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Home >> Ford >> 2000 >> Contour SE, 2.5 L, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 2339 (Anti-Lock Brake System - Vehicle Dynamic Systems) >> Diagnosis And Testing >> Anti-Lock Control - Non-Hybrid >> Pinpoint Tests >> Pinpoint Test F: DTCs C1277, C1278 and C1963 >> Normal Operation

Normal Operation

WARNING: This page is about a different car, the 2010 Mercury Milan, 2010 Lincoln MKZ, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

On vehicles equipped with Hydraulic Power Assist Steering (HPAS) (3.5L vehicles only), a slotted wheel is attached to the steering column inside the clockspring and the steering wheel rotation sensor is attached to the RH side of the multifunction switch just above the ignition lock cylinder. The steering wheel rotation senor has a LED and an opposing optical sensor. As the steering wheel is turned, the slotted wheel passes between the LED and the sensor, interrupting the signal and indicating how far and how fast the steering wheel is being turned. This information is sent to the ABS module and is used to help determine if the AdvanceTrac® system needs to be activated.

The steering wheel position information is sent to the ABS module along circuits VCA41 (VT/GN) and VCA42 (VT/OG). Voltage is supplied to the sensor by the ABS module along circuit CCA40 (GY/BU) and ground is provided by the ABS module along circuit RCA40 (BN/VT).

During normal operation, the voltage supplied to the sensor will not exceed 10V. If 12V is measured on the supply circuit at any time, the circuit is shorted to battery voltage.

On vehicles equipped with Electronic Power Assist Steering (EPAS), the steering wheel rotation sensor is located inside the EPAS gear assembly. Rotation speed and angle are sent to the ABS module from the Power Steering Control Module (PSCM) along the High Speed Controller Area Network (HS-CAN) bus.

DTC DESCRIPTION TABLE

DTC Description Fault Trigger Condition
  • C1277 - Steering Wheel Angle 1 and 2 Circuit Failure (vehicles with HPAS)
 If the ABS module detects an open circuit, short to voltage or short to ground along circuits VCA41 (VT/GN) and/or VCA42 (VT/OG) during normal operation or an on-demand self test, DTC C1277 will be set. An internal failure of the steering wheel rotation sensor may also cause DTC C1277 to set.
  • C1277 - Steering Wheel Angle 1 and 2 Circuit Failure (vehicles with EPAS)
 If the ABS module does not receive the steering wheel rotation/angle message from the PSCM for more than 5 seconds with vehicle speed above 3 km/h (2 mph), DTC C1277 will be set. This could be due to a failure of the HS-CAN bus or a failure of the EPAS system, which will cause other ABS module DTCs to set.
  • C1278 - Steering Wheel Angle 1 and 2 Signal Faulted
 If during normal operation or the ABS module on-demand self test, the ABS module does not receive the steering wheel rotation sensor input or if the input received does not agree with the input from other sensors, DTC C1278 will be set.
  • C1963 - Stability Assist Inhibit Warning
 If conditions exist during normal operation that prevent the AdvanceTrac® system from operating, DTC C1963 will be set. This DTC is usually set due to the steering wheel rotation sensor being damaged/installed incorrectly or due to invalid/missing data from the Restraints Control Module (RCM).

This pinpoint test is intended to diagnose the following: 

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