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C1277




Anti-Lock Control - Traction Control and Stability Assist

Pinpoint Test M: DTCs B1104, C1277 and C1278


Normal Operation

The steering wheel rotation sensor monitors the steering wheel position when the toothed-wheel on the steering shaft passes through the optical field of the sensor.

The steering wheel rotation sensor receives fused ignition voltage from Battery Junction Box (BJB) fuse 53 (10A) along circuit CBB53 (GY/BN). Ground for the sensor is provided by the ABS module along circuit RCA09 (GN/VT). Steering wheel rotation (in degrees) is sent from the sensor to the ABS module along circuits VCS06 (GY/BN) and VCS07 (VT/OG).

- DTC B1104 (Steering Angle Sensor Signal Error)- If during normal operation or the on-demand self test the ABS module detects 2 back-to-back sensor edges within one millisecond or steering angle sensor voltage is in an invalid range for 1.2 seconds, DTC B1104 sets.

- DTC C1277 (Steering Wheel Angle 1 and 2 Circuit Failure)- If during normal operation or the on-demand self test the ABS module detects an open circuit, short to voltage or short to ground along circuit VCS06 (GY/BN) or VCS07 (VT/OG), DTC C1277 sets. An internal failure of the steering wheel rotation sensor may also cause DTC C1277 to set.

- DTC C1278 (Steering Wheel Angle 1 and 2 Circuit Faulted)- If during normal operation or the 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 sets.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Steering wheel rotation sensor

- ABS module

PINPOINT TEST M : DTCs B1104, C1277 AND C1278

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTICE: Overtightening of the steering wheel rotation sensor fasteners may deform or damage the sensor housing, possibly resulting in faulty operation.

NOTE: Make sure that the steering wheel rotation sensor is mounted securely to the column with 2 fasteners. A loose sensor or missing fastener may result in incorrect sensor operation. Examine the sensor/disk interface to make sure that the disk rotates freely within the slot of the sensor. Examine the disk for physical damage or blocked holes near the disk perimeter. Make sure that the sensor connector is mated securely to the harness connector. Before proceeding with electrical testing, make sure that the vehicle battery is fully charged.

M1 CHECK THE STEERING WHEEL ROTATION SENSOR INSTALLATION

- Verify that the steering wheel rotation sensor is mounted correctly and both fasteners are installed.

- Verify that the sensor disc is in good condition and free of obstructions and foreign materials.

Are the sensor and disc installed correctly and in good condition?

Yes
GO to M2.

No
CLEAN the disc and/or INSTALL a new sensor or fastener(s) as necessary. REFER to Steering Wheel Rotation Sensor Service and Repair.

CLEAR the DTCs. Using the scan tool, CARRY OUT the IVD Initialization sequence. DRIVE the vehicle above 48 km/h (30 mph) with input from the steering wheel rotation sensor. CARRY OUT the self-test with the brake pedal not applied.

M2 CHECK THE ABS HARNESS AND MODULE FOR WATER INTRUSION

- Ignition OFF.

- Disconnect: ABS Module C155.

- Inspect the ABS module connector and module for water intrusion.

Is there any evidence of water entry or corrosion?

Yes
CLEAN the connector and dry it out with low-pressure compressed air. INSPECT for evidence of water entry and repair as necessary. CLEAR the DTCs. CARRY OUT the self-test with the brake pedal not applied.

No
GO to M3.

M3 CALIBRATE THE ABS MODULE

- Connect: ABS Module C155.

- Connect the scan tool.

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: Self Test- Clear All CMDTCs (Continuous Memory Diagnostic Trouble Codes).

- Using the scan tool, carry out the IVD Initialization sequence.

- Test drive the vehicle above 48 km/h (30 mph) with input from the steering wheel rotation sensor.

- Enter the following diagnostic mode on the scan tool: Self Test- ABS Module.

Are any DTCs retrieved or does the calibration procedure indicate a fault?

Yes
If DTC B1104, C1277, C1278 or C1963 are retrieved or the IVD Initialization sequence indicates a fault, GO to M4.

If any other DTCs are retrieved, GO to the ABS Module DTC Chart. Anti-Lock Control

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

M4 MONITOR THE STEERING WHEEL ANGLE POSITION (SWA POS) PID

- 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.

Do the PIDs move in intervals of 4.5 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 B1104, C1277, C1278 or C1963 is still present, GO to M12.

No
GO to M5.

M5 CHECK FOR VOLTAGE TO THE STEERING WHEEL ROTATION SENSOR

- Ignition OFF.

- Disconnect: Steering Wheel Rotation Sensor C226.

- Ignition ON.

- Measure the voltage between steering wheel rotation sensor C226-1, circuit CBB53 (GY/BN), harness side and ground.





Is the voltage greater than 10 volts?

Yes
GO to M6.

No
VERIFY BJB (Battery Junction Box) fuse 53 (10A) is OK. If OK, REPAIR circuit CBB53 (GY/BN). If not OK, REFER to the Wiring Diagrams to locate the source of the circuit short. Using the scan tool, CARRY OUT the IVD Initialization sequence. CLEAR the DTCs. CARRY OUT the self-test with the brake pedal not applied. Electrical Diagrams

M6 CHECK THE STEERING WHEEL ROTATION SENSOR CIRCUITS FOR AN OPEN

- Ignition OFF.

