Skip the auto shop - Our mechanics make house calls

Q: Dimmer light not working - 1991 GMC K2500

asked by on

My dimmer light wasn't working in my 5 speed truck, and the instrument panel lights quit working along with the warning buzzer for turned on lights when you open the door. I am not positive about the buzzer being in this truck, but I’m sure about the panel lights going out. So I took off the dimmer switch to test the wiring. There were 4 wires and the only continual hot lead was the white wire. When I turned on the lights I only had the one white hot lead. When I turned the dimmer knob all the way up, my lower cab lights under the dashboard worked normally. My lights worked well - both the low and high beams. Should there be more than 1 hot lead on the dimmer switch when the lights are off? Should one of the other wires be a hot lead when the lights are on? Do you know what should be hot and what shouldn’t be hot on the wires to the dimmer switch? Are there relays I should be checking? It looks like there is a relay panel above the emergency brake foot pedal with 3 relay box devices.

Hey there, thanks for writing in about your 1991 GMC K2500. You should have power on the white wire, dark green wire, and also the brown wire when the dashboard lights dimmer is turned on. If you need help having this checked, a qualified professional from YourMechanic can come to your car’s location to inspect the light circuitry in order to have this corrected.

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
  1. Home
  2. Questions
  3. Dimmer light not working - 1991 GMC K2500

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Ths car stalls sporadically when the engine warms up - 2000 Toyota Echo

I wish you had told me which red light illuminates. I am going to take a shot at it and guess its the battery light. You may have an alternator related problem. It could be a loose belt, the alternator...

Q: Airbag warning light is on, are the airbags broken?

This concern could be related to a number of different areas of the Supplemental Restraint System (SRS). The weight sensor under the seat may not be reading a correct value. There could be an open or short somewhere in the...

Q: It starts but won't stay running.

Hi There, If the motor will start this means you generally do not have any issues with spark or ignition problems. Typically when a motor struggles to stay running, it is often related to a fuel supply problem. This may...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.