ELECTRONICALLY CONTROLLED BRAKE SYSTEM ABS Warning Light Remains ON

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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.

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CAUTION / NOTICE / HINT

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PROCEDURE

1. Click here

   CHECK CAN COMMUNICATION SYSTEM

   
   

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

      Result
      Result Proceed to DTCs are not output. A DTCs are output. B

   
   
   • AClick here
   • B

     INSPECT CAN COMMUNICATION SYSTEM (Click here)

2. Click here

   CHECK IF BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY 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.

   
   
   • OKClick here
   • NG

     CONNECT CONNECTOR TO BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY CORRECTLY

3. Click here

   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

   
   
   • OKClick here
   • NG

     CHARGE OR REPLACE AUXILIARY BATTERY

4. Click here

   CHECK HARNESS AND CONNECTOR (IG1 TERMINAL)

   
   
   1. 

      Disconnect the A24 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 A24-16 (IG1) - Body ground Power switch on (IG) 11 to 14 V

      Table 1. Text in Illustration

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

   
   
   • OKClick here
   • NG

     REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

5. Click here

   CHECK HARNESS AND CONNECTOR (GND TERMINAL)

   
   
   1. 

      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 A24-28 (GND) - Body ground Always Below 1 Ω A24-27 (GND2) - Body ground Always Below 1 Ω A24-26 (GND3) - Body ground Always Below 1 Ω A24-25 (GND4) - Body ground Always Below 1 Ω A24-24 (GND5) - Body ground Always Below 1 Ω A24-23 (GND6) - Body ground Always Below 1 Ω

      Table 2. Text in Illustration

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

   
   
   • OKClick here
   • NG

     REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)

6. Click here

   INSPECT COMBINATION METER ASSEMBLY

   
   

   1. Reconnect the A24 skid control ECU (brake booster with master cylinder assembly) connector.

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

   3. Check the combination meter assembly.

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

      Result
      Result Proceed to OK (for LHD) A OK (for RHD) B NG C

      Tip:

      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).

   
   
   • A

     REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (Click here)

   • B

     REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (Click here)

   • C

     REPLACE COMBINATION METER ASSEMBLY (Click here)