DTC 33

DTC 33: Stoplight Switch System









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 hydraulic unit (integrated with ABS-ECU)

DIAGNOSIS
Required Special Tools:
^ MB991223: Harness Set
^ MB991958: Scan Tool (MUT-III Sub Assembly)
^ MB991824: Vehicle Communication Interface
^ MB991827: MUT-III USB Cable
^ MB991910: MUT-III Main Harness A
^ MB991529: Diagnostic Trouble Code Check Harness

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 MB991958, check data list.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the LOCK (OFF) position before connecting or disconnecting scan tool MB991958.





1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the ON position.
3. Set scan tool MB991958 to data reading mode.
^ 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-03.





1. Disconnect connector B-03 and measure at the harness side.
2. Turn the stoplight switch ON.
3. Measure the voltage between terminal 3 and ground. It should be battery positive voltage (approximately 12 volts) present.
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Erase the DTC memory, and recheck if any DTC sets. If DTC 33 set, replace the hydraulic unit (integrated with ABS-ECU). Then go to Step 7.
NO: Go to Step 6.

STEP 6. Check the harness wire between ABS-ECU connector B-03 terminal 3 and stoplight switch connector C-101 terminal 1.











NOTE: After inspecting intermediate connectors C-16, C-104 and stoplight switch connector C-101, inspect the wire. If intermediate connectors C-16, C-104 and stoplight switch connector C-101 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-03 terminal 3 and stoplight switch connector C-101 terminal 1 damaged?
YES: Repair it and then go to Step 7.
NO: Go to Step 7.

STEP 7. Recheck for diagnostic trouble codes.
Q: Does DTC 33 reset?
YES: Return to Step 1.
NO: The procedure is complete.