| Diagnosis and Testing Special Tool(s) | | Vacuum Pump 416-D002 (D95L-7559-A) or equivalent | Materials Name Specification High Performance DOT 3 Motor Vehicle Brake Fluid
PM-1-C (US); CPM-1-C (Canada) WSS-M6C62-A Silicone Brake Caliper Grease and Dielectric Compound
XG-3-A ESE-M1C171-A Metal Brake Parts Cleaner
PM-4-A or PM-4-B (US); CPM-4 (Canada) — Principles of Operation Applying the brake pedal uses lever action to push a rod into the brake booster, which through the use of vacuum, boosts the force of the rod and then transmits this force into the master cylinder. This produces hydraulic pressure in the master cylinder. The hydraulic pressure is transmitted by brake fluid through the brake lines to the individual brake calipers or wheel cylinders. The brake calipers or wheel cylinders use hydraulic pressure to apply the pads or shoes. The application of the brake pads or shoes will cause the rotation of the wheels to slow or stop depending on how much brake pressure is applied. The parking brakes carry out the same function except that they are mechanically actuated by a cable that connects only to the rear brakes. Inspection and Verification WARNING:Use of any brake fluid other than the approved DOT 3 will cause permanent damage to brake components and will render the brakes inoperative. Failure to follow these instructions may result in personal injury. WARNING:Carefully read cautionary information on product label. For EMERGENCY MEDICAL INFORMATION seek medical advice. In the USA or Canada on Ford/Motorcraft products call: 1-800-959-3673. For additional information, consult the product Material Safety Data Sheet (MSDS) if available. Failure to follow these instructions may result in personal injury. CAUTION:Brake fluid is harmful to painted and plastic surfaces. If brake fluid is spilled onto a painted or plastic surface, immediately wash it with water. NOTE:The ignition key must be in the ON position when checking the brake fluid level. NOTE:Always check the fluid level in the brake master cylinder reservoir before carrying out the test procedures. If the fluid level is not at the correct level, clean the reservoir cap before removing, then add clean, specified brake fluid. The first indication that something may be wrong in the brake system is a change in the feeling through the brake pedal. The brake warning indicator in the instrument cluster and the brake fluid level in the brake master cylinder reservoir are also indicators of system concerns. If a wheel is locked and the vehicle must be moved, open a bleeder screw at the locked wheel to let out enough fluid to relieve the pressure. Close the bleeder screw. This bleeding operation may release the brakes but will not correct the cause of the concern. If this does not relieve the locked wheel condition, repair the locked components before proceeding. Inspect all hoses and connections. All unused vacuum connectors should be capped. Make sure hoses and their connections are correctly secured and in good condition with no holes, soft or collapsed areas. Road Test The technician should have a thorough knowledge of the brake system operation and accepted general braking guidelines in order to detect any problems. Select a road that is reasonably smooth and level. Gravel or bumpy roads are not suitable because the surface does not allow the tires to grip the road equally. Avoid crowned roads. A key factor in evaluating brake concerns is the deceleration rate. This varies from vehicle to vehicle and with changes in operating conditions. It is evident how well the brakes are working after just a few applications. For low or spongy brake pedal concerns: - check and, if necessary, refill the brake master cylinder reservoir.
- bleed the brake system and retest the brake pedal feel.
- if the brake pedal is still low or feels spongy, check the brake pedal mounting for looseness and correct installation. Check the brake booster and the brake master cylinder for loose mounting. Correct as necessary and retest the system for normal operation.
For a slow or incomplete brake pedal return concern: - inspect for binding, damage, correct installation or interference at the brake pedal.
- check the brake booster for binding, damage and correct installation.
Brake Pads NOTE:New brake pads are not required if the friction material properties are within the guidelines. New brake pads are not required when the brake discs are machined. - Remove the brake pads. Refer to Section 206-03 Front Disc Brake for front disc brakes or Section 206-04 Rear Disc Brake for rear disc brakes.
- Inspect and measure the thickness of the brake pad friction material.
- Install new brake pads if the thickness of the friction material is less than 3 mm (0.118 in). - Compare all 4 front or rear pads for uneven wear. Install new brake pads if the thickness of the friction material varies from pad to pad by more than 2 mm (0.079 in). - Install new brake pads if there are missing pieces or cracks in the lining through the backing plate. - If the friction material shows taper wear (for example: the thickness varies by more than 3 mm [0.118 in] any direction), or if the pads show uneven wear (2 mm [0.079 in] difference between the inboard and the outboard pad), verify the caliper guide pins are functioning correctly. Refer to Brake Caliper Guide Pins in this section. Brake Discs CAUTION:Using an impact tool without a torque socket will lead to unevenly tightened wheel nuts. This causes brake disc on-vehicle lateral runout and brake roughness. NOTE:It is generally not necessary to install new brake discs to address noise issues. - Remove the brake discs. Refer to Section 206-03 Front Disc Brake for front disc brakes or Section 206-04 Rear Disc Brake for rear disc brakes.
