Pinpoint Test F: DTCs C1277, C1278 and C1963
Anti-Lock Control
Pinpoint Tests
Pinpoint Test F: DTCs C1277, C1278 and C1963
Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number
Normal Operation
The steering wheel rotation (in degrees) is sent to the ABS module along circuits VSC06 (GY/BN) and VSC07 (VT/OG). Voltage is supplied to the steering wheel angle sensor from the ABS module along circuit CCS01 (VT/WH) and ground is provided by the ABS module through circuit RSC02 (BU/WH).
The steering wheel rotation sensor monitors the steering wheel position when the slotted wheel in the clockspring assembly rotates through the infrared light generated by the sensor.
- DTC C1277 Steering Wheel Angle 1 and 2 Circuit Failure - If during normal operation or the ABS module on-demand self test, the ABS module detects an open circuit, short to voltage or short to ground along circuits VCS06 (GY/BN) or VCS07 (VT/OG), DTC C1277 will be set. An internal failure of the steering wheel rotation sensor may also cause DTC C1277 to set.
- DTC 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.
- DTC C1963 Stability Assist Inhibit Warning - If conditions exist during normal operation that prevents the roll stability control system from operating, DTC C1963 will be set. This DTC is usually set due to the steering wheel rotation sensor or the stability control sensor cluster being damaged or installed incorrectly.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Steering wheel rotation sensor
PINPOINT TEST F: DTCs C1277, C1278 AND C1963
NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.
-------------------------------------------------
F1 MONITOR THE STEERING ROTATION SENSOR POSITION (SWA POS) PID
- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: DataLogger - ABS Module.
- Monitor the SWA POS PID while rotating the steering wheel clockwise and counterclockwise very slowly, from lock to lock.
- Does the PID move in intervals of 1.5 degrees?
Yes
CLEAR the DTCs. DRIVE the vehicle above 48 km/h (30 mph) with input from the steering wheel rotation sensor. RETRIEVE the DTCs. If DTC C1277 or C1278 is still present, GO to F10.
If DTC C1963 is present, INSPECT the steering wheel rotation sensor for damage and correct installation. REINSTALL or INSTALL new as necessary. If the sensor is OK, GO to F2.
No
GO to F2.
-------------------------------------------------
F2 CHECK THE VOLTAGE TO THE SENSOR
- Ignition OFF.
- Disconnect: Steering Wheel Rotation Sensor C226.
- Ignition ON.
- Measure the voltage between steering wheel rotation sensor C226-4, circuit CCS01 (VT/WH), harness side and ground.
- Is the voltage greater than 9.5 volts?
Yes
GO to F3.
No
REPAIR circuit CCS01 (VT/WH). CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
F3 CHECK THE VOLTAGE ON CIRCUIT RSC02 (BU/WH)
- Measure the voltage between steering wheel rotation sensor C226-4, circuit CCS01 (VT/WH), harness side and steering wheel rotation sensor C226-1, circuit RSC02 (BU/WH) harness side.
- Is the voltage greater than 9.5 volts?
Yes
GO to F4.
No
REPAIR circuit RSC02 (BU/WH). CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
F4 CHECK THE VOLTAGE ON CIRCUIT VSC06 (GY/BN)
- Measure the voltage between steering wheel rotation sensor C226-2, circuit VSC06 (GY/BN), harness side and steering wheel rotation sensor C226-1, circuit RSC02 (BU/WH) harness side.
- Is the voltage between 4.75 volts and 5.25 volts?
Yes
GO to F5.
No
REPAIR circuit VSC06 (GY/BN). CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
F5 CHECK THE VOLTAGE ON CIRCUIT VSC07 (VT/OG)
- Measure the voltage between steering wheel rotation sensor C226-3, circuit VSC07 (VT/OG), harness side and steering wheel rotation sensor C226-1, circuit RSC02 (BU/WH) harness side.
- Is the voltage between 4.75 volts and 5.25 volts?
Yes
GO to F6.
No
REPAIR circuit VSC07 (VT/OG). CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
F6 CHECK THE STEERING POSITION SENSOR HARNESS FOR AN OPEN
- Ignition OFF.
- Disconnect: ABS Module C155.
- Measure the resistance between the ABS module connector, harness side and the steering wheel rotation sensor connector, harness side as indicated in the following chart:
- Are the resistances less than 5 ohms?
Yes
GO to F7.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
F7 CHECK THE STEERING POSITION SENSOR CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and:
- ABS module C155-40, circuit RSC02 (BU/WH), harness side.
- ABS module C155-41, circuit VSC06 (GY/BN), harness side.
- ABS module C155-9, circuit VSC07 (VT/OG), harness side.
- ABS module C155-5, circuit CCS01 (VT/WH), harness side.
- Is any voltage present?
Yes
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
No
GO to F8.
-------------------------------------------------
F8 CHECK THE STEERING POSITION SENSOR CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between ground and:
- ABS module C155-40, circuit RSC02 (BU/WH), harness side.
- ABS module C155-41, circuit VSC06 (GY/BN), harness side.
- ABS module C155-9, circuit VSC07 (VT/OG), harness side.
- ABS module C155-5, circuit CCS01 (VT/WH), harness side.
- Are the resistances greater than 10,000 ohms?
Yes
GO to F9.
No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
F9 CHECK THE STEERING POSITION SENSOR CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between steering wheel rotation sensor C226-2, circuit VSC06 (GY/BN), harness side and steering wheel rotation sensor C226-3, circuit VSC07 (VT/OG) harness side.
- Are the resistances greater than 10,000 ohms?
Yes
INSTALL a new steering wheel rotation sensor. REFER to Steering Wheel Rotation Sensor Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
REPAIR the affected circuit(s). CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the scan tool directions for the calibration procedure. REPEAT the self-test.
-------------------------------------------------
F10 CHECK FOR CORRECT ABS MODULE OPERATION
- Ignition OFF.
- Disconnect: ABS Module C155.
- Check the connector for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: ABS Module C155.
- Make sure the connector seats correctly, then 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 Service and Repair. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------