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HOMESERVICE MANUALSMERCURY2010MARINER PREMIER, 2.5 7, FWDREPAIR AND DIAGNOSIS (SINGLE PAGE)BRAKESTRACTION CONTROLANTI-LOCK BRAKE SYSTEM - VEHICLE DYNAMIC SYSTEMSDIAGNOSIS AND TESTINGANTI-LOCK CONTROL - NON-HYBRIDPINPOINT TESTSPINPOINT TEST I: DTCS C1277 AND C1278NORMAL OPERATION
2010 Mercury Mariner Premier, 2.5 7, FWD

Normal Operation

2010 Mercury Mariner Premier, 2.5 7, FWDSECTION 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 will expect to see the steering wheel angle message. If the message is missing for more than 100 milliseconds, DTC C1277 will be set. Low system voltage may cause an interruption in the HS-CAN  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 will be set.

    This pinpoint test is intended to diagnose the following: 

  • Wiring, terminals or connectors
  • Vehicle communications
  • PSCM 
  • ABS module
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.