- Inspect the brake discs and measure the brake disc thickness in a minimum of 4 places around the circumference of the brake disc. Record the measurements.
- Install new brake discs if cracked. - Machine the brake discs if the diagnosis has revealed vibration in the steering wheel, seat, or pedal while braking. Heavily scored brake discs, similar to that caused by pads worn down to the backing plate, should also be machined. In order to machine, discs must be above the minimum thickness to machine specification. Refer to Section 206-03 Front Disc Brake for front disc brakes or Section 206-04 Rear Disc Brake for rear disc brakes. Brake Caliper Inspect the brake calipers for the following: - Brake fluid leaks
- Boots and seals for tears or cracks
- Caliper piston for binding and corrosion
- Guide pins for correct operation. Refer to Brake Caliper Guide Pins in this section
Brake Caliper Guide Pins CAUTION:Do not use power tools for caliper guide pin bore cleaning. The guide pins should slide with a reasonable amount of hand force. If the brake pads show taper wear or if the guide pins are difficult to move, then carry out the following steps. NOTE:If a guide pin kit is not available, install a new caliper assembly. - Disassemble the guide pins. Refer to Section 206-03 Front Disc Brake for front disc brakes or Section 206-04 Rear Disc Brake for rear disc brakes.
- Use a wire brush, rolled-up sandpaper, or emery cloth to remove all corrosion and foreign material from the caliper guide pin bores. Clean any remaining foreign material from the bores with brake parts cleaner and compressed air.
- Install new brake pads if the lining is not within specifications. Refer to Section 206-03 Front Disc Brake for front disc brakes or Section 206-04 Rear Disc Brake for rear disc brakes.
- Assemble the caliper guide pins using new caliper seals, boots and guide pins. Use an ample amount of silicone grease to lubricate the bores and guide pins.
Brake Hoses and Tubes CAUTION:Never use copper tubing. It is subject to fatigue, cracking, and corrosion, which could result in brake tube failure. - Double-wall steel tubing is used throughout the brake hydraulic system. All brake tube fittings must be correctly double-flared to provide strong, leakproof connections. When bending tubing to fit underbody or rear axle contours, be careful not to kink or crack the tube.
- If a section of brake tube is damaged, the entire section must be installed new with a tube of the same type, size, shape and length.
- When installing the hydraulic brake tubing, hoses or connectors, tighten all connections to specification. After installation, bleed the brake system. Refer to Brake System Bleeding in this section.
- The wet appearance of the outer cover of rubber brake hoses is called sweating. This is a normal condition for neoprene rayon-braided hose and is not a sign of leakage or cause to install a new hose.
Install a new flexible brake hose if the hose shows signs of softening, cracking or other damage. When installing a new brake hose, position the hose to avoid contact with other vehicle components. Non-Pressure Leaks The only part of the brake system that could have a brake fluid loss, that does not appear when the system is under pressure, is the brake master cylinder reservoir under the following conditions: - Missing or poorly-fitted brake master cylinder filler cap
- Punctured or otherwise damaged brake master cylinder reservoir
- Missing or damaged brake master cylinder filler cap gasket
- Missing, damaged, or poorly-fitted sealing grommets between the brake master cylinder and the brake master cylinder reservoir
The brake master cylinder reservoir grommets are not repairable and must be installed new as part of a new brake master cylinder reservoir. Brake Master Cylinder — Normal Conditions The following conditions are considered normal and are not indications that the brake master cylinder is in need of service. Condition 1: During normal operation of the brake master cylinder, the fluid level in the brake master cylinder reservoir falls during brake application and rises during release. The net fluid level (such as after brake application and release) remains unchanged. Condition 2: A trace of brake fluid exists on the booster shell below the master cylinder mounting flange. This results from the normal lubricating action of the master cylinder bore and seal. Condition 3: Fluid level decreases with pad wear. Brake Master Cylinder — Abnormal Conditions Changes in brake pedal feel or travel are indicators that something could be wrong in the brake system. GO to Symptom Chart for abnormal condition diagnosis. Parking Brake Check the operation of the parking brake system with the vehicle on a hoist and the parking brake control fully released. Check for any damaged cables and install new components as necessary. Check the rear brake adjustment or carry out the brake