ThatOrangeTransAm

Im posting this for a friend with a 93 Formula.

Only one of the elements in the rear tailights work. If the lights are off, the blinkers blink at a normal rate. Also with the lights off, when the brake is pressed, only the high mount light works and ONE of the elements lights up, as if the lights were just ON.

With the lights on, and the blinker on, it blinks slow, really slow. Also, only one element works then, as if the lights were just being turned on and off. The high mount lights also lights up when the brake is pressed. With the lights on, only the side marker lights work, this being the small 194's at the outermost of the tailight.

So why is only one element working? Switch? Relay? Fuse? What Gives?

Thanks in advance,
Jimi

WhiteBird00

iTrader: (4)

I assume you have replaced the bulb that's not lighting - if not then do that first. The most common cause of turn signal problems is a burned out bulb.

If you are sure all of the bulbs are good then the next thing to look for is a bad ground. It sounds like the ground to the socket on the side that doesn't work might be bad. This would allow the lights to ground through the running light circuit when the running lights aren't on but would prevent current flow when the running lights are on. The third brake light is on an entirely separate circuit so it works independantly.

ThatOrangeTransAm

Thanks, that was my first assumption, that he had bulb out. I knew my TA done that whenever a bulb was out. We replaced all the bulbs, atleast all the 1157's. Its all 4 of the 1157's that arent working properly. Reverse lights and outermost "marker" lights work. If it wasnt for the 194's lighting up, he wouldnt have any lights on in the rear period.

Where is the ground located? I thought about this also, but I assumed since the 3rd brake light was working, the ground wasnt the problem. I didnt know it was its own entity.

Thanks again,
Jimi

WhiteBird00

iTrader: (4)

The ground is through the black wire at each socket. There should be a black (ground), brown (running lights) and one other wire in each socket. The third wire is dark green on the right side and yellow on the left side. This is the wire that runs the bright filament in the bulb for the brakes and turn signals. Remember, two-filament bulbs (like the 1157) still only light one filament at a time - one filament is just not as bright as the other.

Get a test light and connect the grounding clip to one of the bolts that hold the hatch lock for a good ground. Remove a bulb from its socket and use the probe of the test light to check the pins in the socket. Try every combination of lights on/off, turn signals and brakes to find out which combination works and which doesn't. If they all work then you know that the ground was the problem because you provided a good ground through the test light. If you still have the problem then you will have to trace further back in the system - for example, the brake switch above the pedal or the turn signal switch.

Let us know what you find and we can give you some other diagnostic ideas. I have the electrical diagram so I can get you wire colors and locations for testing if you need it.

ThatOrangeTransAm

Thanks man, Ill try that and post the outcome.

Jimi