DTC C1257: Power Supply Drive Circuit [08/2015 - ]: Procedure

1. Turn the ignition switch off.
2. Disconnect the A6 skid control ECU connector.
3. Depress the brake pedal more than 40 times.
4. Turn the ignition switch to ON.
5. Check pump motor operation.

   OK

   Pump motor operates normally.

Result: 

NG 

REPLACE MASTER CYLINDER SOLENOID 

(Refer to DISASSEMBLY [08/2015 - ] )

Result: 

OK 

See step  2

1. Turn the ignition switch off.
2. Reconnect the A6 skid control ECU connector.
3. Turn the ignition switch to ON.
4. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] , or refer to DTC CHECK / CLEAR [08/2019 - ] ).
5. Turn the ignition switch off.
6. Check if the same DTC is output (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] , or refer to DTC CHECK / CLEAR [08/2019 - ] ).
   RESULT
   
   

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

Result: 

A 

REPLACE MASTER CYLINDER SOLENOID 

(Refer to DISASSEMBLY [08/2015 - ] )

Result: 

B 

USE SIMULATION METHOD TO CHECK 

(Refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2015 - 08/2019] , or refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2019 - ] )