C1257

BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: C1257: Power Supply Drive Circuit
C1257 - Power Supply Drive Circuit

DESCRIPTION

The motor relay (semiconductor relay) is built into the master cylinder solenoid and drives the pump motor based on a signal from the skid control ECU.





INSPECTION PROCEDURE

NOTICE:
When replacing the master cylinder solenoid, perform calibration Programming and Relearning.

PROCEDURE

1. CHECK PUMP MOTOR OPERATION

(a) Turn the ignition switch off.

(b) Disconnect the A6 skid control ECU connector.

(c) Depress the brake pedal more than 40 times.

(d) Turn the ignition switch to ON.

(e) Check pump motor operation.

OK:

Pump motor operates normally.

NG -- REPLACE MASTER CYLINDER SOLENOID Disassembly
OK -- Continue to next step.

2. RECONFIRM DTC

(a) Turn the ignition switch off.

(b) Reconnect the A6 skid control ECU connector.

(c) Turn the ignition switch to ON.

(d) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

(e) Turn the ignition switch off.

(f) Check if the same DTC is output Reading and Clearing Diagnostic Trouble Codes.

Result





B -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

A -- REPLACE MASTER CYLINDER SOLENOID Disassembly