CAR VIBRATES AT HIGH SPEEDS

SYMPTOM SUMMARY
There is a vibration or shimmy at high speeds. The symptom may get worse as the vehicles speed increases and may or may not be present at lower speeds.

USUAL CAUSE The usual cause of a vibration or shimmy at high speed is improper tire balance or damaged tires.

DIAGNOSIS
Perform a careful visual inspection of each tire. Look for damage to the tires such as bulges or exposed steel belts. Inspect the wheels for dents, warpage or missing lug nuts. Check the tire pressure to ensure all tires are inflated evenly and to the correct pressure (check the owner's manual for the correct tire pressure - it should also be marked on the side of the tire). If the tires are in good condition, the most cost effective diagnosis is to have the tires computer spin balanced. This can be done at any tire retailer for a nominal charge. If the problem still persists, further diagnosis on the drive train should be performed. On rear wheel drive vehicles the U-Joints should be inspected. On front wheel drive vehicles, the drive axles and CV Joints should be inspected. Inspect the CV boots for tears or other damage indicating excessive joint wear.

PRECAUTIONS, TIPS, and NOTES Tires contain steel belts that, if exposed, are very sharp and can cut or cause injury to your skin. To prevent possible injury to your hands, do not run your hand over the tire during inspection.

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BRAKE WARNING LIGHT IS ON

SYMPTOM SUMMARY
The red brake warning lamp remains on after the vehicle is started.

USUAL CAUSE
The brake system is equipped with a red brake warning lamp that will illuminate under certain conditions. Some vehicles feature a float located in the master cylinder that will illuminate the brake warning lamp when the fluid level becomes too low. The light will also come on if hydraulic pressure is lost in one of the front or rear brake channels. Usually the proportioning valve contains the circuit that will turn the light on during hydraulic pressure failure. It will also automatically prevent any additional fluid to be routed to the leaking channel. This ensures there is an adequate brake fluid and pressure supply to the working channel. The light usually functions as the parking brake indicator lamp as well.

DIAGNOSIS
The first step in diagnosing this symptom is a visual inspection. Check the brake fluid level in the master cylinder to ensure it is within specifications. If the brake fluid level is low, you will need to inspect the system for leaks. You may refer to the "Brake Fluid Consumption" symptom for further details on the diagnosis of brake fluid loss. Ensure the emergency brake is completely released. On most vehicles, the emergency brake circuit will illuminate the bulb at a different intensity than the fluid level or pressure sensors. If the brakes function normally and have been inspected and found to be leak free, you should suspect a malfunction in the emergency brake light circuit. Apply and release the emergency brake and look for a change in the bulbs intensity. If no change occurs, this further confirms a malfunction in the emergency brake light circuit. This switch is usually located on the emergency brake mechanism and should be inspected for damage.

PRECAUTIONS, TIPS, and NOTES
Always use the proper brake fluid DOT rating when refilling or adding to the brake fluid master cylinder. Do not add more than 1 oz of fluid to the master cylinder without inspecting the system for leaks.

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MASTER CYLINDER IS LOW ON BRAKE FLUID

SYMPTOM SUMMARY
The master cylinder is low on brake fluid or the brake fluid continually goes low.

USUAL CAUSE
It is normal for the master fluid level to decrease slightly as the brake pads wear. As the brake pads wear, the pistons in the caliper extend to compensate for the friction wear. As this occurs, the caliper will store more brake fluid in the caliper cylinder and will decrease the fluid level in the master cylinder.

DIAGNOSIS
You will need to determine whether the fluid level is low in the master cylinder due to a fluid leak or the normal brake pad wear discussed above. A brake inspeciton should be performed to determine the cause. The calipers, wheel cylinders (on drum brakes) will need to be inspected. The brake pads and shoes (if equipped) should be inspected for signs of brake fluid contamination indicating a leak. Inspect the calipers for leaks at the rubber dust boot around the pistons. The dust boot on the wheel cylinder will have to be pulled off slightly to inspect for leaks. Check the hydraulic lines, proportioning valve and flexible hoses for leaks. Inspect the master cylinder where it mounts on the brake boosters for signs of leaks. Loosening the master cylinder retaining bolts and pulling it back slightly, will usually result in detection of a leak if present. If leaking, the fluid will run out of the mating surfaces. In this case, the master cylinder will require replacement. If there are no leaks present and the pads are worn, the most likely cause of the low brake fluid level is worn brake pads.