- Disconnect: ABS Module C155.

- Measure the resistance between:
- ABS module C155-10, circuit VCS07 (VT/OG), harness side and steering wheel rotation sensor C226-2, circuit VCS07 (VT/OG), harness side.

- ABS module C155-39, circuit VCS06 (GY/BN), harness side and steering wheel rotation sensor C226-3, circuit VCS06 (GY/BN), harness side.

- ABS module C155-24, circuit RCA09 (GN/VT), harness side and steering wheel rotation sensor C226-4, circuit RCA09 (GN/VT), harness side.






Are the resistances less than 5 ohms?

Yes
GO to M7.

No
REPAIR the affected circuit(s). Using the scan tool, CARRY OUT the IVD Initialization sequence. CLEAR the DTCs. CARRY OUT the self-test with the brake pedal not applied.

M7 CHECK THE STEERING WHEEL ROTATION SENSOR CIRCUITS FOR A SHORT TO VOLTAGE

- Ignition ON.

- Measure the voltage between ground and:
- ABS module C155-10, circuit VCS07 (VT/OG), harness side.

- ABS module C155-39, circuit VCS06 (GY/BN), harness side.

- ABS module C155-24, circuit RCA09 (GN/VT), harness side.






Is any voltage present?

Yes
REPAIR the affected circuit(s). Using the scan tool, CARRY OUT the IVD Initialization sequence. CLEAR the DTCs. CARRY OUT the self-test with the brake pedal not applied.

No
GO to M8.

M8 CHECK THE STEERING WHEEL ROTATION SENSOR CIRCUITS FOR A SHORT TO GROUND

- Ignition OFF.

- Measure the resistance between ground and:
- ABS module C155-10, circuit VCS07 (VT/OG), harness side.

- ABS module C155-39, circuit VCS06 (GY/BN), harness side.

- ABS module C155-24, circuit RCA09 (GN/VT), harness side.






Are the resistances greater than 10,000 ohms?

Yes
GO to M9.

No
REPAIR the affected circuit(s). Using the scan tool, CARRY OUT the IVD Initialization sequence. CLEAR the DTCs. CARRY OUT the self-test with the brake pedal not applied.

M9 CHECK THE STEERING WHEEL ROTATION SENSOR SIGNAL 1 OUTPUT

- Connect: ABS Module C155.

- Connect: Steering Wheel Rotation Sensor C226.

- Ignition ON.

- With C226 connected, backprobe the connector to measure the voltage between steering wheel rotation sensor C226-3, circuit VCS06 (GY/BN), harness side and steering wheel rotation sensor C226-4, circuit RCA09 (GN/VT), harness side while rotating the steering wheel slightly.





Is the voltage between 0.25 volt and 0.75 volt or between 4.00 volts and 4.75 volts with the steering wheel stationary and change to the other state when rotating the steering wheel slightly?

Yes
GO to M10.

No
GO to M11.

M10 CHECK THE STEERING WHEEL ROTATION SENSOR SIGNAL 2 OUTPUT

- With C226 connected, backprobe the connector to measure the voltage between the steering wheel rotation sensor C226-2, circuit VCS07 (VT/OG), harness side and the steering wheel rotation sensor C226-4, circuit RCA09 (GN/VT), harness side while rotating the steering wheel slightly.





Is the voltage between 0.25 volt and 0.75 volt or between 4.00 volts and 4.75 volts with the steering wheel stationary and change to the other state when rotating the steering wheel slightly?

Yes
GO to M12.

No
GO to M11.

M11 CHECK FOR STEERING WHEEL ROTATION SENSOR REFERENCE VOLTAGE

- Ignition OFF.

- Disconnect: Steering Wheel Rotation Sensor C226.

- Ignition ON.

- Measure the voltage between steering wheel rotation sensor C2226-4, circuit RCA09 (GN/VT), harness side and:
- steering wheel rotation sensor C226-3, circuit VCS06 (GY/BN), harness side.

- steering wheel rotation sensor C226-2, circuit VCS07 (VT/OG), harness side.






Are the voltages between 4.75 volts and 5.25 volts?

Yes
INSTALL a new steering wheel rotation sensor. REFER to Steering Wheel Rotation Sensor Service and Repair. Using the scan tool, CARRY OUT the IVD Initialization sequence. CLEAR the DTCs. CARRY OUT the self-test with the brake pedal not applied.

No
GO to M12.

M12 CHECK FOR CORRECT ABS MODULE OPERATION

- Disconnect: ABS Module C155.

- Check the connector for:
- corrosion.
- pushed-out pins.
- spread terminals.


- Connect: ABS Module C155.

- Make sure the connector is fully seated and locked, 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. CLEAR the DTCs. Using the scan tool, CARRY OUT the IVD Initialization sequence. CARRY OUT the self-test with the brake pedal not applied.

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.

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