Inspection Procedure 5: The brake warning lamp remains illuminated after the engine is started.
















OPERATION

  • The brake warning lamp illuminates or goes out by the transistor control inside the ASTC-ECU. In this circuit, when the transistor is ON, the brake warning lamp goes out. Even when the ASTC-ECU connector is connected improperly or the ASTC-ECU is disabled, the brake warning lamp illuminates by the circuit in the meter.
  • Other than the case when the system has malfunctioned, the ASTC-ECU illuminates the brake warning lamp for approximately 3 seconds during the initial check with the ignition switch being in the ON position.
  • The brake warning lamp illuminates also in the cases when the parking brake is operated, and when the brake fluid level is the specified value or less.

PROBABLE CAUSES
The most likely causes for this case are:

  • The brake pad thickness is at the limit value or less.
  • The brake fluid amount is at the "LOWER" level or lower.
  • Poor adjustment of the parking brake lever
  • Damaged wiring harness and connectors
  • Parking brake switch malfunction
  • Brake fluid level switch malfunction
  • Malfunction of the combination meter
  • The ASTC-ECU is defective.

DIAGNOSIS

STEP 1. Brake fluid level check
Check that the brake fluid is filled up to the "MIN" level or higher.

Q. Is the check result normal?
Go to Step 3.
Go to Step 2.

STEP 2. Brake pad check
Refer to GROUP 35A - On-vehicle Service, Brake Pad Check .

Q. Is the check result normal?
Fill the brake fluid up to the "MAX" level. Then go to Step 15.
Replace the brake pad. (Refer to GROUP 35A - On-vehicle Service, Disc Brake Pad Check and Replacement <short wheelbase>, <long wheelbase>.) Then go to Step 15.

STEP 3. Brake fluid level switch check
Refer to GROUP 35A - On-vehicle Service, Brake Fluid Level Switch Check .

Q. Is the check result normal?
Go to Step 4.
Replace the reservoir assembly. <Refer to GROUP 35A - Hydraulic Brake Booster Assembly (HBB) .> Then go to Step 15.

STEP 4. Connector check: B-11 Brake fluid level switch connector

Q. Is the check result normal?
Go to Step 5.
Repair the damaged connector.

STEP 5. Parking brake lever stroke check
Refer to GROUP 36 - On-vehicle Service .

Q. Is the check result normal?
Go to Step 6.
Adjust the parking brake lever stroke. (Refer to GROUP 36 - On-vehicle Service .) Then go to Step 15.

STEP 6. Parking brake switch check
Refer to GROUP 36 - On-vehicle Service .

Q. Is the check result normal?
Go to Step 7.
Replace the parking brake switch. (Refer to GROUP 36 - Parking Brake Lever .) Then go to Step 15.

STEP 7. Connector check: D-21 parking brake switch connector

Q. Is the check result normal?
Go to Step 8.
Repair the damaged connector.

STEP 8. Connector check: D-02 combination meter connector, D-227 intermediate connector, D-230 intermediate connector

Q. Is the check result normal?
Go to Step 9.
Repair the damaged connector.

STEP 9. Wiring harness check: Between D-21 parking brake switch connector and D-02 combination meter connector
Check the wiring harness between D-21 parking brake switch connector terminal No. 1 and D-02 combination meter connector terminal No. 37 for short circuit.

Q. Is the check result normal?
Go to Step 10.
Repair the wiring harness.

STEP 10. Wiring harness check: Between B-11 brake fluid level switch connector and D-02 combination meter connector
Check B-11 brake fluid level switch connector terminal No. 1 and D-02 combination meter connector terminal No. 37 for short circuit.

Q. Is the check result normal?
Go to Step 11.
Repair the wiring harness.

STEP 11. Connector check: D-223 ASTC-ECU connector

Q. Is the check result normal?
Go to Step 12.
Repair the damaged connector.

STEP 12. Wiring harness check: Between D-223 ASTC-ECU connector and D-02 combination meter connector
Check the wiring harness between D-223 ASTC-ECU connector terminal No. 81 and D-02 combination meter connector terminal No. 45 for short circuit.

Q. Is the check result normal?
Go to Step 13.
Repair the wiring harness.

STEP 13. Retest the system.

Q. After the ignition switch is turned to the "ON" position and the brake warning lamp has illuminated for 3 seconds, does the lamp go out?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .
Replace the combination meter assembly. (Refer to GROUP 54A - Combination Meter .) Then go to Step 14.

STEP 14. Retest the system.

Q. After the ignition switch is turned to the "ON" position and the brake warning lamp has illuminated for 3 seconds, does the lamp go out?
The procedure is complete.
Replace the ASTC-ECU, and then go to Step 15.

STEP 15. Retest the system.

Q. After the ignition switch is turned to the "ON" position and the brake warning lamp has illuminated for 3 seconds, does the lamp go out?
The procedure is complete.
Start over at Step 1.