ELECTRONICALLY CONTROLLED BRAKE SYSTEM ABS Warning Light Remains ON

DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) is connected to the combination meter assembly via CAN communication.

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

• The skid control ECU (brake booster with master cylinder assembly) connector is disconnected from the brake booster with master cylinder assembly.

• There is a malfunction in the skid control ECU (brake booster with master cylinder assembly) internal circuit.

• There is an open in the harness between the combination meter assembly and the skid control ECU (brake booster with master cylinder assembly).

• The ABS control system is defective.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK CAN COMMUNICATION SYSTEM

   
   

   1. Check if CAN communication system DTCs are output Click here.

      Result
      Result Proceed to DTC is not output. A DTC is output. B

   
   

   B

   INSPECT CAN COMMUNICATION SYSTEM Click here

   A

2. CHECK IF SKID CONTROL ECU CONNECTOR IS SECURELY CONNECTED

   
   

   1. Check if the skid control ECU (brake booster with master cylinder assembly) connector is securely connected.

      OK
      The connector is securely connected.

   
   

   NG

   CONNECT CONNECTOR TO ECU CORRECTLY

   OK

3. CHECK AUXILIARY BATTERY

   
   

   1. Check the auxiliary battery voltage.

      Standard Voltage
      Tester Connection Condition Specified Condition Auxiliary battery Power switch on (IG) 11 to 14 V Auxiliary battery Power switch on (READY) 11 to 15.5 V

   
   

   NG

   CHARGE OR REPLACE AUXILIARY BATTERY

   OK

4. CHECK HARNESS AND CONNECTOR (IG1 TERMINAL)

   
   
   1. 

      Text in Illustration

      *a	Front view of wire harness connector (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

      Disconnect the skid control ECU (brake booster with master cylinder assembly) connector.

   2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition A28-16 (IG1) - Body ground Power switch on (IG) 11 to 14 V

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

   OK

5. CHECK HARNESS AND CONNECTOR (GND TERMINAL)

   
   
   1. 

      Text in Illustration

      *a	Front view of wire harness connector (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

      Turn the power switch off.

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

      Standard Resistance
      Tester Connection Condition Specified Condition A28-28 (GND) - Body ground Always Below 1 Ω A28-27 (GND2) - Body ground Always Below 1 Ω A28-26 (GND3) - Body ground Always Below 1 Ω A28-25 (GND4) - Body ground Always Below 1 Ω A28-24 (GND5) - Body ground Always Below 1 Ω A28-23 (GND6) - Body ground Always Below 1 Ω

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

   OK

6. INSPECT COMBINATION METER ASSEMBLY

   
   

   1. Reconnect the skid control ECU (brake booster with master cylinder assembly) connector.

   2. Perform the Active Test of the combination meter assembly (meter CPU) using the Techstream Click here.

   3. Check the combination meter assembly.

      OK
      The ABS warning light turns on or off in accordance with Techstream operation.

      Tech Tips

      If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step before replacing the part Click here.

   
   

   NG

   REPLACE COMBINATION METER ASSEMBLY Click here

   OK

   REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY Click here