Fix It

A brake light switch, located on a bracket mounted directly in front of the brake pedal arm, controls your 1993 Nissan Quests brake lights. As the pedal arm pushes forward from the force of you stepping on the brakes, it depresses the switch and activates the brake lights. When the switch short circuits, it will either leave the lights always on or always off. In order to get the lights off, and return them to normal functionality, youll need to replace the faulty brake light switch. If you have mechanical aptitude and 25 minutes of time on your hands, you can fix this problem.

Instructions

1

Open the Quests front door. Adjust the drivers seat as far back as it will go in order to provide yourself with sufficient room to access the under-dash area.

2

Shine the work light in the drivers foot well so it illuminates the area at the top of the brake pedal arm. Retract the retaining tab on the brake light wiring pigtail with your thumb while gripping the pigtail with your foinger. Pull the pigtail off the brake light switch.

3

Unbolt the faulty brake light switch from the mounting bracket using a box wrench. Discard the faulty brake light switch.

4

Set the new brake light switch into the bracket. Bolt it in with the box wrench. Plug the wiring pigtail into the new brake light switch by hand.

5

Depress the brake pedal and have your helper verify the brake lights work before driving your Nissan Quest.

The Ford F150 is a series of 3/4 ton pickup trucks that Ford has manufactured since 1975, and an anti-lock braking system, or ABS, has been standard on the F150 since 1987. The driver in a vehicle with an ABS normally controls the braking force that the wheels receive. In an emergency stop, however, the ABS module controls the brakes to each wheel depending on the speed of the wheel. The ABS module is part of the hydraulic control unit, or HCU, located in the engine compartment under the air cleaner.

Instructions

1

Disconnect the cable to the negative battery terminal with a socket wrench to prevent an electrical discharge during the procedure. Remove the air cleaner from the engine.

2

Remove the four fittings for the brake lines with a socket wrench, and detach the brake lines from the HCU. Disconnect the electrical connector from the HCU. Remove the mounting bolts for the HCU, and disconnect the HCU from its bracket.

3

Disconnect the electrical connector from the ABS module. Remove the retaining screws from the ABS module, and disconnect the ABS module from the HCU.

4

Install the new ABS module to the HCU, and tighten the retaining screws to 27 inch-pounds with a torque wrench. Attach the electrical connector to the ABS module.

5

Mount the HCU to its bracket, and tighten the mounting bolts to 80 inch-pounds with a torque wrench. Install the HCU bracket to the frame of the vehicle, and tighten the bracket mounting bolts to 18 foot-pounds. Connect the brake lines to the HCU, and tighten the fittings to 13 foot-pounds.

6

Connect the air cleaner with a socket wrench. Attach the cable for the negative battery terminal.

It is important to keep your vehicles brake lights functioning well. Brake lights serve as a guide to the driver behind you to brake when you are slowing your car down. Malfunctioning brake lights could cause accidents on the road. Fixing the car brake lights usually involves changing the malfunctioning light bulb.

Instructions

1

Park your vehicle and turn off the ignition. Open the vehicles trunk and access the brake light assembly and remove the red and yellow plastic cover of the brake lights by unscrewing it using the Phillips-head screwdriver in order to access the light bulb. Set aside the screws as it will be needed later on.

2

Locate the brake light bulb. It is usually the center bulb of three bulbs located in the area. Unscrew the brake light bulb by pushing it slightly and turning it counterclockwise at the same time. Set it aside.

3

Clean the area where you removed the bulb with a dry rag. You can also use a steel brush if there is accumulated dirt on the socket. The accumulated dirt can sometimes be the cause of the malfunctioning brake light.

4

Install a new light bulb on the socket by pushing it slightly and twisting it in a clockwise direction. Make sure the bulb is aligned well and screwed in evenly.

5

Check the light bulb to ensure it works by turning on the car and asking someone to push on the brake pedal while you go to the back of the vehicle to see if it lights up.

