Skip the auto shop - Our mechanics make house calls

Q: Brake lights work when vechile is off. They quit when you start it

asked by on

just put a different motor in the 94 gmc it come out of a 89 chevy van first it had a issue of to much gas change temp sensor idle air control vavle throttle position sensor egr vavle knock sensor still the same come to find out change computer it come out of it noiw the issue with the brake lights if vechiles not started they work the minute you start it they quit tail lights work find blinkers work find

My car has 132678 miles.
My car has a manual transmission.

A: There may be a fault in the brake light swi...

There may be a fault in the brake light switch or corrosion crossing a circuit and making the lights work backwards. This switch is usually found on the brake pedal, but a technician with access to a wiring diagram should check the whole circuit for any other issues like loose connections or corrosion that may cause high resistance. Consider having an experienced technician, like one from YourMechanic, come out and take a closer look at the brake lighting to offer a more personal diagnosis.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Turn signal and brake light don't work

The switch in the steering column may be the cause, but a check of the bulbs should be done first, to see if a bulb is at fault. I recommend having a mechanic, like one from YourMechanic, inspect your turn...

Q: Engine making weird noises and revving

With these combination of symptoms, it sounds like your car has a drive belt problem. When it is cold outside, there is more load on the belt on initial startup. In other words, the pulleys are harder to turn. When...

Q: 4.0 lt is very sluggish. no exhaust restriction, fp is ok 45psi, all new tune up.

Hi there. What you're describing may be an underlying fuel pressure concern. Check for any stored codes in the engine computer before replacing any more components. If there are no stored codes, a diagnostic tool will be required to monitor...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...