system diagnosis. Refer to Section 206-05 Parking Brake and Actuation. Symptom Chart Symptom Chart | Symptom | Possible Sources | Action | | The red brake warning indicator is always on | * Parking brake not fully released | * RELEASE the parking brake. | | * Low brake fluid level | * FILL the brake fluid reservoir to the MAX line. INSPECT the system for leaks. REPAIR as necessary. | | * Brake warning indicator circuit malfunction | * | | * Brake master cylinder inoperative | * CARRY OUT the Brake Master Cylinder component test. REFER to Component Tests in this section. | | Red brake warning indicator inoperative | * Circuitry * Bulb * Instrument cluster | * | | The brakes pull or drift | * Tire air pressure | * CHECK the tires for uneven or excessive wear and correct inflation. | | * Brake pads | * CHECK the brake pads for uneven taper or excessive wear. REPAIR as necessary. | | * Brake components | * CHECK the brake tubes, hoses, discs and the hubs for damage. REPAIR or INSTALL new components as necessary. | | * Suspension component | * INSTALL new suspension components as necessary. | | * Wheel alignment | * | | Brake pedal goes down fast | * Brake fluid level | * INSPECT the system for leaks and REPAIR as necessary. FILL the brake master cylinder reservoir. BLEED the system. REFER to Brake System Bleeding in this section. | | * Air in system | * INSPECT the system for leaks and REPAIR as necessary. BLEED the system. REFER to Brake System Bleeding in this section. | | * Brake master cylinder | * CARRY OUT the Brake Master Cylinder component test. REFER to Component Tests in this section. | | The brake pedal eases down slowly | * Air in system | * INSPECT the system for leaks and REPAIR as necessary. BLEED the system. REFER to Brake System Bleeding in this section. | | * Brake master cylinder | * CARRY OUT the Brake Master Cylinder component test. REFER to Component Tests in this section. | | Brake lockup under light brake pedal force | * Brake pads | * CHECK the brake pads for uneven taper or excessive wear. REPAIR as necessary. | | * Brake component | * CHECK the brake components for correct operation. REPAIR as necessary. | | * Parking brake component | * | | * Anti-lock brake system (ABS) | * | | Excessive/erratic brake pedal travel | * Leak in hydraulic system * Air in system * Disc brake caliper | * INSPECT the system for leaks and REPAIR as necessary. BLEED the system. REFER to Brake System Bleeding in this section. | | * Brake master cylinder | * CARRY OUT the Brake Master Cylinder component test. REFER to Component Tests in this section. | | * Brake pads | * CHECK the brake pads for excessive wear. REPAIR as necessary. | | * Brake pedal | * CHECK the brake pedal for binding or obstructions. REPAIR as necessary. | | Brakes drag | * Parking brake component | * | | * Brake caliper guide pins | * | | * Disc brake caliper | * | | * Brake booster | * CARRY OUT the Brake Booster component test. REFER to Component Tests in this section. | | * Brake master cylinder | * CARRY OUT the Brake Master Cylinder component test. REFER to Component Tests in this section. | | Excessive brake pedal effort | * Brake booster | * CARRY OUT the Brake Booster component test. REFER to Component Tests in this section. | | * Brake booster check valve | * CARRY OUT the Check Valve component test. REFER to Component Tests in this section. | | * Brake booster manifold vacuum hose | * REROUTE, REPAIR, or INSTALL new components as necessary. | | Rattling noise | * Caliper mounting bolts loose | * CHECK the caliper bolts. TIGHTEN to specifications. | | * Damaged or worn caliper guide pins or retainers | * CHECK the caliper guide pins and retainers for lubrication and correct operation. LUBRICATE or INSTALL new components as necessary. REFER to Brake Caliper Guide Pins in this section. | | * Missing or damaged anti-rattle clips or springs | * | | * Loose brake disc shield | * INSPECT the disc brake shields. REPAIR as necessary. | | Clicking noise — with brakes applied and anti-lock brake system (ABS) engaged | * ABS hydraulic control unit | * Acceptable condition. | | Squealing noise — occurs on first (morning) brake application | * Brake pads | * Acceptable condition. Caused by humidity and low brake pad temperature. | | Squealing noise — a continuous squeal | * Brake pads worn below minimum thickness | * INSPECT the brake pads for excessive wear, taper wear, or uneven wear. VERIFY the brake pads are within minimum specifications. REFER to Specifications in this section. | | Squealing noise — an intermittent squeal brought on by cold, heat, water, mud or snow | * Brake pads | * Acceptable condition. | | Groaning noise — occurs at low speeds with the brake lightly applied (creeping) | * Brake pads | * Acceptable condition. | | Grinding noise — continuous | * Brake pads worn below minimum thickness | * INSPECT the brake pads, brake discs, and attaching hardware