A-05X and ETACS-ECU connector C-227 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are horn relay connector A-05X and ETACS-ECU connector C-227 in good condition?

YES: Go to Step 22.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Verify that the horn sounds normally.










STEP 22. Check the wiring harness between horn relay connector A-05X (terminal 3) and ETACS-ECU connector C-227 (terminal 44).

NOTE: Also check intermediate connector C-129 and joint connector C-101 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-129 or joint connector C-101 is damaged, repair or replace the damaged component(s) as described in Harness Connector Inspection.

Q: Is the wiring harness between horn relay connector A-05X (terminal 3) and ETACS-ECU connector C-227 (terminal 44) in good condition?

YES: Replace the ETACS-ECU. Verify that the horn sounds 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. Verify that the horn sounds normally.