Inspection Procedure J-1
INSPECTION PROCEDURE J-1: Headlight, Taillight: Taillights do not illuminate.Tailight Relay Circuit:
Connectors:
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 column switch or the front-ECU may be defective.
NOTE: If only one light does not illuminate, the wiring harness between the light and the front-ECU 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
- The column switch (turn-signal light and lighting switch) may be defective
- The front-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: 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: Scan tool MB991502 does not sound when the lighting switch is turned from "OFF" to "TAIL": Refer to Inspection Procedure O-14 "The taillight switch signal is not sent to the ETACS-ECU." Inspection Procedure O-14
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: The voltmeter needle does not fluctuate when the lighting switch is turned from "OFF" to "TAIL": Refer to Inspection Procedure O-14 "The taillight switch signal is not sent to the ETACS-ECU." Inspection Procedure O-14
STEP 4. Check the power supply circuit to the front-ECU. Test at front-ECU connector A-10X.
1. Disconnect front-ECU connector A-10X and measure the voltage available at the relay box side of the connector.
2. Measure the voltage between terminal 5 and ground.
- The voltage should equal approximately 12 volts (battery positive voltage).
Q: Is the measured voltage approximately 12 volts (battery positive voltage)?
YES: Replace the front-ECU. Check that the tail lights illuminate normally.
NO: Go to Step 5.
STEP 5. Check the front-ECU connector A-10X for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is front-ECU connector A-10X in good condition?
YES: Go to Step 6.
NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Harness Connector Inspection The taillights should illuminate normally.
STEP 6. Check the wiring harness between front-ECU connector A-10X (terminal 5) and battery.
Q: Is the wiring harness between front-ECU connector A-10X (terminal 5) and 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. The taillights should illuminate normally.