for damage. VERIFY the brake pads are within minimum specifications. REFER to Specifications in this section. | | Moaning noise | * Brake linings contaminated with grease or oil | * | | Vibration when brakes are applied | * Uneven brake pad wear * Brake disc pad transfer * Brake disc * Brake drum * Suspension components | * COMPLETE the brake system inspection described in Inspection and Verification in this section. * | | Brake vibration/shudder — occurs when the brake pedal is released | * Brake caliper guide pins | * INSPECT the brake caliper guide pins for correct operation. REFER to Brake Caliper Guide Pins in this section. | | * Brake drag | * INSPECT the brake pads for premature wear. REPAIR or INSTALL a new caliper or wheel cylinder as necessary. REFER to Section 206-03 Front Disc Brake for front disc brakes or Section 206-04 Rear Disc Brake for rear disc brakes. | Pinpoint Tests Pinpoint Test A: Vibration When Brakes Are Applied Normal Operation During moderate to heavy braking, noise from the hydraulic control unit (HCU) and pulsation in the brake pedal can be observed. Pedal pulsation coupled with noise during heavy braking or on loose gravel, bumps, or wet or snowy surfaces is acceptable and indicates correct functioning of the ABS system. Pedal pulsation alone or steering wheel nibble (frequency is proportional to the vehicle speed) indicates a concern with a brake or suspension component. Possible Causes - Uneven brake pad wear
- Brake disc pad transfer
- Brake disc
- Suspension components
| PINPOINT TEST A : VIBRATION WHEN BRAKES ARE APPLIED | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | A1: CHECK OASIS FOR TSBS | | | 1 Check the On-Line Automotive Service Information System (OASIS) and Technical Service Bulletins (TSBs) for applicable brake concerns. | | | Is there applicable information available on OASIS or in a TSB? Yes REFER to OASIS or the TSB. CARRY OUT any necessary repairs that are indicated by OASIS or the TSB. If the concern is still present, GO to A2. . No | | A2: ROAD TEST THE VEHICLE — LIGHT BRAKING | | | 1 | | | 2 Road test the vehicle. Warm the brakes by slowing the vehicle from 80 to 32 km/h (50 to 20 mph) using light brake force. At highway speeds of 89-97 km/h (55-60 mph), apply the brake using light pedal force. | | | Is there a vibration/shudder felt in the steering wheel, seat or brake pedal? Yes No | | A3: ROAD TEST THE VEHICLE — MODERATE TO HEAVY BRAKING | | | 1 Road test the vehicle. At highway speeds of 89-97 km/h (55-60 mph), apply the brakes using moderate to heavy pedal force. | | | Is there a vibration/shudder? Yes No The concern is not present at this time. | | A4: NORMAL ACTUATION OF THE ABS SYSTEM DIAGNOSIS | | | 1 During moderate to heavy braking, noise from the hydraulic control unit (HCU) and pulsation in the brake pedal can be observed. Pedal pulsation coupled with noise during heavy braking or on loose gravel, bumps, or wet or snowy surfaces is acceptable and indicates correct functioning of the ABS system. Pedal pulsation or steering wheel nibble (frequency is proportional to the vehicle speed) indicates a concern with a brake or suspension component. | | | Is the vibration/shudder vehicle speed sensitive? Yes No The concern is not present at this time. | | A5: CHECK THE FRONT SUSPENSION | | | 1 | | | Are all the suspension components in satisfactory condition? Yes No REPAIR or INSTALL new components as necessary. REFER to Section 204-01 Front Suspension. TEST the system for normal operation. | | A6: RESURFACE THE FRONT BRAKE DISCS | CAUTION:Do not use a bench lathe to machine the brake discs. | NOTE:Follow the manufacturer's instructions to machine the brake discs. After machining, make sure the brake disc meets the thickness specification. Refer to Section 206-03 Front Disc Brake. | | | 1 Resurface the front brake discs. | | | 2 Road test the vehicle. | | | Is the vibration/shudder present? Yes No The concern is not present at this time. | | A7: CHECK THE REAR SUSPENSION | | | 1 | | | Are all the suspension components in satisfactory condition? Yes No REPAIR or INSTALL new components as necessary. REFER to Section 204-02 Rear Suspension. TEST the system for normal operation. | | A8: RESURFACE THE REAR BRAKE DISCS | CAUTION:Do not use a bench lathe to machine the brake discs. | NOTE:Follow the manufacturer's instructions to machine the brake discs. After machining, make sure the brake disc meets the thickness specification. Refer toSection 206-04 Rear Disc Brake. | | | 1 Resurface the rear brake discs. | | | 2 Road test the vehicle. | | | Is the vibration/shudder present? Yes No The concern is not present at this time. | Component Tests Brake Booster — Operation Check - Inspect all vacuum hoses and connections. All unused vacuum connections must be capped. Hoses and their connections must be correctly secured and in good condition with no holes, cracks or collapsed areas.
