finding the problem with a car that doesn't always start

Your vehicle has a brake light switch, which does more than turn on the brake lights by closing an electrical circuit. It also plays a role in activating the automatic braking system, activating the vehicle's shift interlock solenoid, and deactivating your cruise control after it has been turned on. If you have a car with a push button ignition, it even helps turn on the car. 

The Service Engine Light Turns On

The brake light switch can actually cause the service engine light to turn on if something is wrong with it. The ABS light can also turn on if there is a problem with the switch. If you hook up a code reader to your vehicle, you may see error code P0504, which specifically calls out the brake light switch as being faulty. You can take your vehicle to a mechanic or to a local auto parts store to read the code for you. It's also possible to buy a code scanner so that you always have it on hand when your engine light turns on. 

The Brake Lights Don't Work Properly

An obvious problem with a brake light switch is that you will not have any brake lights when you press down on the brake pedal. Of course, it can be difficult to troubleshoot this problem when you can't easily see the brake lights, so you'll need someone's help to test them and see what happens. It is worth switching out the light bulb with a new one to ensure that the problem is actually with the switch and not the light bulb.

The other problem is a brake light that constantly stays on. This is a bit easy to identify since you can easily step out of your car and take a look for yourself. This problem is due to the switch having an internal short that causes the circuit to always remain closed, which sends a constant flow of electricity. This can often be a reason why your battery is not working and your car is dead.

The Cruise Control Doesn't Work Properly

Since that brake pedal switch deactivates the cruise control when you press down on the brake pedal, it makes sense that the cruise control won't work properly by tapping on the brakes. If you find yourself having to manually turn off the cruise control, then you know that there has to be a problem with the brake light switch.  

For more information, contact a local automotive repair company.