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Inspection Procedure 2: The stoplights do not illuminate or go out normally.
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the stoplights do not illuminate or go out normally, the stoplight switch input signal circuit, or the stoplights may be defective.
 
 
TROUBLESHOOTING HINTS
  • The stoplight switch input signal circuit may be defective
  • The rear combination light assembly may be defective
  • The high-mounted stoplight 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:
  • MB992006: Extra fine probe
  • MB991223: Harness set
STEP 1. Using scan tool (M.U.T.-IIISE), check data list.
Check the ETACS-ECU data list.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect Scan Tool (M.U.T.-IIISE) ."
(2) Check the signals related to the stoplight illumination.
  • Depress the brake pedal.
 
Item No.Item nameNormal condition
113Stoplight switchON
OK: Normal condition is displayed.
Is the check result normal?
Go to Step 2.
Troubleshoot the ETACS-ECU (Refer to Inspection Procedure 12 "The stoplight switch signal is not received." ).
 
STEP 2. Resistance measurement at the stoplight connectors (ground terminals).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the rear combination light (LH) connector (ground terminal) and body ground.
OK: The resistance should be 2 ohms or less
(3) Measure the resistance between the rear combination light (RH) connector (ground terminal) and body ground.
OK: The resistance should be 2 ohms or less
(4) Measure the resistance between the high-mounted stoplight connector (ground terminal) and body ground.
OK: The resistance should be 2 ohms or less
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 ).
Go to Step 3.
 
STEP 3. Check of open circuit in ground line between the rear combination light (LH) connector, rear combination light (RH) connector, high-mounted stoplight connector and body ground.
Is the check result normal?
Go to Step 4.
Repair the connector(s) or wiring harness.
 
STEP 4. Voltage measurement at stoplight connectors (power supply terminals).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Stoplight switch: ON.
(3) Check the voltage between the rear combination light (LH) connector (power supply terminal) and body ground.
OK: Is the measured voltage approximately 12 volts (battery positive voltage)
(4) Check the voltage between the rear combination light (RH) connector (power supply terminal) and body ground.
OK: Is the measured voltage approximately 12 volts (battery positive voltage)
(5) Check the voltage between the high-mounted stoplight connector (power supply terminal) and body ground.
OK: Is the measured voltage approximately 12 volts (battery positive voltage)
Is the check result normal?
Go to Step 6.
Go to Step 5.
 
STEP 5. Check of short to power supply, short to ground, and open circuit in STLO line between ETACS-ECU connector and rear combination light (LH) connector, rear combination light (RH) connector, high-mounted stoplight connector.
Is the check result normal?
Go to Step 6.
Repair the connector(s) or wiring harness.
 
STEP 6. 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 unit or high-mounted stoplight.