PINPOINT TEST M: DTCs C0021:21, 66 AND 77

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.

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

M1 CHECK THE DTCs FROM THE SELF-TEST
- Review the DTCs retrieved and recorded in Inspection and Verification.
- Are other DTCs present along with DTC C0021:21, 66 or 77?
1. Yes: GO to M2 .
2. No: The other ABS module DTCs will indicate the cause of DTCs C0021:21, 66 and/or 77.
  CORRECT all other ABS module DTCs. REFER to the ABS MODULE DTC CHART .
M2 CHECK THE BRAKE PEDAL AND BRACKET
- Inspect the brake pedal and bracket and the clevis end of the booster push rod for misalignment or damage. Verify that all brake pedal and bracket fasteners are tightened to the specified torque. Apply and release the brake pedal. Verify that the brake pedal moves freely and returns to the full released position.
- Is the brake pedal and bracket OK?
1. Yes: GO to M3 .
2. No: REPAIR or INSTALL new components as necessary. REFER to HYDRAULIC BRAKE ACTUATION .
M3 CHECK THE BRAKE BOOSTER AND BRAKE MASTER CYLINDER
- Inspect the brake booster and brake master cylinder for misalignment or damage. Verify that all brake booster and master cylinder fasteners are tightened to the specified torque.
- Is the brake booster and the brake master cylinder OK?
1. Yes: GO to M4 .
2. No: REPAIR or INSTALL new components as necessary. REFER to POWER BRAKE ACTUATION for the brake booster. REFER to HYDRAULIC BRAKE ACTUATION for the brake master cylinder.
M4 CHECK FOR VACUUM LEAKS
- Inspect the vacuum pump and brake booster vacuum hoses, lines and fittings for vacuum leaks.
- Are the vacuum pump and brake booster vacuum hoses, lines and fittings OK?
1. Yes: GO to M5 .
2. No: REPAIR or INSTALL new components as necessary. REFER to POWER BRAKE ACTUATION .
M5 CHECK THE BRAKE SYSTEM FOR BRAKE FLUID LEAKS
- Inspect the brake system for brake fluid leaks.
- Are any brake fluid leaks found?
1. Yes: REPAIR as necessary. FILL the brake master cylinder reservoir using the specified brake fluid. CARRY OUT the brake system service bleed. REFER to Brake System Bleeding - Hybrid in BRAKE SYSTEM - GENERAL INFORMATION .
2. No: GO to M6 .
M6 CHECK FOR AIR IN THE BRAKE SYSTEM
- Carry out the brake system service bleed. Refer to Brake System Bleeding in BRAKE SYSTEM - GENERAL INFORMATION .
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self Test - Clear all CMDTCs .
- Disconnect the scan tool.
- Test drive the vehicle at speeds greater than 32 km/h (20 mph).
- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self Test - ABS Module.
- Carry out the ABS module self-test.
- Are DTCs C0021:21, 66 and 77 present?
1. Yes: GO to M7 .
2. No: The system is operating correctly at this time. The concern may have been caused by air trapped in the hydraulic brake system. CLEAR the DTCs. REPEAT the self-test.
M7 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect: ABS Module C155.
- Check for:
  - corrosion.
  - pushed-out pins.
  - spread terminals.
- Connect: ABS Module C155.
- Make sure the connector is seated correctly, then operate the system and verify the concern is still present.
- Is the concern still present?
1. Yes: INSTALL a ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . TEST the system for normal operation. CLEAR the DTCs. DRIVE the vehicle.
  REPEAT the self-test. If the DTCs identified in the normal operation of this pinpoint test are retrieved, INSTALL a new HCU . REFER to HYDRAULIC CONTROL UNIT (HCU) - HYBRID .
2. 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.