Cadillac Repair: 1991 seville, turn signals, emergency flashers

Question
how come my rear turn signals work fine until i turn on my headlights then my passenger side rear turn signal stops working. all others are fine

Answer
Hello,

Three thoughts come to mind. One could be a bad flasher. Yes, this could affect just one signal with the lights on. 2 could be a bad ground at the right rear bulb circuit and 3 could be a defective bulb.

The 1157 which is the most common number bulb used with other variations like the 2057 has two filiments. One for the tail lights and when the two filiments work together for much brighter light would be for your brake light, turn signals and emergency flashers.

I will give you a first hand example of what can change just by changing a bulb. I put a l.e.d. bulb in my rear lights on my truck. When I turn the signal on flashes very fast. If a trailer is hooked up with the wiring, flashes normal. One l.e.d. burned out on the right side and I replaced the bulb with a factory bulb. Now, the right side flashes normal and the left side very fast.

I could have corrected the flashing by replacing the flasher with a heavy duty flasher, but never bothered.

I only gave that example to illustrate the answer to your question.

My first thought to your problem though would to change the flasher which is located under the driver's side of the dash.

Good Luck!

Rob