Pinpoint Test H: DTC C1266 - ABS Valve Power Relay Circuit Failure

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Vehicle Dynamic Systems for schematic and connector information.

Normal Operation 

Fused battery voltage is provided to the ABS module from battery junction box (BJB) fuses 109 (20A) and 106 (40A) along circuits 483 (RD) and 601 (LB/PK) respectively. Fused ignition voltage is provided from central junction box (CJB) fuse 13 (10A) along circuit 1003 (GY/YE). When necessary, the ABS module supplies voltage to the hydraulic control unit (HCU) assembly and the pump motor is activated. The ABS module is provided a ground along circuit 57 (BK) and the hydraulic pump motor is provided a ground internally through the HCU.

• DTC C1266 ABS Valve Power Relay Circuit Failure - If the ABS module detects an open circuit or a short to ground in the valve power circuit, DTC C1266 will be set.

This pinpoint test is intended to diagnose the following:

• Fuse(s)
• Wiring, terminals or connectors
• ABS module

PINPOINT TEST H: DTC C1266 - ABS VALVE POWER RELAY CIRCUIT FAILURE 

1. H1 CHECK THE VOLTAGE TO THE ABS MODULE 
   • Disconnect: ABS module C135
   Fig 1: Checking ABS Module Circuit Voltage
   Courtesy of FORD MOTOR CO.
   • Measure the voltage between ABS module C135-14, circuit 483 (RD), harness side and ground.
   • Is the voltage greater than 10 volts? 
   1. YES  : INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) Module . TEST the system for normal operation.
   2. NO  : VERIFY BJB fuse 109 (20A) is OK. If OK, REPAIR circuit 483 (RD). CLEAR the DTCs. TEST the system for normal operation.