Anti-Lock Brake

BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: ANTI-LOCK BRAKE SYSTEM: C0273/13,C0274/14: Open in ABS Motor Relay Circuit
C0274/14 - Short to B+ in ABS Motor Relay Circuit

DESCRIPTION

The ABS motor relay supplies power to the ABS pump motor. While the ABS is activated, the ECU turns the motor relay on and operates the ABS pump motor.

If the voltage supplied to the motor relay (+BM) is below the DTCs detection threshold due to low voltage from the battery or alternator, these DTCs may be stored.





WIRING DIAGRAM





INSPECTION PROCEDURE

HINT
When C1241/41 is output together with C0273/13 and/or C0274/13, inspect and repair the trouble areas indicated by C1241/41 first Low Battery Positive Voltage or Abnormally High Battery Positive Voltage - ABS (Antilock Brake System).

PROCEDURE

1. INSPECT ABS NO. 1 FUSE

(a) Remove the ABS NO. 1 fuse from the engine room relay block.





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

Standard Resistance:





NG -- REPLACE ABS NO. 1 FUSE
OK -- Continue to next step.

2. PERFORM ACTIVE TEST USING TECHSTREAM (ABS MOTOR RELAY)

(a) Install the ABS NO. 1 fuse.

(b) Connect the Techstream to the DLC3.

(c) Start the engine.

(d) Select Active Test mode on the Techstream Data List / Active Test.

ABS/VSC/TRAC

ABS/VSC/TRAC:

(e) Check the operating sound of the ABS motor relay when operating it with the Techstream.

Result:





B -- RECONFIRM DTC
A -- Continue to next step.

3. INSPECT SKID CONTROL ECU (+BM TERMINAL)

(a) Turn the ignition switch off.





(b) Disconnect the skid control ECU connector.

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

Standard Voltage:





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

4. INSPECT SKID CONTROL ECU (GND2 TERMINAL)

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





Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (GND2 CIRCUIT)
OK -- Continue to next step.

5. RECONFIRM DTC

HINT
This code is detected when a problem is identified in the brake actuator assembly.

The ABS motor relay is in the brake actuator assembly.

Therefore, ABS motor relay inspection and motor relay unit inspection cannot be performed. Be sure to check if the DTC is output before replacing the brake actuator assembly.

(a) Turn the ignition switch off.

(b) Reconnect the skid control ECU connector.

(c) Clear the DTCs ABS (Antilock Brake System).

(d) Start the engine.

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

(f) Check if the same DTC is recorded ABS (Antilock Brake System).

Result:





HINT
* If a speed signal of 6 km/h (4 mph) or more is input to the skid control ECU with the ignition switch ON 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 brake actuator assembly. Make sure that no DTCs are output.
* If any DTCs are output while jiggling a connector or wire harness of the brake actuator assembly (skid control ECU), 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 BRAKE ACTUATOR ASSEMBLY Removal

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