Inspection Procedure E-1

Keyless entry system: Keyless entry system does not operate.

Receiver And Transmitter Communication Circuit:

CIRCUIT OPERATION
Receiver within the ETACS-ECU receives the lock/unlock signal from the transmitter.

TECHNICAL DESCRIPTION (COMMENT)
The cause may be a malfunction of the receiver and transmitter communication system.

TROUBLESHOOTING HINTS
- Malfunction of the ETACS-ECU
- Malfunction of the transmitter

DIAGNOSIS

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

STEP 1. Check the central door locking system operation.

Q: Does the central door locking system work normally?

YES: Go to Step 2 or 3 .
NO: Solve the problem first.

STEP 2. Check the input signal (by using scan tool MB991502).
Check the input signals from the transmitter switches.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Check that the tone alarm of scan tool MB991502 sounds when the input signal enters.

Q: Does the tone alarm of scan tool MB991502 sound when the input signal enters?

YES: Replace the ETACS-ECU. All the doors should be locked or unlocked by using the transmitter.
NO: Check the transmitter input circuit. Refer to Inspection Procedure O-18.

STEP 3. Check the input signal (by using a voltmeter).
Check the input signals from the transmitter switches.

1. Use special tool MB991529 to connect a voltmeter between ground terminal 4 or 5 and ETACS-ECU terminal 9 of the data link connector.
2. Check that the voltmeter indicator deflects once when the input signal enters.

Q: Does the voltmeter indicator deflect?

YES: Replace the ETACS-ECU. All the doors should be locked or unlocked by using the transmitter.
NO: Check the transmitter input circuit. Refer to Inspection Procedure O-18.