Here's a good one. I got a fairly good deal on a '93 240 with a sunroof and have owned if for two weeks now. I've been looking it over and it's in very good condition. Someone even added daytime running lights, or so I thought. After driving it a while the lights seem to be on whenever they feel like it. At first I thought some former owner had installed a photo cell to detect outside light for automatic headlights since they mostly seem to be on automatically at night.

I finally figured it out. The other day I pulled into the driveway during the day and the headlights (and all the other outside lights) were on. I could see them reflecting off the garage door. Before killing the ignition, I happened to turn the radio off. The headlights went off. I turned the radio on, the headlights went on.

With the radio off the headlight switch works normally. With the radio on, the headlights, tail lights, etc. light and the switch has no effect. It's an aftermarket Sanyo radio that a former owner installed of had installed. They did a nice job and even the power antenna works fine.

Obviously someone somehow wired the radio power to the wrong side of the headlight relay. My questions are:

1. Has anyone ever heard of a goofup like this?
2. Has anyone ever heard of someone doing this deliberately?
3. Is there a way to download or otherwise get a clearer electrical wiring diagram than the Berkley manual has?

Thanks, so it goes,
Mark

 

Remove the radio and find the Dimmer wire off the radio. Disconnect it and see if it works properly then.

You don't need it connected to the radio.