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Inspection Procedure E-2

Horn Circuit <2000 Models Without Theft-alarm System:




Connectors:






CIRCUIT OPERATION
The ETACS-ECU operates the horns through the keyless entry system answerback if the requirements for the horns are satisfied.

TECHNICAL DESCRIPTION (COMMENT)
The turn-signal light and the horn answerback functions can be selected by the driver's desire (can be deactivated). However, the dome light answerback function can not be deactivated. If all of these devices do not operate through the answerback function, the ETACS-ECU may be defective.

NOTE: Horn answerback function is applicable to only 2000 models.

TROUBLESHOOTING HINTS
- Malfunction of the turn-signal light
- Malfunction of the horn
- Malfunction of the horn relay
- Malfunction of the dome light
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors

DIAGNOSIS
Required Special Tools:
MB991223: Test Harness Set
MB991502: Scan Tool (MUT-II)
MB991529: Diagnostic Trouble Code Check Harness

STEP 1. Check the answerback set condition.
Activate the answerback functions. (Refer to Keyless Entry System - On-vehicle Service - Enabling/disabling the Answerback Function.)

The answerback function should work normally.

When the answerback does not work normally although the answerback function is activated, go to Step 2.

STEP 2. Check trouble symptom.
If only the dome light does not operate through the answerback, go to Step 3.

If only the hazard warning lights do not operate through the answerback, go to Step 4.

For vehicles with theft-alarm system, if only the horn does not operate through the answerback, go to Step 5.

For vehicles without theft-alarm system, if only the horn does not operate through the answerback, go to Step 6.

If none of the dome light, the hazard warning lights, and the horn operates through the answerback, replace the ETACS-ECU.

The answerback function should work normally.

STEP 3. Check the dome light operation.
If the dome light does not operate through the answerback, check the dome light dimming function. If the dimming function is defective, carry out the dome light troubleshooting.

If the dome light operates normally, replace the ETACS-ECU.

The answerback function should work normally.

STEP 4. Check the hazard warning light operation.
If the hazard warning lights do not operate through the answerback, check that the hazard warning lights flash by using the hazard warning light switch. If the hazard warning lights do not flash, follow the hazard warning light troubleshooting. Refer to Inspection Procedure J-2.

If the hazard warning lights flash normally, replace the ETACS-ECU.

The answerback function should work normally.

STEP 5. Check the theft-alarm horn operation.
If the theft-alarm horn does not operate through the answerback, check whether the theft-alarm system triggers the theft-alarm horn. If no, troubleshoot the theft-alarm system.

If yes, replace the ETACS-ECU.

The answerback function should work normally.




STEP 6. Check the horn.
Connect the battery as shown and check that the horn sounds.

If the horn is damaged, replace it.

The answerback function should work normally.

If the horn is not damaged, go to Step 7.







STEP 7. Check the horn relay.
If the horn relay is damaged, replace it.

The answerback function should work normally.

If the horn relay is not damaged, go to Step 8.




STEP 8. Check the horn relay power supply circuit at the horn relay connector A-15X.
1. Disconnect the relay connector A-15X and measure at the relay box side.
2. Voltage between terminal 4 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).

3. Voltage between terminal 3 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).
If one of the checks above does not show approximately 12 volts, go to Step 9.
If both of the checks above show approximately 12 volts, go to Step 11.




STEP 9. Check the horn relay connector A-15X for damage.
If the horn relay connector A-15X is damaged, repair or replace it. Refer to Harness Connector Inspection.

The answerback function should work normally.

If the connector is in good condition, go to Step 10.
















STEP 10. Check the harness wires between horn relay connector A-15X and fusible link (1).

NOTE: After checking junction block connectors C-85 and C-77 and intermediate connector C-66, check the wires. If junction block connectors C-85 and C-77 and intermediate connector C-66 are damaged, repair or replace them. Refer to Harness Connector Inspection.

If the harness wires between horn relay connector A-15X and fusible link (1) are damaged, repair them.

The answerback function should work normally.







STEP 11. Check the horn relay connector A-15X and ETACS-ECU connector C-81 for damage.
If the horn relay connector A-15X and ETACS-ECU connector C-81 are damaged, repair or replace them. Refer to Harness Connector Inspection.

The answerback function should work normally.

If the connectors are in good condition, go to Step 12.










STEP 12. Check the harness wires between horn relay connector A-15X and ETACS-ECU connector C-81.

NOTE: After checking intermediate connector C-66, check the wires. If intermediate connector C-66 is damaged, repair or replace them. Refer to Harness Connector Inspection.

If the harness wires between horn relay connector A-15X and ETACS-ECU connector C-81 are damaged, repair them.

The answerback function should work normally.

If the harness wires are in good condition, go to Step 13.







STEP 13. Check the horn relay connector A-15X and horn connector A-29 for damage.
If the theft-alarm horn relay connector A-15X and horn connector A-29 are damaged, repair or replace them. Refer to Harness Connector Inspection.

The answerback function should work normally.

If the connectors are in good condition, go to Step 14.







STEP 14. Check the harness wire between horn relay connector A-15X and horn connector A-29.
If the harness wire between horn relay connector A-15X and horn connector A-29 is damaged, repair it.

The answerback function should work normally.

If the harness wire is in good condition, go to Step 15.

STEP 15. Check the horn installation state.

NOTE: The horn is grounded to the body through the installation bolts.

If the horn installation state is not in good condition, repair it. The answerback function should work normally.

If it is in good condition, replace the ETACS-ECU.

The answerback function should work normally.
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