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One of my brake lights is dimmer than the other.

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jrider

20+ Year Contributor
121
0
Mar 31, 2003
Detroit, Michigan
When I hit my brakes, my left brake light is much dimmer than the other. I pulled both of them out from their sockets and can easily see that the left rear light is not lighting up as bright. If I just swap them (switch the left and the right lights), the left is still dimmer. So it isn't just the bulb, it is that actually socket. Has anyone experienced this? Any thoughts would be great.
 
Don't know why just yet!!!
1. Tell me - how bright are the left and right rear PARKING lights?
2. Turn on the directional signals. How bright are each of them?
3. ... And the hazards?
 
Sure is!!!
DOES SOMEONE OUT THERE IN DSM-LAND HAVE A WIRING DIAGRAM?
I was thinking for you to check the voltage at that bulb [with a voltmeter] to make sure that is reads 12v to chassis ground. then check the voltage directly across the bulb wires. If that is LESS than 12v, then the ground side wire is 'floating' above zero volts, for whatever reason. It's a starting point!!!
I could tell you more if I had a print of the wiring!!!
 
Good thought. Here's my thought. With brake lights, they seem to have two filaments. Only one of them is lighting, thus it is dimmer. Doesn't the different pressure you put on the brake effect how bright the bulb lights. Could something be wrong there?
 
Yup, you're wrong. It's two different circuits, the brake light circuit controlled by a switch on the brake pedal. You have the bulb in backward. The knobs on the bayonet are stepped so that the bulb is supposed to go in only one way, but it can be forced in backward without all that much force. Get a new pair of bulbs and replace them on each side. Make sure they're put in with the correct orientation, it's obvious by looking at it.
 
~The bulb has two filaments... One is brighter [more wattage] than the other. The brighter one is for brake lights, and the dimmer one is for parking lights. That's why I asked about the brightness of the parking lights in post 2. I was trying to figure out if you had the bulb in 'backwards', that is - turned 180° in the socket, which would exchange the filaments.... But you said that parking lights are normal, RIGHT? -- so that's not the problem!
~No, lead foot or light foot - the brake switch doesn't know the difference. The bulb will light up equal brightness with any pressure.
 
Alright, if anyone can figure this out, please help! It is just too weird.

Okay, here's the most information I can give you. I turn on my parking lights, both left/right lights light evenly and normally. Now, if I apply the brakes with the parking lights on, the rear right light gets brighter (like it is suppose to). But here's the weird thing, the rear left light goes off completely. So, now I turn off my lights completely. I apply pressure to the brakes and the rear right light gets bright like it is suppose to, the rear left light lights as if all I have done is turned on the parking lights.

So here's the rundown:

Turn on parking lights = Both left and right parking lights light correctly.

Apply pressure to brakes with parking lights on = Right brake light gets brighter like it is suppose to. Left brake light goes off completely.

Apply pressure to brakes with parking lights off = Right brake light lights to its correct brightness. Left brake light lights as if only the parking lights were on.

If anyone can make sense of this, please help. There is definitely something wrong here, I just don't really know where to start.

P.S. I have used different (new) bulbs with the same effect. So we can definitely rule out bulbs being the factor.
 
I know you said that it's not the bulb, and I am probably also wrong but I'll share the experience anyways. in my last car I had the same problem with one light being brighter than the other, and I was burning through taillight bulbs like it was my job! they looked exactly the same but come to find out the bottom part of the bulb where it fit in had one prong instead of two like the other one. you probably checked already but just thought I would throw that in
 
Yeah, it can't be the bulb. Because if I take the bulb out of the working socket from one side and put it in the other and vise versa, it works on the working side without a problem. And the side that is acting up, doesn't work no matter what bulb I put in; even if the bulb was working fine on the other side.
 
im haveing some of the same problems on my right side tail light my middle bulb dont work when i push the brake when the parking lioghts are on turn off parking lights push the brake and it works. help please
 
You most likely have a poor ground on that housing. The common ground for the tail light circuit is located under the passenger fender, found by removing the splash shield. Multiple grounds plug into a harness and bolt to the frame.
 
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