ABS Warning Light Remains ON

BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM: ABS Warning Light Remains ON
- ABS Warning Light Remains ON

DESCRIPTION

If any of the following is detected, the ABS warning light remains on.

* The skid control ECU connectors are disconnected from the skid control ECU.

* There is a malfunction in the skid control ECU internal circuit.

* There is an open in the harness between the combination meter and skid control ECU.

* The anti-lock brake system is defective.

* The voltage at terminal IG1 is high.

* The rear differential is locked.*

*: w/ Rear Differential Lock

HINT
It may not be possible to use the Techstream when the skid control ECU is abnormal.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
* When replacing the master cylinder solenoid, perform calibration Programming and Relearning.
* Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1. CHECK THAT SKID CONTROL ECU CONNECTOR IS SECURELY CONNECTED

(a) Check the skid control ECU connector connection.

OK:

The connector is securely connected.

NG -- CONNECT CONNECTOR TO ECU CORRECTLY
OK -- Continue to next step.

2. CHECK DTC

(a) Check for DTCs Reading and Clearing Diagnostic Trouble Codes.

Result





B -- REPAIR CIRCUITS INDICATED BY OUTPUT DTCs Vehicle Stability Control System
A -- Continue to next step.

3. CHECK CAN COMMUNICATION LINE

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Turn the Techstream on.

(e) Select CAN Bus Check from the System Selection Menu screen and follow the prompts on the screen to inspect the CAN bus Diagnosis System.

OK:

CAN Bus Check indicates no malfunctions in CAN communication.

NG -- GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) How to Proceed With Troubleshooting
OK -- Continue to next step.

4. READ VALUE USING TECHSTREAM (IG1 VOLTAGE VALUE)

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Turn the Techstream on.

(e) Start the engine.

(f) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

ABS/VSC/TRAC





(g) Measure the voltage output from the ECU displayed on the Techstream.

Result





B -- INSPECT SKID CONTROL ECU (IG1 TERMINAL)
A -- Continue to next step.

5. INSPECT SKID CONTROL ECU (EXI3 TERMINAL)

(a) for w/ Rear Differential Lock

(1) Disconnect the A4 skid control ECU connector.

(2) Measure the voltage according to the value(s) in the table below.





Standard Voltage:





Text in Illustration





(b) for w/o Rear Differential Lock

(1) Disconnect the A4 skid control ECU connector.

(2) Measure the voltage according to the value(s) in the table below.





Standard Voltage:





Text in Illustration





Result





B -- CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU EXI3 CIRCUIT)

C -- REPAIR OR REPLACE HARNESS OR CONNECTOR
A -- Continue to next step.

6. READ VALUE USING TECHSTREAM (ABS WARNING LIGHT)

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Turn the Techstream on.

(e) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

ABS/VSC/TRAC





(f) When performing the ABS Warning Light Active Test, check ABS Warning Light in the Data List Data List / Active Test.

ABS/VSC/TRAC





Result





B -- GO TO METER / GAUGE SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) How To Proceed With Troubleshooting

A -- REPLACE MASTER CYLINDER SOLENOID Disassembly

7. INSPECT SKID CONTROL ECU (IG1 TERMINAL)

(a) Disconnect the skid control ECU connector.

(b) Measure the voltage according to the value(s) in the table below.





Standard Voltage:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

8. INSPECT SKID CONTROL ECU (GND TERMINAL)

(a) Measure the resistance according to the value(s) in the table below.





Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE MASTER CYLINDER SOLENOID Disassembly

9. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU EXI3 CIRCUIT)

(a) Disconnect the A4 skid control ECU connector.

(b) Disconnect the L7 four wheel drive control ECU connector.

(c) Disconnect the D2 rear differential lock indicator switch connector.

(d) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

10. INSPECT REAR DIFFERENTIAL LOCK DETECTION SWITCH (DIFFERENTIAL LOCK INDICATOR SWITCH)

(a) Remove the rear differential lock detection switch Disassembly.

(b) Measure the resistance according to the value(s) in the table below.





Standard Resistance:





Text in Illustration





NG -- REPLACE DIFFERENTIAL LOCK INDICATOR SWITCH (REAR DIFFERENTIAL LOCK DETECTION SWITCH) Disassembly
OK -- Continue to next step.

11. INSPECT SKID CONTROL ECU (EXI3 TERMINAL)

(a) Disconnect the A4 skid control ECU connector.

(b) Connect the L7 four wheel drive control ECU connector.

(c) Measure the voltage according to the value(s) in the table below.





Standard Voltage:





Text in Illustration





NG -- REPLACE 4 WHEEL DRIVE CONTROL ECU NO.2

OK -- REPLACE MASTER CYLINDER SOLENOID Disassembly