Inspection Procedure 2
Stoplight Switch Circuit:
Connectors:
CIRCUIT OPERATION
This is the stoplight switch input signal circuit. The signal is sent to the stoplight switch from multi-purpose fuse 8, and is then sent to the auto-cruise
control-ECU.
TECHNICAL DESCRIPTION (COMMENT)
The cause is probably a malfunction of the stoplight switch circuit.
TROUBLESHOOTING HINTS
- Malfunction of the stoplight switch.
- Damaged harness or connector.
- Malfunction of the auto-cruise control-ECU.
DIAGNOSIS
Required Special Tool:
- MB991223: Harness Set
STEP 1.Check if the stoplight illuminates.
Q: Is the stoplight illuminated?
YES: Go to Step 7.
NO: Go to Step 2.
STEP 2.Check the 12-Volt supply circuit voltage at stoplight switch connector C-66.
1. Disconnect stoplight switch connector C-66 and measure at the harness side.
2. Measure the voltage between terminal 2 and ground.
Q: Is the voltage approximately battery positive voltage?
YES: Go to Step 6.
NO: Go to Step 3.
STEP 3.Check stoplight switch connector C-66.
Q: Is the connector damaged?
YES: Repair or replace connector.
Refer to Harness Connector Inspection.
Then check that the malfunction is eliminated.
NO: Go to Step 4.
STEP 4.Check junction connector D-02 and D-09.
Q: Is any connectors damaged?
YES: Repair or replace connector.
Refer to Harness Connector Inspection.
Then check that the malfunction is eliminated.
NO: Go to Step 5.
STEP 5.Check the harness wire between fusible link No.6 and stoplight switch connector C-66.
Q: Is any harness wire between fusible link No.6 and stoplight switch connector C-66 damaged?
YES: Repair the harness wire and then check that the malfunction is eliminated.
NO: Check that the malfunction is eliminated.
If the malfunction is eliminated, replace the auto-cruise control-ECU.
Then check that the malfunction is eliminated.
STEP 6.Check the stoplight switch.
1. Disconnect harness connector C-66 at the stoplight switch.
2. Connect an ohmmeter to the stoplight switch, and check continuity when the plunger of the stoplight switch is pushed in and when it is released.
3. The stoplight switch is in good condition if the circuit is open when the plunger is pushed in to a depth of within 4 mm (0.2 inch) from the outer case edge surface, and if the resistance value is less than 2 Ohms when it is released.
4. The check for continuity should be made at terminals 2 and 3 of the stoplight switch.
Q: Is the circuit open?
YES: Replace the stoplight switch.
Refer to Brake Pedal.
Then check that the malfunction is eliminated.
NO: Go to Step 7.
STEP 7.Check the output circuit voltage at auto-cruise control-ECU connector C-35 by backprobing.
1. Do not disconnect auto-cruise control-ECU connector C-35.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 4 and ground by backprobing.
- Voltage should be battery positive volts.
(When brake pedal is depressed.)
- Voltage should be 0.5 volts or less.
(When brake pedal is not depressed.)
4. Turn the ignition switch to "LOCK" (OFF) position.
Q: Is the voltage within specifications?
YES: Check that the malfunction is eliminated.
If the malfunction is eliminated, replace the auto-cruise control-ECU.
Then check that the malfunction is eliminated.
NO: Go to Step 8.
STEP 8.Check auto-cruise control-ECU connector C-35 and stoplight switch connector C-66.
Q: Is the connector damaged?
YES: Repair or replace connector.
Refer to Harness Connector Inspection.
Then check that the malfunction is eliminated.
NO: Go to Step 9.
STEP 9.Check the harness wire between stoplight switch connector C-66 and auto-cruise control-ECU connector C-35.
Q: Is any harness wire between stoplight switch connector C-66 and auto-cruise control-ECU connector C-35 damaged?
YES: Repair the harness wire and then check that the malfunction is eliminated.
NO: Check that the malfunction is eliminated.
If the malfunction is eliminated, replace the auto-cruise control-ECU.
Then check that the malfunction is eliminated.
NOTE: After checking intermediate connector C-10, inspect the wire. If any intermediate connector is damaged, repair or replace them. Refer to Harness Connector Inspection. Then check that the malfunction is eliminated.