PRECAUTIONS, TIPS, and NOTES
The brake fluid level should be inspected at every oil change. If servicing the hydraulic system, use caution not to contaminate the system with dirt, debris or water. After the hydraulic system is serviced it will require bleeding. Refer to the manufacturers bleeding procedure to ensure all of the air is purged from the system. Always use the recommended brake fluid DOT rating. This information can be obtained from your owners manual or off the cap on the master cylinder.

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LOUD SQUEAL HEARD WHEN STEERING WHEEL IS TURNED

SYMPTOM SUMMARY
A loud squeal is emitted from under the hood when the steering wheel is turned.

USUAL CAUSE This symptom is usually caused by a loose or worn power steering belt.

DIAGNOSIS
With the help of an assistant, rotate the wheel all the way to the right or left while inspecting the drive belts. If the drive belts slip or squeal, service will be necessary. With the vehicle off, inspect the belts for wear or cracking. Some vehicles utilize a single serpentine belt that drives all of the accessories. These types of belts usually use an automatic tensioner that maintains the proper tension at all times. Inspect the belts for proper alignment to the pullies. A worn tensioner bearing can throw the belt out of alignment, causing abnormal belt wear or breakage.
Vehicles that use conventional "V" belts should be inspected for cracks or glazing. Over time, the inside surface of the V-belt can become glazed which can cause it to slip. A glazed belt will have a shine to it and feel hard and brittle. The tension of the V-belt should have about a 1/2" of deflection between its longest span. Over tightening a V-belt can lead to bearing failure in the driven accessory. Drive belts that are worn should be replaced and properly tensioned.

PRECAUTIONS, TIPS, and NOTES
Some vehicles use automatic tensioners that contain a large spring used to tension the drive belt(s). You should use caution when removing the belt from the tensioner. The tensioner can snap if not carefully held in place causing injury to your hands or arms. Always use caution when working under the hood. Some parts become very hot and can burn if touched. Rotating engine parts should be avoided by your body and loose clothing. Entanglement can cause severe injury.

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THERE IS A LIQUID ON THE FLOORBOARD OF MY CAR

SYMPTOM SUMMARYThere is a liquid present on the floorboard of the vehicle. The fluid may be green or clear and may be more noticeable after operating the heating or air conditioning system.

USUAL CAUSE Water present on the floorboard is usually caused by one of two things. Water is circulated into the passenger compartment through the heater core. The heater core is heated by the engine coolant. Air is then blown over the heater core, by the blower motor when the heater is on, to heat the passenger compartment. If this core develops a leak, it will usually leak into the passenger compartment floorboard. A heater core that has only a pin-hole sized leak, may not be leaking on the floor but may produce a fine mist or oily film that collects on the inside of the windshield. The evaporator core is also located in the same housing as the heater core. During normal air conditioning operation water will condense on the core. This water is normally drained out of the passenger compartment through a evaporator drain hose. The hose connects from the evaporator case inside the vehicle to the exterior of the vehicle at the rear of the engine compartment. If this hose becomes restricted, the water that condenses on the evaporator core will leak into the passenger compartment. This is usually clean water that will evaporate as opposed to coolant that will not evaporate and leave an oily film on the floorboard carpet.

DIAGNOSIS
You should verify the type of leak present. The heater core contains coolant that will feel oily and may have a green color to it. Water from the evaporator core will be clear with no color. Taking a white piece of paper and absorbing some of the fluid may help determine the fluid type.

CORRECTIVE ACTION
The only corrective action for a leak in the heater core is replacement. Do not use radiator stop leak or other sealant products in an attempt to fix a leak in the heater core. If the fluid is clear, the evaporator drain tube may be restricted or plugged. This hose is usually visible at the lower rear of the engine compartment on the right (passenger) side of the vehicle. You can inspect and/or clear the blockage by passing a piece of stiff wire through the end of the hose.

