240 headlight relay

Discussion in 'Volvo 240' started by James Sweet, Jun 9, 2008.

  1. James Sweet

    James Sweet Guest

    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.
     
    James Sweet, Jun 9, 2008
    #1
  2. James Sweet

    Mr. V Guest

    from: http://forums.turbobricks.com/showthread.php?t=134640&highlight=240+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."
    __________________
     
    Mr. V, Jun 9, 2008
    #2
  3. James Sweet

    clay Guest

    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.
     
    clay, Jun 9, 2008
    #3
  4. James Sweet

    James Sweet Guest


    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.
     
    James Sweet, Jun 9, 2008
    #4
  5. James Sweet

    clay Guest

    ....but the duct tape I wrapped around it to hold it on, might.
    For sure, going to do that.
     
    clay, Jun 9, 2008
    #5
  6. James Sweet

    Dana Draper

    Joined:
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    I'm trying to replace my headlight relay in my 91 Volvo 240 is there any tricks I can try because I can't afford to get the part
     
    Dana Draper, Dec 25, 2016
    #6
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