Questions and Answers

Ford Thunderbird High Beams Q. My son just bought an 1989 Ford Thunderbird. Upon inspection I noticed the high-beam headlights won't turn on. The "flash mode" works but they won't turn on. I don't know where to start the diagnosis. Also, the plastic headlight covers are worn and scratched. I would like to buff or polish them. Is it possible? Suggestions? Thanks for your help, Frank

A. I'm assuming the switch itself goes into and stays in position when you turn the HIGH beams on.

First I would check for power at the red/yellow wire going into the multi-function (turn signal) switch. If there is no power, then it gets complicated if you have Automatic Headlights. If that's the case, let the dealer handle it. We can go on if there is power there.

Now check for power at the light green/black wire coming out of the multi-function switch. If you have power there when the HIGH beams are on, then it's a bad Hi-Lo relay. If not, then you have a bad multi-function switch or a problem with the wiring.

This may sound stupid, but check the headlight bulbs them selves. I have seen them burn out together.