C1278
Anti-Lock Control - Non-Hybrid
Pinpoint Test I: DTCs C1277 and C1278
Normal Operation
The ABS module receives steering wheel angle information as a message from the Power Steering Control Module (PSCM) over the High Speed Controller Area Network (HS-CAN). The ABS module uses the steering wheel angle information to aid in determining when and if intervention is needed for a stability event.
- DTC C1277 (Steering Wheel Angle 1 and 2 Circuit Failure)- After the ignition is turned to the ON (RUN) position, after the ABS module has initialized (approximately 2 seconds) and with vehicle speed greater than 3 km/h (1.8 mph), the ABS module expects to see the steering wheel angle message. If the message is missing for more than 100 milliseconds, DTC C1277 sets. Low system voltage may cause an interruption in the HS-CAN (High Speed Controller Area Network) message which could cause DTC B1277 to set.
- DTC C1278 (Steering Wheel Angle 1 and 2 Signal Faulted)- After the ignition is turned to the ON (RUN) position, after the ABS module has initialized (approximately 2 seconds) and with vehicle speed greater than 3 km/h (1.8 mph), if the steering wheel angle message is outside the expected range but is not missing or invalid, DTC C1278 sets.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Vehicle communications
- PSCM (Power Steering Control Module)
- ABS module
PINPOINT TEST I : DTCs C1277 AND C1278
I1 CHECK OTHER MODULES FOR COMMUNICATION ISSUES
- Connect the scan tool.
- Ignition ON.
- Using the scan tool, carry out a Network Test.
- Retrieve and record allContinuous Memory Diagnostic Trouble Codes (CMDTCs).
Are there any communication (U-code) DTCs present in the ABS module or any other modules?
Yes
DIAGNOSE all U-code DTCs before diagnosing DTC C1277 or C1278. For ABS module U-code DTCs, REFER to the ABS Module DTC Chart Anti-Lock Control. For all other modules, REFER to the Master DTC Chart in Body Control Systems Body Control Systems.
No
GO to I2.
I2 CHECK THE PSCM (Power Steering Control Module) COMMUNICATIONS
- Review the results from the Network Test.
Did the PSCM (Power Steering Control Module) pass the Network Test?
Yes
GO to I3.
No
REFER to the Symptom Chart in Information Bus to diagnose the no communication issue Symptom Related Diagnostic Procedures.
I3 CHECK THE PSCM (Power Steering Control Module) FOR NON-COMMUNICATION DTCs
- Review the DTCs recorded after the Network Test.
Are DTCs B1342, B2277, B2278 and/or B227B present in the PSCM (Power Steering Control Module) ?
Yes
REFER to Steering to diagnose the PSCM (Power Steering Control Module) DTCs.
No
GO to I4.
I4 CHECK FOR RETURNING ABS MODULE DTCs
- Using the scan tool, clear the ABS module DTCs.
- Ignition OFF.
- Ignition ON.
- Test drive the vehicle and make several turns or circles in both directions.
- Enter the following diagnostic mode on the scan tool: Self Test- ABS Module.
Are DTCs C1277 and/or C1278 present in the ABS module?
Yes
GO to I7.
No
The condition to set the DTC is not present at this time. The DTC may have been set by an intermittent condition. GO to I5.
I5 CHECK THE HARNESS AND CONNECTORS
- Ignition OFF.
- Disconnect: PSCM (Power Steering Control Module) C2231A.
- Disconnect: ABS Module C155.
- Inspect both connectors for:
- corrosion.
- spread terminals.
- bent pins.
- pushed-out pins and terminals.
- Inspect the wire harnesses associated with the connectors for:
- corrosion.
- pinched, cut or pierced wires.
Are the connectors and harnesses OK?
Yes
GO to I6.
No
REPAIR or INSTALL new as necessary. Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information Electrical Diagrams. CLEAR the DTCs. REPEAT the self-test.
I6 CHECK FOR AN INTERMITTENT CONCERN
- Connect: PSCM (Power Steering Control Module) C2231A.
- Connect: ABS Module C155.
- Ignition ON.
- Attempt to recreate the fault by wiggling connectors (including any in-line connectors) and flexing the wire harness, tilting and rotating the steering wheel frequently.
- Enter the following diagnostic mode on the scan tool: Self Test- ABS Module.
Are DTCs C1277 and/or C1278 present in the ABS module?
Yes
REPAIR or INSTALL new as necessary. Refer to Wiring Diagram Set 5, Connector Repair Procedures for schematic and connector information Electrical Diagrams. CLEAR the DTCs. REPEAT the self-test.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
I7 CHECK 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 from lock to lock.
Does the PID change when the steering wheel is turned?
Yes
INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) Module . CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new steering column. CLEAR the DTCs. REPEAT the self-test.