6

Reattach the plastic cover by inserting the screws in the designated holes and tightening the screws, turning clockwise, using the Phillips-head screwdriver. Put back the brake light assembly at the back of the vehicles trunk.

7

Remove the brake light cover on the vehicles other side and follow steps 2 to 6 to replace the light bulb.

As thick and sturdy as they are, youd think that brake rotors would outlast the entire car. However, those rotors are thick for a reason: They are subject to some of the harshest and most demanding conditions imaginable. Operating under extreme temperatures, mechanical stress and even chemical assault, even the best rotor will eventually score, warp or crack and require some sort of machine work or replacement.

Normal Stresses

Rotors and drums exist to act as a friction surface for the pads to press against, meaning that at some point theyll have to turn several thousand pounds of forward momentum into thermal energy. The pads need to be almost as strong as the rotors to deal with the thermal and shearing stresses involved with braking, which is no mean feat when the rotors are made of hardened steel. Over time, the hard pad material will begin to eat the softer parts of the rotor surface, sometimes wearing it down evenly and other times leaving grooves on the surface.

Warpage

Warped rotors and drums are a result not of rapid heating, as conventional wisdom may have it, but of uneven cooling. Overusing the brakes will overheat the rotors, possibly to the point of glowing red or white hot. At these temperatures, metal acts more like a very slowly flowing liquid than a solid, so it may not assume the same shape once it cools down. Certain parts of the rotor will inevitably cool and contract a little faster than others, pulling some parts of the material in while other parts remain stationary. This causes warpage or "runout," which is a waviness in the rotor that causes brake pedal pulsation afterward.

Normal Resurfacing Conditions

Resurfacing is usually done with a lathe. The rotor goes on a lathe, and a cutting head passes over it to eliminate ridges and waviness. You dont necessarily have to resurface rotors during a pad change, since the rotors are far harder and should, by nature, outlive the pads. Rotors vary in terms of allowance for groove depth, as some rotor faces might be thicker than others. The only way to know for sure is to check your manufacturer recommendations regarding acceptable runout and groove depth. General Motors, for instance, allows for a fairly deep scoring of 1.5 mm before requiring machine work (AA1 Car Library, Understanding Brake Rotor Service). The rule of thumb is that grooves deep enough to catch a fingernail warrant some resurfacing.

Special Conditions

Oddly enough, there is some logic in putting off machine work until the manufacturer requires it. One of the oldest tricks in racing is to use a very thick rotor or drum, and then intentionally score it on a lathe to create a sharply grooves surface. Those deep grooves will increase the rotors surface area; once the pads bed in and conform to the rotor, they can provide significantly more clamping force than they would with a perfectly flat surface.

While no ones suggesting that you engage in any such idiocy with your street car and stock-thickness rotors, its something to bear in mind when considering a pad change without resurfacing. Until the pads bed in and conform to the shape of an un-machined rotor, their reduced contact area guarantees that the new pads will provide less initial stopping power than old pads with the same rotors.

The F150 is Fords full-size 3/4-ton pickup truck, which has been in production since 1975. All versions of the 2001 F150 have an anti-lock braking system, or ABS, as a standard feature. An ABS uses a brake controller, or control module, to determine the braking force that each wheel receives. The brake control module reduces the braking power to a wheel when that wheel moves more slowly than the other wheels. The procedure for installing a brake control module is similar for all F150 trucks made from 2001 to 2006.

Instructions

1

Remove the cable from the negative battery terminal with a socket wrench to prevent an electrical discharge during the procedure. Turn the vents in the center instrument panel inward, and hold the panel by the vents. Pull the center instrument panel outward.

2

Disconnect the upper cover from the steering column with a socket wrench. Turn off the selector switch for the bi-fuel tank, if your vehicle is so equipped. Remove the screws from the center instrument panel, and detach the electrical connector for the panel. Remove the instrument panel from the vehicle.

