Short to B+ in ABS Motor Relay Circuit - Vehicle Stability Control System

BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM: C0273/13,C0274/14,C1361/91: Open in ABS Motor Relay Circuit
C1361/91 - Short Circuit in ABS Motor Fail Safe Relay Circuit

DESCRIPTION

If a DTC of the motor line is stored, the ABS motor fail safe relay cuts off the power supply to the ABS motor relay and performs fail safe.

While any of the ABS, TR(A)C, VSC, or BA is operating, the skid control ECU turns the ABS motor relay on and activates the pump motor in the brake actuator.

This code may be stored if the motor relay (+BM) voltage is lower than the DTC detecting condition due to insufficient output from the battery or alternator.





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
When replacing the skid control ECU, perform zero point calibration and store system information Vehicle Stability Control System.

PROCEDURE

1. INSPECT ABS1 FUSE

(a) Remove the ABS1 fuse from engine room No. 1 relay block.





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

Standard resistance:





NG -- REPLACE ABS1 FUSE
OK -- Continue to next step.

2. INSPECT ABS MOTOR RELAY (ABS MOTOR2)

(a) Install the ABS1 fuse.





(b) Remove the ABS MOTOR2 relay.

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

Standard resistance:





NG -- REPLACE ABS MOTOR RELAY (ABS MOTOR2)
OK -- Continue to next step.

3. INSPECT ABS MOTOR RELAY (ABS MOTOR1 (FAIL SAFE))

(a) Remove the ABS MOTOR1 (fail safe) relay.





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

Standard resistance:





NG -- REPLACE ABS MOTOR RELAY (ABS MOTOR1 (FAIL SAFE))
OK -- Continue to next step.

4. INSPECT ENGINE ROOM NO. 3 RELAY BLOCK (POWER SOURCE TERMINAL)

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





Standard voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)
OK -- Continue to next step.

5. INSPECT ENGINE ROOM NO. 3 RELAY BLOCK

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





Standard resistance:





NG -- REPAIR OR REPLACE ENGINE ROOM NO. 3 RELAY BLOCK
OK -- Continue to next step.

6. INSPECT BRAKE ACTUATOR ASSEMBLY

(a) Make sure that there is no looseness at the locking part and the connecting part of the connector.





(b) Disconnect the brake actuator connector.

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

Standard resistance:





NG -- REPLACE BRAKE ACTUATOR ASSEMBLY Removal
OK -- Continue to next step.

7. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR - ENGINE ROOM NO. 3 RELAY BLOCK)

(a) 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.

8. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BRAKE ACTUATOR)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connector.





(b) Disconnect the skid control ECU connector.

(c) 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.

9. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - ENGINE ROOM NO. 3 RELAY BLOCK)

(a) Make sure that there is no looseness at the locking part and the connecting part of the connector.





(b) Disconnect the skid control ECU connector.

(c) 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. RECONFIRM DTC

(a) Clear the DTCs Vehicle Stability Control System.

(b) Start the engine.

(c) Drive the vehicle at a speed of 20 km/h (12 mph) or more for 30 seconds or more.

(d) Check if the same DTC is recorded Vehicle Stability Control System.

HINT
Reinstall the relays, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

Result:





HINT
* If a speed signal of 6 km/h (4 mph) or more is input to the skid control ECU with the engine switch on (IG) and the stop light switch off, the ECU performs self diagnosis of the motor and solenoid circuits.
* If the normal system code is output (no trouble codes are output), slightly jiggle the connectors, wire harness, and fuses of the skid control ECU and/or brake actuator assembly. Make sure that no DTCs are output.
* If any DTCs are output while jiggling a connector or wire harness of the skid control ECU and/or brake actuator assembly, inspect and repair the connector or wire harness.
* It is suspected that the DTCs were output due to a bad connection of the connector terminal.
B -- REPLACE SKID CONTROL ECU Removal

A -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Diagnosis System