melting headlight switch on 4000

[Jason Gray]

  I did a bit of research in the list archives and was able to find answers
to a couple of the questions I had asked about converting wiring to burn
both filiminents (wont work), and the need to re-wire the connection for
swapping 9004 to 9007 bulbs. Apparently without appropriate wiring change,
the stock 9004 plug burns both the high and low filiments in series for
ultra-dim lighting, no wonder there was no apparent focus to the light
pattern. I will modify the wiring and try again!
Jason K  Gray
Wasilla Alaska
'71 2-door 510 w/ L20B, DCOEx2
'73 2-door 510, L20B, garret T3, SUx1
510 website http://home.att.net/~jason510/

Those are not oil stains in the driveway, they are bluebird droppings.


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> For additional lighting with these lamps I'm going to rewire them
> w/relays to operate the low beams simultaineous with the high beams.
> Will post the results when I've finishd it.

If you're talking about dual-filament lamps (9004, 9007, H4) the results
will be blown bulbs in 5 minutes to 5 hours. BTDT. There's more heat
there than it's designed for.

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The MAIN difference between the 9004 and 9007 bulbs are

 9004: E-W filaments (filaments aligned perpendicular to vehicle travel)
 9007: N-S filaments (like the H3 setup. Points in direction of travel)

The 3 leads for the bulbs differ in that the High beam hot feed and ground
need to be swapped. AND 2 new grooves have to be machined into the plastic
of the 9007 bulb base. Great for a Dremel. I used a drill.(only power-tool
I had)
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1)  The lamp connectors and pin locations are identical, so the stock
    9004 connectors can be retained.
2)  Two wires must be switched: looking into the rear of the socket,
    the left lead and center lead must be switched.  On the '86 5ktq,
    yellow is originally ^the center, and brown is the left.  (**This
    is different from Ernest's initial post, which specified left and
    right, I think - the correction was supplied by Mike, and the
    clarification by me**)
3)  Where Al cut the wires used and bullet connectors to make the
    connections, I simply removed the rubber plug from the back of
    the connector to get at the wiring.  Pry out the 1/4" thick
    rubber plug used to weather-proof the headlight connector (don't
    tear it).  The connector contacts themselves can be withdrawn
    from the connector body by using a small pin (or an unbent
    paperclip) to slightly depress the tooth that holds them in from
    the front of the connector while pulling the wire out the back.
    Remove only the yellow and brown.  (On my 5ktq, the drivers side
    were striped, the right side were solid.)
    Pull the yellow and brown contacts out of the rubber.  Switch
    them and re-insert thru the rubber plug and slip them back into
    the connector body.  Make sure that the free end of the "tooth"
    is slightly above it's fixed end so that the contact is retained
    in the connector body (it will "snap" slightly when fully
    seated).  --this is the quickest and easiest conversion, and if
    you ever want to put 9004 lamps back in, you can simply reverse
    them to original condition.
    (Hey, do it the really REALLY easy way!!)
4)  Two grooves must be cut in the base of the 9007 lamps; a Moto-tool
    with a Dremel #194 tip is ideal, but I found that an 1/8"
    straight router bit in a power drill worked too.  Cut them at the
    same depth as the factory one; both location and groove depth are
    important.  Visual examination of the existing 9004 lamps shows
    where new grooves are needed.  (Actually, the top groove
    matched.)  For the geometrically challenged --like me, rub the
    three projections (actually just the bottom two) on the inside of
    the headlight housing with #2 pencil lead and press the bulb into
    place and wiggle it slightly.  This left clear marks on the 9007
    base (mine were light grey plastic) where the grooves need to be
    cut.  You can draw guide lines on the 9007 lamp, or freehand
    works, just go slow and keep them straight