DTC 38

DTC 38 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 18).

ABS DTC SET CONDITION
Output is provided in the following cases.
- Stoplight switch is in trouble and remains in ON state for more than 15 minutes.
- Stoplight switch system harness is broken and no signal is input to ABS-ECU.

TROUBLESHOOTING HINTS
The most likely causes for DTC is 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 Tool: MB991223: Harness Set
STEP 1. Check the stoplight operation.
If the stoplight does not light, go to Step 2.
If the stoplight correctly lights and goes out, go to Step 3.
STEP 2. Check the stoplight switch installation condition.
If the stoplight switch installation condition is not good, repair it. Then go to Step 7.
If the stoplight switch installation condition is good, go to Step 4.





STEP 3. Check the stoplight switch circuit at the ABS-ECU connector A-03.
1. Disconnect connector A-03 and measure at the harness side.
2. Turn the stoplight switch "ON."
3. Measure the voltage between terminal 18 and ground. Voltage should be approximately 12 volts (battery positive voltage)
If not approximately 12 volts, go to Step 5.
If approximately 12 volts, replace the hydraulic unit (integrated with ABS-ECU). Then go to Step 7.
STEP 4. Check the stoplight switch continuity.
1. Remove the stoplight switch.





2. Connect an ohmmeter to the stoplight switch terminal 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 (0.2 inch) from the outer case edge surface, and if there is continuity when it is released.
If the stoplight switch is damaged, replace it. Then go to Step 7.
If the stoplight switch is not damaged, go to Step 6.








STEP 5. Check the harness wire between ABS-ECU connector A-03 and intermediate connector C-66.
If any harness wire between ABS-ECU connector A-03 and intermediate connector C-66 is damaged, repair it. Then go to Step 7.











NOTE: After inspecting intermediate connector C-13, C-57, or C-71, inspect the wire. If intermediate connector C-13, C-57 or C-71 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 7.





STEP 6. Check the harness wire between fusible link number 1 and stoplight switch connector C-03.
If any harness wire between fusible link number 1 and stoplight switch connector C-03 is damaged, repair it. Then go to Step 7.











NOTE: After inspecting intermediate connector C-66, C-77, or C-85, inspect the wire. If intermediate connector C-66, C-77 or C-85 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 7.

STEP 7. Check the diagnostic trouble codes.
Confirm that diagnostic trouble code 38 does not reset.