Right Rear Brake Light Works, Right Rear Turn Signal Doesn't?

electrical-wiring
brakes
buick
lights
century

#1

I have a 2003 Buick Century. The rear lights are dual-filament bulbs (low filament for running lights, high filament for turn signal/brakes). I noticed that the turn signal wasn’t working on the right side, so I replaced the bulb. No good. In poking around, I figured out that the brake light was working, so the high filament was getting electricity through the brake circuit, but not through the turn signal circuit. What’s the problem? Bad relay?


#2

Well, just this week my grandaughter had brake lights but her right rear turn signal wasn’t working. I replaced the bulb, that solved the problem.


#3

I think your problem is in the multifunction switch at the bottom end of your turn signal lever but I would use an inexpensive test light to check it out. Pull the bulb and attatch the alligator clip of the test light to ground on the car body. With someone stepping on the brake with the key on, probe the contacts in the cavity until the test light lights up. Now have the other person release the brake and turn on the turn signal. If the test light doesn’t light up, the problem is up front.


#4

After looking at some data for your car it looks like Oldtimer 11’s advice is right on the money. The trouble has to be with the switch since the brake light shares the same wire coming from the switch. The wire color to the right rear light is dark green according to the data. You might be able to spray some cleaner into the switch and fix it that way or just replace the switch.


#5

I agree with oldtimer above. Test for voltage in the bulb socket before making any judgment about the switch. Test both contacts in the socket for +12v.


#6

The simple test would be to swap the right and left rear light bulbs. If the problem persists, the problem is the switch. The fact that the brake light works indicates that the problem is the switch. Do you have a front turn signal? Is it working?


#7

It’s the same filament for both turning and braking, isn’t it? The second filament is for the running lights.

Is the front turn signal working, or is it just the rear that’s out?

Either way, the problem’s in the wiring in the front. I’m sorry I can’t be more helpful than that. Unless this car has separate fuses for each side turn signals (I know some do).


#8

Thanks folks! I’ll take a look at that multifunction switch next. Maybe it just needs cleaned out.

For some additional information, someone had asked if it is both the front or back that isn’t working, and it is just the rear only that’s not working. Also, the flasher is running fast like it normally would when the bulb is out, so I would guess that something isn’t passing current through either at that multifunction switch, the flasher relay, or at a wiring harness somewhere.


#9

Say Cougar, you’ve got me thinking. Do you know somewhere online where I can see the wiring diagrams for this circuit? That might help me to track down where it is that the juice isn’t getting through.


#10

There is no other path to the light. Since the brake function to the light works it proves the path to the light is good. The trouble is with the switch contacts inside the switch for the turn signal function.

Autozone has some limited wiring info available online for a lot of cars, but not all. You should be able to get some information through your local library also. I suggest you purchase a factory service manual that covers the wiring at least. A manual is really a ‘must have’ in my book.


#11

have you resolved this issue? I had a very similar problem with my car. My first instinct was to replace the bulb. Replacing bulb did help but I was still having issues with quick flashing turn signal, etc. I posted my problem and someone kindly explained to me that with dual filament bulbs, there are nibs on the side of bulb that must correspond to the correct contact point. One nib is higher than the other. I had incorrectly replaced the bulb with the wrong filaments going to turn signals and breaks. So one filament was draining all the power. (you would think there is one way to replace bulb.)

I suggest taking out bulb (assuming that it’s good or new) and realigning the nibs. Basically, it took two tries for me. I put it in one direction…did not work…then turned(rotated) it to other side and it worked.


#12

Honestly, there is only one way to put it in, but since the bulbs and mounts are somewhat fragile, there’s only so much deterrent they can use. There’s no real substitute for close observation. Lots of people force them in the wrong way, don’t feel too bad.

Having said that, good catch. Didn’t think to mention it, as it seems so obvious to me.