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240 headlight relay

Well the second time I've seen this now so I thought I'd post a heads up in case any other 240 owners want to check for this. In the '86 and later cars there's a relay in the driver's footwell or behind the dash depending on the year which supplies power to the headlights when the ignition is on. Two cars I've worked on have experienced total headlight failure; the parking lights will work, but turn the headlights on and

*all* the exterior marker lights and dash lights go out. In both cases I found the plug on the relay had melted down and the connections oxidized. I was able to pop most of the wires out of the melted shell and put them in a "new" socket shell from the junkyard. One wire had a burned connector so I soldered a new piece on with a connector from the replacement socket. The relay had one burned contact blade so I replaced it as well, and gave the pins of the "new" one a shot of DeOxit for good measure. You can find the relay by turning the headlights off and on while searching for the source of the click under the dash.
Reply to
James Sweet
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4640&highlight$0+headlight+relay "There are actually two relays used for the headlights. A small relay was added to bypass the switch in 1986. This bypasses all the headlight current which used to go through the switch. There is an additional relay in the engine compartment where the headlights are switched between high beam and low beam. This relay has all the headlight current pass through it and is switched to either beam when you toggle the steering column lever. On most years the high/low beam switching relay is on the left inner fender. But if your car is like my 93 then it's the large relay on the right inner fender. Check that out for bad connections or possibly the relay itself crapping out. They do go bad since there is so much current going through them the contacts will fail." __________________

Reply to
Mr. V

Interesting timing on your post... A while back, I replaced the headlight switch on my '83 (no relay, afaik) because the original fell apart. Last week, turned on the headlights, they blinked then nothing. No running, no dash, nada. I could hear the faintest sizzle from under the dash occasionally as I switched them on and off. Checked fuses, etc., then reached behind the dash to check the plug on the switch. That was the source of the sizzle. The plug had worked loose and melted most of the plug sockets. Managed to push it on enough to make contact until I can get a new plug from the boneyard. Surprised the fuse didn't blow. More surprised it didn't burn to the ground.

Reply to
clay

In these cases, the lamps limit the current so the fuse doesn't blow, but a bad connection has a high resistance which dissipates power in the form of heat. The heat makes it oxidize and increases the resistance which increases the heat, so what happened is not surprising. Thankfully the plastic is flame retardant, so while it will sizzle and melt, it generally won't burst into flames.

On the older cars, it's a good idea to rewire the headlights with relays, they're brighter that way too.

Reply to
James Sweet

...but the duct tape I wrapped around it to hold it on, might.

For sure, going to do that.

Reply to
clay

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