C1000

DTC C1000: Abnormality in stop light switch circuit





CAUTION
If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.

CIRCUIT OPERATION
ETACS-ECU sends the ON signal generated when the brake pedal is depressed and OFF signal generated when it is released to ABS-ECU via the CAN bus lines.

DTC SET CONDITIONS
This diagnostic trouble code is set in the following case.
^ When the vehicle has run for a long time with the stop light switch turned ON.
^ When there is difference between the stop light switch state and the vehicle's behavior

PROBABLE CAUSES
^ Improper adjustment of stop light switch installation position
^ Malfunction of the stop light switch
^ Damaged wiring harness and connectors
^ Malfunction of ETACS-ECU
^ ABS-ECU malfunction

DIAGNOSIS

Required Special Tools:
^ MB991958: Scan Tool (M.U.T-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827: M.U.T.-III USB Cable
^ MB991910: M.U.T.-III Main Harness A
^ MB991974: ABS check harness

STEP 1. M.U.T.-III CAN bus diagnostics
Use scan tool to diagnose the CAN bus lines.
Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. On completion, go to Step 2.

STEP 2. Diagnostic trouble code recheck after resetting CAN bus lines
Q: Is DTC C1000 set?
YES: Go to Step 3.
NO: The procedure is complete.

STEP 3. Stop light operation check
1) Turn the ignition switch to the ON position.
2) Check the stop light operation when the brake pedal is depressed. Check that the stop light illuminates when the brake pedal is depressed and that it goes out when the brake pedal is released.
OK:
When the brake pedal is released: OFF
When the brake pedal is depressed: ON

Q: Is the check result normal?
YES: Go to Step 10.
NO: Go to Step 4.

STEP 4. Check stop light switch installation
Q: Is the check result normal?
YES: Go to Step 5.
NO: Install the stop light switch correctly.

STEP 5. Stop light switch continuity check
1) Remove the stop light switch.





2) Connect the circuit tester (Ohm range) to the stop light switch connector terminals No. 1 and 2.
3) When no continuity is detected with the plunger pressed from the edge of the outer case by the dimension shown in the figure and when continuity is detected with the plunger released, the stop light switch is in good condition.

Q: Is the check result normal?
YES: Go to Step 6.
NO: Replace the stop light switch.

STEP 6. Check any other diagnostic trouble code is set.
Check if stop light-related DTC is set.
Q: Is the check result normal?
YES: Go to Step 7.
NO: Carry out the relevant diagnosis for the set DTC.

STEP 7. Voltage measurement at C-304 ETACS-ECU connector
1) Turn the ignition switch to the ON position.
2) Measure the voltage between terminal No. 1 and body ground.
OK: Approximately battery voltage

Q: Is the check result normal?
YES: Go to Step 8.
NO: Go to Step 9.

STEP 8. Connector check: C-304 ETACS-ECU connector, C-32 stop light switch connector
Q: Is the check result normal?
YES: The short circuit between the C-304 ETACS-ECU connector terminal No. 1 and the C-32 stop light switch connector terminal No.2 may be present. Repair the wiring harness between the C-304 ETACS-ECU connector terminal No. 1 and the C-32 stop light switch connector terminal No.2.
NO: Repair the defective connector.

STEP 9. ETACS-ECU fuse No.2 check
Q: Is the check result normal?
YES: Replace the ETACS-ECU, and then go to Step 12.
NO: Replace the fuse No.2.

STEP 10. Voltage measurement at C-312 ETACS-ECU connector
1) Turn the ignition switch to the ON position.

CAUTION
Do not depress the brake pedal.

2) Measure the voltage between terminal No. 16 and body ground.

OK: Approximately 5 volts

Q: Is the check result normal?
YES: Go to Step 11.
NO: Replace the ETACS-ECU, and then go to Step 12.

STEP 11. Connector check: C-312 ETACS-ECU connector, C-32 stop light switch connector
Q: Is the check result normal?
YES: The short circuit between the C-312 ETACS-ECU connector terminal No. 16 and the C-32 stop light switch connector terminal No. 1 may be present. Repair the wiring harness between the C-312 ETACS-ECU connector terminal No. 16 and the C-32 stop light switch connector terminal No. 1.
NO: Repair the defective connector.

STEP 12. Check whether the diagnostic trouble code is reset.
Q: Is DTC 1000 set?
YES: Replace the ABS-ECU.
NO: The procedure is complete.