PINPOINT TEST I: DTCs C1277 AND C1278

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

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 all Continuous Memory Diagnostic Trouble Codes (CMDTCs).
- Are there any communication (U-code) DTCs present in the ABS module or any other modules?
1. 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 .
  
  For all other modules, REFER to the Master DTC Chart in MULTIFUNCTION ELECTRONIC MODULES .
2. No: GO to I2 .
I2 CHECK THE PSCM COMMUNICATIONS
- Review the results from the Network Test.
- Did the PSCM pass the Network Test?
1. Yes: GO to I3 .
2. No: REFER to the Symptom Chart in MODULE COMMUNICATIONS NETWORK to diagnose the no communication issue.
I3 CHECK THE PSCM FOR NON-COMMUNICATION DTCs
- Review the DTCs recorded after the Network Test.
- Are DTCs B1342, B2277, B2278 and/or B227B present in the PSCM ?
1. Yes: REFER to STEERING SYSTEM to diagnose the PSCM DTCs.
2. 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?
1. Yes: GO to I7.
2. 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 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?
1. Yes: GO to I6 .
2. No: REPAIR or INSTALL new as necessary.
  Refer to appropriate SYSTEM WIRING DIAGRAMS article for schematic and connector information.
  
  CLEAR the DTCs. REPEAT the self-test.
I6 CHECK FOR AN INTERMITTENT CONCERN
- Connect: PSCM 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?
1. Yes: REPAIR or INSTALL new as necessary.
  Refer to appropriate SYSTEM WIRING DIAGRAMS article for schematic and connector information.
  
  CLEAR the DTCs. REPEAT the self-test.
2. 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?
1. Yes: INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . CLEAR the DTCs. REPEAT the self-test.
2. No: INSTALL a new steering column. REFER to STEERING COLUMN . CLEAR the DTCs. REPEAT the self-test.