Ford Mustang (1999-2004) Service Manual: Pinpoint Tests

PINPOINT TEST A: THE BRAKES PULL OR DRIFT

Test Step Result / Action to Take
A1 CHECK THE TIRES Yes

GO to A2 .

No

CORRECT as necessary.

RETEST for normal operation.

NOTE: Check tire pressure with the brakes off.
  • Check tires for uneven and excessive wear and for correct pressure.

  • Are the tires OK?
A2 CHECK THE ALIGNMENT Yes

GO to A3 .

No

CORRECT alignment as necessary. RETEST for correct operation.

  • Check the caster, camber and toe.

  • Is the alignment OK?
A3 CHECK THE DISC BRAKE COMPONENTS Yes

GO to A4 .

No

REPAIR or INSTALL new components as necessary.

RETEST for normal operation.

  • Check all disc brake calipers, anchor plate guide pins and brake pads for binding, wear, damage, contamination and correct installation.

  • Are the disc brake calipers, anchor plate guide pins and brake pads OK?
A4 ROAD TEST THE VEHICLE Yes

REPAIR or INSTALL new front disc brake caliper or anchor plate guide pins on the side opposite to the direction of the drift or pull.

No

REPAIR or INSTALL new front disc brake caliper or anchor plate guide pins on the side of the vehicle in the direction of the drift or pull.

  • Road test the vehicle, and observe whether the drift occurs with or without the brakes applied.
  • Does the drift or pull occur with the brakes applied?

PINPOINT TEST B: THE RED BRAKE WARNING INDICATOR IS ALWAYS ON

Test Step Result / Action to Take
B1 CHECK THE BRAKE MASTER CYLINDER FLUID LEVEL SWITCH Yes

GO to B2 .

No

INSTALL a new brake master cylinder reservoir. TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Brake Master Cylinder Fluid Level Switch C124.
  • Connect a fused jumper from C124-2 circuit 977 (PK/WH) to C124-3 circuit 128 (VT/YE).

  • Key in ON position.
  • Does the brake warning indicator stay on?
B2 CHECK PARKING BRAKE SWITCH Yes

GO to B3 .

No

INSTALL a new parking brake switch. TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Parking Brake Switch.
  • Key in ON position.
  • Does the brake warning light stay on?
B3 CHECK THE GEM Yes

REPAIR the GEM. TEST the system for normal operation.

No

For vehicles without Daytime Running Lights (DRL), GO to B4 . For vehicles with DRL, GO to B5 .

  • Key in OFF position.
  • Disconnect: GEM C201e.
  • Measure resistance to ground at C201e-13.

  • Is the resistance greater than 10,000 ohms?
B4 CHECK CIRCUITS 977 (VT/WH), 22 (LB/BK) AND 128 (VT/YE) Yes

REPAIR the ground short in circuit 128 (VT/YE). TEST the system for normal operation.

No

REPAIR the ground short in circuit 977 (VT/WH) or circuit 22 (LB/BK). TEST the system for normal operation.

  • Remove the fused jumper from C124.
  • Measure the resistance to ground at C124-2.

  • Is the resistance greater than 10,000 ohms?
B5 CHECK CIRCUIT 128 (VT/YE) Yes

GO to B6 .

No

REPAIR the ground short in circuit 128 (VT/YE). TEST the system for normal operation.

  • Remove the fused jumper from C124.
  • Measure the resistance to ground at C201e-13.

  • Is the resistance greater than 10,000 ohms?
B6 CHECK DAYTIME RUNNING LIGHTS (DRL) MODULE Yes

REPAIR the DRL module. TEST the system for normal operation.

No

REPAIR the ground short in circuit 22 (LB/BK) or 977 (VT/WH). TEST the system for normal operation.

  • Disconnect: DRL Module C1030.
  • Measure the resistance to ground at C124-2.

  • Is the resistance greater than 10,000 ohms?