PRECAUTIONS, TIPS, and NOTES
A heater core that is leaking cannot be repaired and must be replaced. On most vehicles, replacing the heater core is an extensive and time-consuming project that may require special tools. The evaporator core that contains the refrigerant (Freon) for the air conditioner may be contained in the same housing as the heater core. On these vehicles, the housing is removed as a single unit and requires the refrigerant to be removed from the air conditioning system using special equipment. You should consult a repair manual specific to your vehicle or consult the advice of a professional technician prior to undertaking this job.

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FRONT END DIPS WHEN I STEP ON THE BRAKES

SYMPTOM SUMMARY
The vehicle dips forward when the brakes are applied.

USUAL CAUSE This symptom is usually caused by misadjusted rear brakes or weak shocks or struts.

DIAGNOSIS The shocks or struts can be tested by bouncing the front of the vehicle several times by placing your body weight on the front bumper. Once the vehicle starts the up and down motion, remove your weight from the front bumper. The up and down bouncing should come to a stop after only one or two additional bounces. If the the vehicle continues to bounce, the front shocks or struts may require replacement. A tire inspection can reveal worn shocks or struts as well. Bumps and dips accross the tread of the tire can indicate failed shocks or struts. If the shocks or struts are in good working order, the rear brake adjustment should be inspected. Inspect the parking brake to make sure it holds. If it does not hold, operate it several times. This will adjust the rear brakes on vehicles with self adjusters. If the parking brake still does not hold, a visual inspection of the brakes will be necessary to determine the cause.

PRECAUTIONS, TIPS, and NOTES Brake drums and rotors become extremely hot after vehicle operation. Use caution when working around hot braking components.

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CAR PULLS WHEN I STEP ON THE BRAKES

SYMPTOM SUMMARY
The vehicle pulls to the right or left when the brakes are applied.

USUAL CAUSE The usual cause of this symptom is contamination on the braking surface or a malfunctioning caliper. It can also be caused by different tire sizes on the right and left wheels. Worn suspension components can also cause this symptom.

DIAGNOSIS
If contamination, such as grease or oil is present on the left side, the vehicle will pull to the right since the left side will not provide the same braking force as the right. A visual inspection is the first step in diagnosing the problem. Perform a visual inspection on both sides of the vehicle. Check the following:

1. Inspect the tires for even tread wear and overall condition. Check to ensure tire inflation is the same and to specifications.

2. Inspect the brake rotors for contamination. On front wheel drive vehicles, inspect the CV boots for tears. If torn, the CV boot can allow the grease to contact the brake rotors.

3. Check the brake pads to ensure they are worn evenly on both sides of the vehicle. If one side is worn excessively, it could be caused by a sticking brake caliper. The brake caliper can slide or the pistons can stick, causing the brake caliper to maintain braking force on the caliper. This might be accompanied by a discolored brake rotor as well. Rotation of the wheels by hand with the vehicle on jackstands should be even on each side. On front wheel drive vehicles, the transmission should be placed in neutral. Ensure the emergency brake is engaged and proper jacking procedures are used. A wheel that requires excessive force to rotate by hand should be investigated further.

4. Inspect the rubber brake hoses that connect to the calipers. A collapsed brake line can expand under pressure, allowing the brake fluid to enter the caliper then collapse trapping the brake fluid in the caliper.

5. With the vehicle jacked up and the tires on, inspect the front end components for excessive wear. With one hand on the front of the tire and one on the wheel, try to turn the wheel right and left (as if in a turn, not rotational). The wheel may be able to be turned to the right or left, but it should be tight and have no free play back and forth. Perform the same test with one hand on the top and one on the bottom of the tire. With your hand on the top, pull out while pushing in with the hand on the bottom. Then do the opposite, pull out on the bottom and in on the top. There should be no play in the wheel. If play is present in both of the above tests, it is usually an indication of a worn wheel bearing. If there is only play from right to left, it is usually an indication of a worn suspension component such as a tie rod end or rack and pinion. Perfoming the test while inspecting the front end will usually reveal the worn component.

PRECAUTIONS, TIPS, and NOTES Brake rotors become extremely hot during braking. Use caution when working on the brakes shortly after vehicle operation. Always refer to manufacturers jacking procedures to prevent damage to the vehicle or injury to yourself.

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