ABS Warning Light Circuit: Wiring Diagram

Fig 1: ABS Warning Light Wiring Diagram

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

• When using the intelligent tester, start form *1 if the ABS warning light does not light up, or start form *3 if the ABS warning light remains on.
• When not using the intelligent tester, start form *2 if the ABS warning light does not light up, or start form *4 if the ABS warning light remains on.

1. PERFORM ACTIVE TEST BY INTELLIGENT TESTER (ABS WARNING LIGHT)*1 
   1. Select the ACTIVE TEST, generate a control command, and then check that the ABS warning light operates.

   Skid control ECU 

   ACTIVE TEST REFERENCE CHART
   
   

   Item	Vehicle Condition / Test Details	Diagnostic Note
   ABS WARN LIGHT	Turn ABS warning light ON / OFF	Observe combination meter

   OK : ABS warning light turns on or off. 

   OK : REPLACE SKID CONTROL ECU ASSEMBLY 

   NG : Go To Next Step 

2. CHECK ABS WARNING LIGHT*2 
   1. Disconnect the A40 ECU connector.
   2. Turn the ignition switch ON.
   3. Using a service wire, connect terminal WA to GND3 or GND4 of the A40 ECU connector. Check the ABS warning light.

      OK : ABS warning light turns off. 

   4. Turn the ignition switch OFF.
   5. Remove the service wire.
   6. Turn the ignition switch ON. Check the ABS warning light.

   OK : ABS warning light illuminates. 

   OK : REPLACE SKID CONTROL ECU ASSEMBLY 

   NG : Go To Next Step 

3. INSPECT RELAY (Marking: IG1 NO. 2) 
   1. Remove the IG1 NO. 2 relay from the cowl side junction block LH.
   2. Measure the resistance of the relay.

   Standard resistance 

   TESTER CONNECTION AND SPECIFIED CONDITION CHART
   
   

   Tester Connection	Specified Condition
   1 - 2	10 kΩ or higher
   1 - 2	Below 1 Ω (when battery voltage is applied to terminals 3 and 4)

   NG : REPLACE RELAY 

   Fig 2: Identifying Relay Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK : CHECK COMBINATION METER (COMBINATION METER CIRCUIT) 

4. INSPECT SKID CONTROL ECU CONNECTOR*3 
   1. Check that each ECU connector is properly installed.

   OK : Each ECU connector is properly installed. 

   NG : CONNECT CONNECTOR TO ECU CORRECTLY 

   OK : Go To Next Step 

5. PERFORM ACTIVE TEST BY INTELLIGENT TESTER (ABS WARNING LIGHT) 
   1. Select the ACTIVE TEST, generate a control command, and then check that the ABS warning light operates.

   Skid control ECU 

   ACTIVE TEST REFERENCE CHART
   
   

   Item	Vehicle Condition / Test Details	Diagnostic Note
   ABS WARN LIGHT	Turn ABS warning light ON / OFF	Observe combination meter

   OK : ABS warning light turns on or off. 

   OK : REPLACE SKID CONTROL ECU ASSEMBLY 

   NG : Go To Next Step 

6. CHECK FOR DTC*4 
   1. Turn the ignition switch ON.
   2. Check that the ABS warning light illuminates.
   3. Check if the same DTCs are recorded.

   Result: 

   RESULT REFERENCE
   
   

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

   B : REPAIR CIRCUIT INDICATED BY OUTPUT DTC 

   A : Go To Next Step 

7. CHECK WIRE HARNESS (SKID CONTROL ECU ASSEMBLY - COMBINATION METER) 

   NG : REPAIR OR REPLACE HARNESS AND CONNECTOR 

   OK : REPLACE SKID CONTROL ECU ASSEMBLY