Inspection and Verification
Inspection and VerificationWARNING: 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 or plastic surfaces. Do not spill brake fluid onto painted or plastic surfaces. If spilled, wipe up immediately.
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.
NOTE: Prior to carrying out any diagnosis, make sure the red brake warning indicator is functional. Refer to Instrument panel, gauges and Warning Indicators.
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 the hoses and connections. All unused vacuum connectors should be capped. Make sure the hoses and their connections are correctly secured and in good condition with no holes, or 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 including the brake on/off (BOO) switch and the speed control deactivation switch.
^ check the brake booster for binding, damage and correct installation.
Brake Pads
NOTE: It is not necessary to install new brake pads if the friction material properties are within the specifications. It is also not necessary to install new brake pads when the brake discs are machined.
^ Remove the brake pads.
^ 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 3.0 mm (0.118 inch) Refer to front disc brakes or rear disc brakes.
- 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 2.0 mm (0.079 inch). Refer to front disc brakes or rear disc brakes.
- Install new brake pads if there are missing chunks or cracks in the lining through to the backing plate. Refer to front disc brakes or for rear disc brakes.
- If the friction material shows taper wear (i.e. the thickness varies by more than 3.0 mm [0.118 inch] in any direction) verify the caliper guide pins are functioning correctly. Refer to Brake Caliper Guide Pins.
Brake Discs
CAUTION: Using an impact tool without a torque socket will lead to unevenly tightened lug 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 brake noise concerns.
^ Remove the brake disc. Refer to front disc brakes or 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 any thickness measurement is less than the minimum specification. Refer to the front disc brakes or rear disc brakes.
- Install new brake discs if cracked. Refer to the front disc brakes or rear disc brakes.
- 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, the thickness of the discs must be greater than the minimum thickness to machine specification. Refer to front disc brakes or 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.)
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 the guide pins are difficult to move, carry out the following steps:
NOTE: If a guide pin kit is not available, install a new brake caliper assembly.
^ Disassemble the guide pins. Refer to front disc brakes or 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 specification. Refer to front disc brakes or rear disc brakes.
^ Assemble the caliper guide pins using new caliper seals, boots and guide pins. Use an ample amount of grease to lubricate the bores and guide pins.
Brake Tubes and Hoses
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 the underbody or rear axle contours, be careful not to kink or crack the tube.
^ If a section of the 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.
^ The wet appearance on 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 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) will remain 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: The fluid level decreases with pad wear.
Brake Master Cylinder - Abnormal Conditions
Changes in the brake pedal feel or travel are indicators that something could be wrong in the brake system. GO to Symptom Chart for abnormal condition diagnosis. Symptom Related Diagnostic Procedures
Brake Booster
Inspect the brake booster for the following:
^ Excessive corrosion or damage
^ Vacuum connections for leakage
^ Vacuum hoses for kinks or leakage
^ Brake booster check valve for correct operation
Changes in the brake pedal feel or travel are indicators that something could be wrong in the brake system. GO to Symptom Chart for abnormal condition diagnosis. Symptom Related Diagnostic Procedures
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.
Visual Inspection Chart
Visual Inspection Chart:
For low or spongy brake pedal concerns:
^ check the brake system for fluid leaks, repair as necessary.
^ 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 spongy, check the wheel bearings. Refer to Vehicle/Testing and Inspection.
For a slow or incomplete brake pedal return concern:
^ inspect for binding, damage, correct installation or interference at the brake pedal.
^ check the power brake booster for binding, damage and correct installation.
Adjustable Pedals With Memory Feature
1. Verify the customer concern.
2. Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart
Visual Inspection Chart:
3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
4. NOTE: Make sure to use the latest scan tool software release.
If the cause is not visually evident, connect the scan tool to the data link connector (DLC).
5. NOTE: The vehicle communication module (VCM) LED prove out confirms power and ground from the DLC are provided to the VCM.
If the scan tool does not communicate with the VCM:
^ check the VCM connection to the vehicle.
^ check the scan tool connection to the VCM.
^ Refer to, Information Bus (Module Communications Network), to diagnose no communication with the scan tool.
6. If the scan tool does not communicate with the vehicle:
^ verify the ignition key is in the ON position.
^ verify the scan tool operation with a known good vehicle.
^ refer to to diagnose no response from the powertrain control module (PCM).
7. Carry out the network test.
^ If the scan tool responds with no communication for one or more modules, refer to Information Bus.
^ If the network test passes, retrieve and record continuous memory diagnostic trouble codes (DTCs).
8. Clear the continuous DTCs and carry out the self-test diagnostics for the anti-lock brake system (ABS) module.
9. If the DTCs retrieved are related to the concern, go to Anti-Lock Brake System (ABS) Module Diagnostic Trouble Code (DTC) Chart. For all other DTCs, refer to Body Control Systems (Multifunction Electronic Control Module). Diagnostic Trouble Code Tests and Associated Procedures
10. If no DTCs related to the concern are retrieved, GO to Symptom Chart. Symptom Related Diagnostic Procedures