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Inspection Procedure 10: The stoplight switch signal is not received.
 
 
cautionWhenever the ECU is replaced, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TECHNICAL DESCRIPTION (COMMENT)
If there is an error to the stoplight switch input signal, the stoplight switch signal is no longer output to the communication line.
 
 
TROUBLESHOOTING HINTS
  • The stoplight switch may be defective
  • The ETACS-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: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check the stoplight switch.
Refer to GROUP 35A - Brake Pedal .
Is the check result normal?
Go to Step 2.
Replace the stoplight switch.
 
STEP 2. Voltage measurement at stoplight switch connector (power supply terminal)
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Check the voltage between the stoplight switch connector (power supply terminal) and 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, short to ground, and open circuit in power supply line between stoplight switch connector and fusible link
Is the check result normal?
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Repair the connector(s) or wiring harness.
 
STEP 4. Check of short to power supply, short to ground, and open circuit in BKLP line between ETACS-ECU connector and stoplight switch connector
Is the check result normal?
Go to Step 5.
Repair the connector(s) or wiring harness.
 
STEP 5. 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 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?
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 ETACS-ECU.