Pinpoint Test G: DTC C1266 Anti-Lock Brake System (Abs) Power Valve Relay Circuit Failure

WARNING: This page is about a different car, the 2005 Mercury Sable and 2005 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.

G1 CHECK CIRCUIT 533 (TN/RD) FOR POWER
- Key in OFF position.
- Disconnect: ABS Module C135.
- Measure the voltage between the ABS module C135 pin 14, circuit 533 (TN/RD), harness side and ground.
  
  Fig 1: Measuring Voltage Between ABS Module C135 Pin 14, Circuit 533 (TN/RD), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to G2.
- No : REPAIR the circuit. CLEAR the DTCs. TURN the ignition switch from OFF to ON. REPEAT the ABS self-test. If any DTCs are retrieved, REFER to the ANTI-LOCK BRAKE SYSTEM (ABS) MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX . If no DTCs are retrieved, CARRY OUT a drive test above 15 km/h (9 mph), then REFER to the SYMPTOM CHART TEST the system for normal operation.
G2 CHECK CIRCUIT 1203 (BK/LB) FOR GROUND
- Key in OFF position.
- Measure the resistance between the ABS module C135 pin 15, circuit 1203 (BK/LB), harness side and ground.
  
  Fig 2: Measuring Resistance Between ABS Module C135 Pin 15, Circuit 1203 (BK/LB), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to G3.
- No : REPAIR the circuit. CLEAR the DTCs. TURN the ignition switch from OFF to ON. REPEAT the ABS self-test. If any DTCs are retrieved, REFER to the ANTI-LOCK BRAKE SYSTEM (ABS) MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX . If no DTCs are retrieved, CARRY OUT a drive test above 15 km/h (9 mph), then REFER to the SYMPTOM CHART . TEST the system for normal operation.
G3 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect all ABS connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all ABS connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- Yes : INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . TEST the system for normal operation.
- No : The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. TURN the ignition switch from OFF to ON. REPEAT the ABS self-test. If any DTCs are retrieved, REFER to the ANTI-LOCK BRAKE SYSTEM (ABS) MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX . If no DTCs are retrieved, CARRY OUT a drive test above 15 km/h (9 mph), then REFER to the SYMPTOM CHART .