Pinpoint Test F: DTC C1277 and C1278

Anti-Lock Control

Pinpoint Tests

Pinpoint Test F: DTC C1277 and C1278

Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number

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 Smart Junction Box (SJB) fuse 34 (5A) along circuit CBP34 (VT/BN). Ground for the sensor is provided by the ABS module along circuit RCS02 (BU/WH). Steering wheel rotation (in degrees) is sent from the sensor to the ABS module along circuits VCS06 (GY/BN) and VCS07 (VT/OG).

- 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 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 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.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Steering wheel rotation sensor
- ABS module

PINPOINT TEST F: DTC C1277 AND C1278

NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

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.

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F1 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 F2.

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. 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.

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F2 CHECK THE ABS HARNESS AND MODULE FOR WATER INTRUSION

- Ignition OFF.
- Disconnect: ABS Module C135.
- 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 F3.

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F3 CALIBRATE THE ABS MODULE

- Connect: ABS Module C135.
- Connect the scan tool.
- Ignition ON.
- Using the scan tool, clear the ABS module DTCs.
- 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 C1278 is retrieved or the IVD Initialization sequence indicates a fault, GO to F4.

If any other DTCs are retrieved, GO to the ABS Module DTC Chart. Diagnostic Trouble Code Tests and Associated Procedures

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

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F4 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 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 C1278 is still present, GO to F12.

No
GO to F5.

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F5 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 C226-4, circuit CBP34 (VT/BN), harness side and ground.

- Is the voltage greater than 10 volts?

Yes
GO to F6.

No
VERIFY SJB fuse 34 (5A) is OK. If OK, REPAIR circuit CBP34 (VT/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. Diagrams By Number

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F6 CHECK THE STEERING WHEEL ROTATION SENSOR CIRCUITS FOR AN OPEN

- Ignition OFF.
- Disconnect: ABS Module C135.
- Measure the resistance between:
- ABS module C135-37, circuit VCS07 (VT/OG), harness side and steering wheel rotation sensor C226-3, circuit VCS07 (VT/OG), harness side.
- ABS module C135-12, circuit VCS06 (GY/BN), harness side and steering wheel rotation sensor C226-2, circuit VCS06 (GY/BN), harness side.
- ABS module C135-34, circuit RCS02 (BU/WH), harness side and steering wheel rotation sensor C226-1, circuit RCS02 (BU/WH), harness side.

- Are the resistances less than 5 ohms?

Yes
GO to F7.

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.

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F7 CHECK THE STEERING WHEEL ROTATION SENSOR CIRCUITS FOR A SHORT TO VOLTAGE

- Ignition ON.
- Measure the voltage between ground and:
- ABS module C135-37, circuit VCS07 (VT/OG), harness side.
- ABS module C135-12, circuit VCS06 (GY/BN), harness side.
- ABS module C135-34, circuit RCS02 (BU/WH), 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 F8.

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F8 CHECK THE STEERING WHEEL ROTATION SENSOR CIRCUITS FOR A SHORT TO GROUND

- Ignition OFF.
- Measure the resistance between ground and:
- ABS module C135-37, circuit VCS07 (VT/OG), harness side.
- ABS module C135-12, circuit VCS06 (GY/BN), harness side.
- ABS module C135-34, circuit RCS02 (BU/WH), harness side.

- Are the resistances greater than 10,000 ohms?

Yes
GO to F9.

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.

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F9 CHECK THE STEERING WHEEL ROTATION SENSOR SIGNAL 1 OUTPUT

NOTICE: This pinpoint test step directs testing circuits using a back-probe method. Use the special back-probe tool specified in the tool list. Do not force test leads or other probes into connectors. Adequate care must be exercised to avoid connector terminal damage while making sure that good electrical contact is made with the circuit or terminal. Failure to follow these instructions may cause damage to wiring, terminals or connectors and subsequent electrical faults.

- Connect: ABS Module C135.
- Connect: Steering Wheel Rotation Sensor C226.
- Ignition ON.
- With C226 connected, backprobe the connector to measure the voltage between steering wheel rotation sensor C226-2, circuit VCS06 (GY/BN), harness side and steering wheel rotation sensor C226-1, circuit RCS02 (BU/WH), 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 F10.

No
GO to F11.

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F10 CHECK THE STEERING WHEEL ROTATION SENSOR SIGNAL 2 OUTPUT

NOTICE: This pinpoint test step directs testing circuits using a back-probe method. Use the special back-probe tool specified in the tool list. Do not force test leads or other probes into connectors. Adequate care must be exercised to avoid connector terminal damage while making sure that good electrical contact is made with the circuit or terminal. Failure to follow these instructions may cause damage to wiring, terminals or connectors and subsequent electrical faults.

- With C226 connected, backprobe the connector to measure the voltage between the steering wheel rotation sensor C226-3, circuit VCS07 (VT/OG), harness side and the steering wheel rotation sensor C226-1, circuit RCS02 (BU/WH), harness side while rotating the steering wheel slightly.

- 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. CLEAR the DTCs. CARRY OUT the self-test with the brake pedal not applied.

No
GO to F12.

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F12 CHECK FOR CORRECT ABS MODULE OPERATION

- Disconnect: ABS Module C135.
- Check the connector for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: ABS Module C135.
- 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. 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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