DTC 38

DTC 33: Stoplight Switch System





Part 1 of 2





Part 2 of 2

CIRCUIT OPERATION
The "ON" signal when the brake pedal is pressed or the "OFF" signal when the brake pedal is released is input to the ABS-ECU (terminal 3).

ABS DTC SET CONDITION
DTC 33 is output in the following cases:
- Stoplight switch is not operating properly and remains in ON state for more than 15 minutes.
- Stoplight switch system harness is damaged and no signal is input to ABS-ECU.

TROUBLESHOOTING HINTS (The most likely causes for DTC 33 to set are:)
- Malfunction of the stoplight switch
- Damaged wiring harness and connector
- Malfunction of the ABS-ECU

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991502: Scan tool (MUT-II)

STEP 1. Check the stoplight operation.
Q: Does the stoplight come on and go out correctly?
YES: Go to Step 4.
NO: Go to Step 2.

STEP 2. Check the stoplight switch installation condition.
Q: Is the stoplight switch installed properly?
YES: Go to Step 3.
NO: Repair it and then go to Step 7.





STEP 3. Check the stoplight switch continuity.
1) Remove the stoplight switch.
2) Connect an ohmmeter to stoplight switch terminals 1 and 2, and check whether there is 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 there is no continuity when the plunger is pushed in to a depth of within 4 mm (0.16 inch) from the outer case edge surface, and if there is continuity when it is released.
Q: Is the stoplight switch continuity incorrect?
YES: Replace it and then go to Step 7.
NO: Check the stoplight circuit and repair and then go to Step 7.





STEP 4. Using scan tool MB991602, check data list item 33: Stoplight 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) Turn the ignition switch to the "ON" position.
3) Set scan tool MB991502 to data reading mode for item 33, Stoplight switch.
- ON with brake pedal stepped down.
- OFF with brake pedal released.
Q: Is the stoplight switch input normal?
YES: This malfunction is intermittent.
NO: Go to Step 5.





STEP 5. Check the stoplight switch circuit at ABS-ECU connector B-118
1) Disconnect connector B-118 and measure at the harness side.
2) Turn the stoplight switch ON.
3) Measure the voltage between terminal 3 and ground. It should be approximately 12 volts (battery positive voltage).
Q: Is the voltage approximately 12 volts?
YES: Replace the hydraulic unit (integrated with ABS-ECU) and then go to Step 7.
NO: Go to Step 6.











STEP 6. Check the harness wire between ABS-ECU connector B-118 and stoplight switch connector C-102.

NOTE: After inspecting intermediate connectors C-105, C-124, C-129 and stoplight switch connector C-102, inspect the wire. If intermediate connectors C-105, C-124, C-129 and stoplight switch connector C-102 are damaged, repair or replace them. If the connector has been repaired or replaced, go to Step 7.

Q: Is the harness wire between ABS-ECU connector B-118 and stoplight switch connector C-102 damaged?
YES: Repair it and then go to Step 7.
NO: Go to Step 7.

STEP 7. Check the DTC.
Q: Does DTC 33 reset?
YES: Return to Step 1.
NO: This diagnosis is complete.