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Inspection Procedure 4: The stoplight do not illuminate or go out normally.
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the stoplights do not illuminate or go out normally, the stoplight switch input circuit, ground circuit system, stoplight switch may be defective.
 
 
TROUBLESHOOTING HINTS
  • The stoplight switch may be faulty.
  • The stoplight switch input circuit may be faulty.
  • The stoplights may be faulty.
  • The rear combination light assembly may be faulty.
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector.
 
 
DIAGNOSIS
Required Special Tools:
  • MB992006: Extra fine probe
  • MB991223: Harness set
STEP 1. Using scan tool (M.U.T.-III), check data list.
(1)
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Connect scan tool (M.U.T.-III). Refer to "How to connect Scan Tool (M.U.T.-III) ."
(2) Check the ETACS-ECU input signals from the stoplight switch.
  • Brake pedal: depressed
 
Item No.Item nameNormal condition
108Stoplight switchOFF to ON (only when switch is operated)
OK: Normal condition is displayed.
Is the check result normal?
Go to Step 2.
Troubleshoot the ETACS-ECU. Refer to ETACS, Diagnosis .
 
STEP 2. Voltage measurement at the joint connector.
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Stoplight switch: ON
(3) Measure the voltage between the joint connector (power supply terminal) and the ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 4.
Go to Step 3.
 
STEP 3. Check of short to power supply, and open circuit in power supply line between the joint connector and the fusible link.
Is the check result normal?
Go to Step 5.
Repair the connector(s) or wiring harness.
 
STEP 4. Resistance measurement at the high-mounted stoplight connector, rear combination light (stoplight: LH) connector, rear combination light (stoplight: RH) connector.
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the connector of light which does not illuminate and the ground.
  • Measure the resistance between the high-mounted stoplight connector (ground terminal) and the ground.
  • Measure the resistance between the rear combination light (stoplight: LH) connector (ground terminal) and the ground.
  • Measure the resistance between the rear combination light (stoplight: RH) connector (ground terminal) and the ground.
OK: The resistance should be 2 ohms or less.
Is the check result normal?
Go to Step 6.
Go to Step 5.
 
STEP 5. Check the following wiring harness.
Check the wiring harness for ground circuit between the following connectors:
  • Check of open circuit in ground line between high-mounted stoplight connector and ground.
  • Check of open circuit in ground line between rear combination light (stoplight: LH) connector and ground.
  • Check of open circuit in ground line between rear combination light (stoplight: RH) connector and ground.
Is the check result normal?
Go to Step 6.
Repair the connector(s) or wiring harness.
 
STEP 6. Check the following wiring harness.
Check the wiring harness for open circuit between the following connectors:
  • Check of open circuit in output line between high-mounted stoplight connector and joint connector.
  • Check of open circuit in output line between rear combination light (stoplight: LH) connector and joint connector.
  • Check of open circuit in output line between rear combination light (stoplight: RH) connector and joint connector.
Is the check result normal?
Go to Step 7.
Replace the connector(s) or wiring harness.
 
STEP 7. Retest the system.
Check that the stoplights illuminates normally.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the rear combination light assembly or the stoplights.