PINPOINT TEST C: BRAKE LOCKUP DURING LIGHT BRAKE PEDAL FORCE

Test Step Result / Action to Take
C1 INSPECT THE TIRES Yes

GO to C2 .

No

CORRECT as necessary. RETEST for normal operation.

  • Inspect the tires for uneven or excessive wear, correct pressure, correct size and type.
  • Are the tires OK?
C2 CHECK THE BRAKE CALIPER COMPONENTS Yes

GO to C3 .

No

CORRECT as necessary. RETEST for normal operation.

  • Inspect the brake pads and brake discs for wear, damage, contamination and correct installation.
  • Are the brake components OK?
C3 CHECK THE PROPORTIONING VALVE Yes

INSPECT the disc brake calipers and INSTALL new calipers as necessary.

RETEST for normal operation.

No

INSTALL a new proportioning valve.

RETEST for normal operation.

  • Install the gauges from the ABS brake and pressure test kit on one front and one rear bleeder screw.
  • Apply 6895 kPa (1000 psi) to the front brake system.
  • Is the pressure in the rear system 3516-4481 kPa (510-650 psi)?

PINPOINT TEST D: EXCESSIVE/ERRATIC BRAKE PEDAL TRAVEL

Test Step Result / Action to Take
D1 CHECK FOR SPONGY PEDAL Yes

BLEED the brake system. REFER to Bleeding - System in this section.

RETEST for normal operation.

No

GO to D2 .

  • Key in ON position.
  • Operate the brake pedal and note pedal feel.
  • Does the pedal feel spongy?
D2 CHECK THE BRAKE PEDAL Yes

GO to D3 .

No

REPAIR or INSTALL a new brake pedal as necessary. RETEST for normal operation.

  • Inspect the brake pedal and bracket for binding, obstruction or damage.
  • Is the brake pedal OK?
D3 CHECK THE BRAKE COMPONENTS Yes

GO to D4 .

No

REPAIR or INSTALL new components as necessary. RETEST for normal operation.

  • Inspect the calipers bolts, anchor plate bolts and anti-rattle springs for binding, damage, contamination and correct installation.
  • Are the bolts and springs OK?
D4 CHECK THE BOOSTER AND MASTER CYLINDER Yes

INSPECT the front wheel bearings for wear, damage and correct installation and the rear axle end play. CORRECT as necessary. RETEST for normal operation.

No

CORRECT as necessary. RETEST for normal operation.

  • Check the power brake booster and brake master cylinder for correct installation and correct push rod adjustment.
  • Are the power brake booster and the brake master cylinder OK?

PINPOINT TEST E: HYDRO-BOOST, NO POWER ASSIST

Test Step Result / Action to Take
E1 CHECK FLUID LEVEL IN POWER STEERING PUMP Yes

GO to E2 .

No

CHECK for leakage of power steering fluid. ADD fluid as necessary.

  • Check fluid level in power steering pump.
  • Is level within specification?
E2 CHECK ACCESSORY DRIVE BELT Yes

GO to E3 .

No

INSTALL a new accessory drive belt.

  • Check accessory drive belt tension and condition.
  • Is the accessory drive belt OK?
E3 CHECK POWER STEERING HOSES Yes

GO to E4 .

No

INSTALL new hoses as necessary.

  • Check power steering pressure hoses, power steering gear pressure hoses and power steering return hose for cracks or leaks.
  • Do power steering pressure hose, power steering gear hose and power steering return hose check OK?
E4 CHECK BRAKE PEDAL LINKAGE Yes

GO to E5 .

No

INSTALL new pedal linkage as necessary.

  • Check brake pedal linkage for binding or sticking operation.
  • Does pedal linkage check OK?
E5 CHECK POWER STEERING PUMP SPEED Yes

GO to E6 .

No

SET engine idle speed to specification.

REFER to Powertrain Control/Emissions Diagnosis (PC/ED) manual.

  • Check engine idle speed against specifications.
  • Is engine idle speed OK?
E6 CHECK FOR PLUGGED RETURN HOSE Yes

INSTALL a new power steering return hose.

