Brake Warning Light Circuit

BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM: Brake Warning Light Circuit

Brake Warning Light Circuit

DESCRIPTION

The brake warning light illuminates when the brake fluid is insufficient, the parking brake is applied or the EBD is defective.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK FOR DTC
(a) Turn the ignition switch ON.
(b) Check that the ABS warning light turns on.
(c) Check for DTC Reading and Clearing Diagnostic Trouble Codes.

Result





B -- REPAIR CIRCUITS INDICATED BY OUTPUT DTCS
A -- Continue to next step.
2. PERFORM ACTIVE TEST USING TECHSTREAM (BRAKE WARNING LIGHT)
(a) Using the Techstream Active Test, generate a control command and then check that the brake warning light operates.

ABS/VSC/TRAC





OK:
Brake warning light is turned on or off in accordance with the Techstream.
OK -- REPLACE SKID CONTROL ECU
NG -- Continue to next step.
3. INSPECT PARKING BRAKE SWITCH




(a) Remove the parking brake switch.
(b) Measure the resistance of the switch.
Standard resistance:






NG -- REPLACE PARKING BRAKE SWITCH
OK -- Continue to next step.
4. INSPECT BRAKE FLUID LEVEL WARNING SWITCH




(a) Remove the reservoir tank cap and strainer.
(b) Disconnect the B4 switch connector.
(c) Measure the resistance of the switch.
Standard resistance:






NG -- REPLACE BRAKE ACTUATOR
OK -- Continue to next step.
5. CHECK WIRE HARNESS (SKID CONTROL ECU - PARKING BRAKE SWITCH)




(a) Disconnect the S6 ECU connector.
(b) Disconnect the P3 switch connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.
6. CHECK WIRE HARNESS (BRAKE FLUID LEVEL WARNING SWITCH - SKID CONTROL ECU AND BODY GROUND)




(a) Disconnect the B4 switch connector.
(b) Disconnect the S5 ECU connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.
7. CHECK MULTIPLEX COMMUNICATION SYSTEM (SKID CONTROL ECU - COMBINATION METER)
(a) Check for open and short circuits in the multiplex communication system between the skid control ECU and combination meter.
NG -- REPAIR OR REPLACE MULTIPLEX COMMUNICATION SYSTEM
OK -- Continue to next step.
8. CHECK COMBINATION METER (BRAKE WARNING LIGHT)
(a) Check the combination meter Problem Symptoms Table.
NG -- REPAIR OR REPLACE COMBINATION METER
OK -- REPLACE SKID CONTROL ECU