How can I repair a defective tail light? - 2002 Cadillac Deville

Defective light switch.

IF THE TAIL LIGHTS ARE ON, IT IS NOT THE FUSE, I GUARANTEE IT.
I suspect that either your parking light switch has failed, or your brake lights are stuck on due to a defective brake light switch.

Had almost similar problem with one tail light. Get out of the carf while lights are on. Bang gently on the defective light and it may come on. Mine did. Probably loose connection.

may have a defective headlight switch or a bad relay for rear lights..

It sounds like maybe the starter solenoid is defective, they are prone to this type of problem and your description exactly fits. In order to repair this you must remove the starter from the car and either replace it or repair it with a new solenoid.

Defective wiring to the bulb.

Kit,

Most likely you have a blown fuse. Check the Fuse panel first referring to the owners manual for location and Ampere Rating. I would assume that the same fuse supplies power to both the Dash Lights and Tail Lights. This is pretty much common for many vehicles. If you cannot find a blown fuse then you may well have a defective Head/Tail Light Switch. Additionally, check all Bulbs in the Tail Lights. It may also be a separated connector somewhere between the Switch and the Tail Lights. If you can't find the problem yourself I strongly suggest you contact an ASE Certified Technician in Electrical trouble shooting. Good Luck.

hi if it is only the one bulb not working/tail light and the front light on same side is working along with number plate and other tail lights may i suggest you replace/check the bulb on defective light as if fuse had blown ? the front light on same side would not be working if you put ignition on and press brake your brake light shoul work ? if so change the bulb as the bulb has two elements inside tail light and a higher wattage element for brake light

Tail lights or brake lights? If it is the brake lights the brake light switch is stuck shut. Replace it. If it is tail lights, then possibly the light switch is defective.

If you open the trunk and remove the rear trunk trim, at the tail light area, you will see the fasteners that hold the tail light in position. Remove the fasteners and the tail light will come out, you can replace the bulb that is defective.
Good luck.
Regards,