No

GO to E7 .

  • NOTE: The return hose from the oil cooler to the power steering reservoir has an in-line filter in the hose.
  • Disconnect power steering return hose from power steering fluid cooler and power steering pump reservoir.
  • Pass air through hose from the oil cooler end.
  • Is hose plugged?
E7 CHECK POWER STEERING PUMP FLOW AND RELIEF Yes

INSTALL a new power brake hydro-boost unit.

No

INSTALL a new power steering pump.

  • Test power steering pump for correct flow and relief pressure.
  • Is power steering pump operating correctly?

PINPOINT TEST F: HYDRO-BOOST ERRATIC OPERATION, STICKS, BINDS OR GRABS

Test Step Result / Action to Take
F1 CHECK SUPPLY HOSE Yes

REMOVE obstructions or INSTALL a new hose.

No

GO to F2 .

  • Check for obstructions in power steering return hose and connections between the power steering pump reservoir and between the power steering pump reservoir and the hydro-boost power brake booster.
  • Are there any obstructions?
F2 CHECK BOOSTER OPERATION Yes

System OK.

No

INSTALL a new hydro-boost assembly.

  • Have an assistant check the fluid in the power steering pump reservoir while rapidly applying the brake pedal approximately one inch.
  • Does the fluid show any movement or spouting?

PINPOINT TEST G: HYDRO-BOOST BRAKE SYSTEM OPERATION SUSPECT

Test Step Result / Action to Take
G1 CHECK BASIC OPERATION Yes

Hydro-boost is OK.

No

GO to G2 .

  • Key in OFF position.
  • Press and release brake pedal several times to deplete all hydraulic pressure from the hydro-boost power brake booster.
  • Press and hold brake pedal with light pressure.
  • Key in START position.
  • Does the brake pedal fall slightly and hold, and is less pressure now required to hold brake pedal at the new position?
G2 CHECK FOR HYDRAULIC BRAKE LEAK Yes

GO to G3 .

No

GO to G4 .

  • With engine running, press and release brake pedal several times.
  • Hold brake pedal down with medium pressure, 34-47 Nm (25-35 lb-ft).
  • Does brake pedal move toward floor?
G3 CHECK FOR LEAKS - BRAKE FLUID LINES Yes

COMPLETE master cylinder By-Pass Condition Test in this section.

No

INSTALL new hoses and lines as necessary.

  • Check for leaks at brake lines, including brake master cylinder and brake hose.
  • Do components check OK?
G4 CHECK HYDRO-BOOST CONNECTIONS Yes

GO to G5 .

No

REPAIR or INSTALL new hose and connections as necessary.

  • Clean the hydro-boost power brake booster, power steering pressure hose, power steering gear pressure hose and power steering return hose and connection.
  • Start engine and run at idle.
  • Check hose connections for leakage.
  • Do hose connections check OK?
G5 CHECK FOR HYDRO-BOOST LEAK Yes

GO to G6 .

No

INSTALL a new hydro-boost unit.

  • Engine running at idle speed.
  • CAUTION: Do not hold the brake pedal at 444 Nm (100 lb) force for more than 5 seconds at a time.
  • Apply brake pedal with approximately 444 Nm (100 lb) force and hold.
  • Check hydro-boost unit input seal, housing seal, accumulator seal, piston seal and spool plug seal for leakage.
  • Is hydro-boost unit free of leaks?
G6 CHECK RESERVE RETENTION Yes

Hydro-boost unit is OK.

No

INSTALL a new hydro-boost unit.

  • Engine running at idle speed.
  • CAUTION: Do not hold the brake pedal at 444 Nm (100 lb) force for more than 5 seconds at a time.
  • Charge system to pressure by holding the steering wheel at stop or by pressing the brake pedal with approximately 444 Nm (100 lb) force.
  • Key in OFF position.
  • Wait five seconds.
  • Press brake pedal and observe if there is any power brake reserve.
  • Is there any power brake reserve?
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