Tip & How-To about Cars & Trucks

Troubleshoot your lights

Fixing lights can be difficult:

You have a tail or brake light that doesn't work, but you replaced the bulb and no change. You'll have to troubleshoot, so buy a simple volt/ohm meter.

Be sure the power is off and no power on any of the socket pins. Then clean the light socket and connection pins with a stiff brush or steel wool.

First, measure all the light socket pins for power. If you don't see any voltage, must be a fuse out or a broken wire or you aren't getting a good solid ground reference.
Turn power off and make sure the socket ground is really ground by using the ohmmeter between the socket ground and a known good ground. If the ohmmeter reading is 1 or 2 ohms the socket is probably good. If the ohmmeter measures higher, then the ground connection is bad or ground wire is broken. Try to trace the ground wire, run your own wire if you have to.
Once the the socket ground measures ok, then you have to determine which hot pin is bad.
There are two hot pins, one for each filament, tail and stop light.
Pick one and measure the voltage referenced to the, now good, socket ground.
You should have power now, so try a bulb in the socket.

This Tip still in work.

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1 Answer

1998 buick century high mount brake light doesn't work, bulbs have been replaced


there is a seprate ground that mounts to the frame of your car near the light usualy in trunk in between the rear speakers locate and make shure the conection is good.if that dos not solve it on the pasengers side rear light check bulbs for detereated ends if thay are then replace.this shuold solve you problem

Jan 19, 2013 | 1998 Buick Century

1 Answer

tail light is not lighting up in my 2000 ford expedition


brake and turn are the same filament in the bulb. Try a new bulb. if that doesn't work your going to chase a short/ground on that wire back to the switch. get a wiring diagram to help.

Aug 05, 2012 | 2000 Ford Expedition

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tail lights work but brake light doesn't. its the same bulb for tail and brake lights


Hi!
Maybe you have a problem with a brake switch or the bulbs. because the bulb has two heads in side one for the brakes and one for the tail lights. take the bulb out ad see if the both heads are ok and not broken, They are just tow springs. If they look ok,Then check the brake switch thats usually under brake pedal. Good luck

Any Thumbs Up would be appreciated.

Jul 02, 2011 | 2006 Hyundai Sonata

2 Answers

Tail lights wont work


sounds like ground problem- remove tail lights and look for wires going to body -remove screww clean grounding area and replace- both sides. You did not say whether the lights work when car is off? With car off and brake pedal pushed is there any brake lights ? If not procede with above.

Nov 07, 2008 | 2003 Chevrolet Cavalier

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