3

Detach the headlamp switch with a thin pry tool, and disconnect the electrical connectors for the headlamp switch. Unplug the electrical connector for the ABS control module, and remove the bolts from the module with a socket wrench. Detach the ABS control module from the vehicle.

4

Install the new ABS control module, and fasten the bolts to the module with a socket wrench. Attach the electrical connector to the ABS control module. Connect the electrical connector for the headlamp switch, and install the switch.

5

Mount the center instrument panel to the vehicle, and attach the electrical connector to the panel. Fasten the mounting screws for the center instrument panel with a socket wrench. Turn on the bi-fuel tank selector switch, and install the upper cover for the steering column.

6

Connect the cable to the negative battery terminal with a socket wrench.

For most people, a "bad" brake rotor is one with a few scratches and grooves in the surface that cut into the pad, or one thats wavy and warped. But theres a lot more going on with your brake rotors than you might see on the surface -- and even thats bad enough as it is.

What is a "Bad" Rotor?

A lot of things can go wrong with a brake rotor. Most obvious are mechanical faults like grooves in the rotor caused by harder particulates in the pad material, cracks in the rotor and waviness or warping in the rotor surface. A front brake rotor must regularly absorb about 30 to 35 percent of all of the energy that goes into moving your car, which creates a lot of heat. Heat, among other things, causes the rotors metal to expand; when the metal cools and contracts, certain zones in the metal will cool faster than others. The uneven cooling pull those zones in different directions, causing the rotor surface to warp and become wavy. Extreme heating can also affect the metals crystalline structure, causing even bigger long-term problems.

Grooved Rotors

All brake rotors that arent brand-new exhibit a certain amount of grooving on the rotor surface. When the grooves are microscopically small, the peaks between the grooves will cut into the brake pad material. Simultaneously, the harder particles in the pad will resist this cutting and abrade the sides of those grooves. Eventually, the grooves will get large enough to be visible and cut large, matching grooves in the pad. So, its not a matter of if the grooved rotor will cut into your pad -- and vice versa -- but rather how far and how much the pads will deepen those grooves. If the rotors dont exhibit grooves deep or sharp enough to catch a fingernail, then you can replace the pads without machine-work or replacement. You can put new pads on a deeply-grooved rotor, but bear in mind that a) it will take some time for the pads to "bed in" and conform to the grooves in the rotor, b) while bedding in, the pads will rapidly accelerate groove widening and c) grooves create weak points in the rotor, increasing the odds that it will crack or shatter.

Warping

A warped rotor could easily eat your new pads alive, and may damage other, more expensive parts in the brake system. This is particularly true for some cars with antilock braking systems. An ABS system works by boosting or dropping brake pressure to each wheel. If the crests of the waves in your rotor are further apart than the pad is long, then the entire pad will drop in between the waves. When the crests come along, theyll shove backward on the pad, creating tiny fluid pressure fluctuations in the brake lines. These oscillations can damage the antilock brake pressure modulator, which costs far more to replace than itll cost you to have the rotors machined flat. So, if your rotors are warped, new rotors are advisable, particularly since new rotors arent usually much more expensive than machining. And, after machining, youll wind up with thinner rotors that are more prone to overheating and structural failure.

Material Changes

This little-known, but endemic, problem has both plagued and bewildered brake mechanics for a century or more. Long ago, mechanics noticed that, after the rotors for warpage or overheating, cars would often roll back into the shop when the rotors re-warped a few months later. And the re-warping problem has existed as alternately a puzzle or a myth -- depending upon who you asked -- since then. But, fairly recently, engineers have discovered that, following an episode of extreme overheating, the areas of the rotor that got the hottest would change in crystalline structure from the normal ferrite structure to the far harder cementite. Cementite, also known as iron carbide, is much like a ceramic and has far different properties in terms of hardness, abrasiveness and thermal conductivity. Think of chunks of oak floating in frozen ice cream, and youve got the right idea. Once these cementite spots form and penetrate the rotor surface to more than a few nanometers, the rotor is shot and will quickly self-destruct.