Inspection Procedure J-1
Headlight, taillight: Taillights do not illuminate.Taillight Relay Drive Circuit:
CIRCUIT OPERATION
The front-ECU illuminates the taillights if the column switch sends the taillight ON signal to the front-ECU.
TECHNICAL DESCRIPTION (COMMENT)
The taillight relay, column switch or the front-ECU may be defective.
NOTE: If only one light does not illuminate, the harness wire between the light and the taillight relay may be defective or the light bulb may be burned out. In this case, check the circuit by referring to Taillight, Position Light and License Plate Light.
TROUBLESHOOTING HINTS
- Malfunction of the column switch
- Malfunction of the column switch (turn-signal light and lighting switch)
- Malfunction of the front-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 DTC.
Q: Does DTC set when the ignition switch is turned to the "LOCK" (OFF) position?
YES: Carry out the troubleshooting by referring to Diagnostic Trouble Code Chart.
NO: Go to Step 2
STEP 2. Check the input signal (by using scan tool MB991502).
Check the input signal from the taillight switch.
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: Go to Step 4.
NO: Check the taillight switch input signal circuit. Refer to Inspection Procedure O-15.
STEP 3. Check the input signal (by using a voltmeter).
Check the input signal from the taillight switch.
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: Go to Step 4.
NO: Check the taillight switch input signal circuit. Refer to Inspection Procedure O-15.
STEP 4. Check the taillight relay.
Q: Is the taillight relay in good condition?
YES: Go to Step 5.
NO: Replace it. The taillights should illuminate normally.
STEP 5. Check the taillight relay power supply circuit at the taillight relay connector A-05X.
1. Disconnect the taillight relay connector A-05X and measure at the relay box side.
2. Measure the voltages between terminal 3, 4 and ground.
Q: Are the voltages approximately 12 volts (battery positive voltage)?
YES: Go to Step 8.
NO: Go to Step 6.
STEP 6. Check taillight relay connector A-05X for damage.
Q: Is taillight relay connector A-05X in good condition?
YES: Go to Step 7.
NO: Repair or replace it. Refer to Harness Connector Inspection. The taillights should illuminate normally.
STEP 7. Check the harness wire between taillight relay connector A-05X and battery.
Q: Is the harness wire between taillight relay connector A-05X and battery in good condition?
YES: There is no action to be taken.
NO: Repair it. The taillights should illuminate normally.
STEP 8. Check taillight relay connector A-05X and front-ECU connector A-09X for damage.
Q: Are taillight relay connector A-05X and front-ECU connector A-09X in good condition?
YES: Go to Step 9.
NO: Repair or replace them. Refer to Harness Connector Inspection. The taillights should illuminate normally.
STEP 9. Check the harness wire between taillight relay connector A-05X and front-ECU connector A-09X.
Q: Is the harness wire between taillight relay connector A-05X and front-ECU connector A-09X in good condition?
YES: Replace the front-ECU. The taillights should illuminate normally
NO: Repair it. The taillights should illuminate normally.