- Check the brake hydraulic system for leaks or insufficient brake fluid. Repair as necessary.
- With the engine OFF, place the transaxle in PARK (A/T) or NEUTRAL (M/T) and apply the parking brake.
-
NOTE:If the power brake booster is noisy when the brakes are applied, a new component must be installed. Apply and hold the brake pedal several times to exhaust all of the vacuum reserve from the system. - Apply and hold the brake pedal.
- Start the engine. If the vacuum system is operating, the brake pedal will move downward slightly under constant foot pressure. If no movement occurs, the power brake booster system is not functioning. Turn the engine off.
- Remove the vacuum hose from the power brake booster.
- Place the transaxle in PARK (A/T) or NEUTRAL (M/T) and apply the parking brake. Start the engine. Manifold vacuum should be available from the vacuum booster hose. If manifold vacuum is not available, inspect all of the hoses and hose connections. Repair as necessary.
- Connect the vacuum booster hose and run the engine at fast idle for 10 seconds.
- Turn off the engine and let the vehicle stand for 10 minutes.
- Apply the brake pedal with approximately 89 N (18 lb) of force. The brake pedal feel should be the same as normal power-assisted brake operation for at least one brake pedal application. If the brake pedal feel is normal, the power brake booster is OK. If the brake pedal feels hard, continue with the test.
- Remove the vacuum booster hose from the power brake booster. Apply 57.3 kPa (17 in-Hg) of vacuum to the vacuum booster hose. If the vacuum does not leak off after 10 minutes, install a new power brake booster. If the vacuum does leak off, install a new check valve and/or new vacuum booster hoses.
Check Valve - Remove the vacuum booster hose from the power brake booster.
- Apply 57.3 kPa (17 in-Hg) of vacuum to the vacuum booster hose. If the vacuum does not leak off after 10 minutes, the check valve is OK. Otherwise, install a new check valve.
Brake Master Cylinder Tests Brake Master Cylinder — Bypass Condition - Check the brake hydraulic system for leaks or insufficient brake fluid. Repair as necessary.
Brake Master Cylinder — Non-Pressure External Leaks A low brake fluid level in the brake master cylinder reservoir may be caused by the following non-pressure external leaks: Type 1: An external leak may exist at the brake master cylinder filler cap due to incorrect position of the cap, cap gasket or cap gasket deterioration. Repair or install new components as necessary. Type 2: An external leak may exist at the brake master cylinder mounting flange due to internal seal failure. Repair or install a new brake master cylinder. Refer to Section 206-06 Hydraulic Brake Actuation. Type 3: An external leak may exist at the base of the brake master cylinder reservoir due to deteriorated reservoir mounting seals. Repair or install a new brake master cylinder. Refer to Section 206-06 Hydraulic Brake Actuation. Brake Master Cylinder — Compensator Port The purpose of the compensator ports in the brake master cylinder is to: - supply additional brake fluid from the brake master cylinder reservoir needed by the brake system due to brake lining wear.
- allow brake fluid to return to the brake master cylinder reservoir when the brakes are released. The returning brake fluid creates a slight turbulence in the brake master cylinder reservoir. This is a normal condition and indicates that the compensator ports are not clogged.
Clogged compensator ports may cause the brakes to hang up or not fully release. If clogged compensator ports are suspected, proceed as follows: - With the brakes released, attempt to rotate each wheel. If an excessive amount of brake drag exists, continue with the test. If an excessive amount of brake drag exists at only one wheel, it indicates a possible seized brake disc caliper, brake wheel cylinder, or parking brake component. Repair or install new components as necessary.
- Check the brake stoplamp switch adjustment and the brake pedal free play to verify that the brake pedal is not partially applied.
- Loosen the nuts attaching the brake master cylinder to the power brake booster and pull the brake master cylinder away from the power brake booster.
- Repeat Steps 1 and 2. If the brake drag disappears, the power brake booster is binding and a new one must be installed. Refer to Section 206-07 Power Brake Actuation. If the brake drag continues, the brake master cylinder is binding and a new one must be installed. Refer to Section 206-06 Hydraulic Brake Actuation.
|
