Re: IML: '68 Imperial headlight wiring

[dardal@xxxxxxxxxxxxxxx]

Quoting Kate Triplett <ad_ablurr@xxxxxxxxxxxxxxxxxxxxx>:

> As I am not having much luck in finding a new home for Lucille, This is one
> of the things I had on my "list" for her. In this dark-winter climate, having
> brighter halogen headlights  (or even better than that!) is just plain safer.
> I do realize the blessings of running that extra currrent through a relay,
> but somehow have missed where your instructions were posted. Could you please
> point me in the right direction? I would appreciate it!
> 
> Thanks and God Bless,
> kate


Kate.  In the original wiring, the switch gets power from the wiring harness and
then sends it to the head lights through a wire from the switch to the
headlights.  The idea of the relay is, first reduce the length that the current
would have to travel (from the battery through the wiring harness, through the
switch, back up front to the head lights, and then to ground) to a much shorter
length (battery, relay, lights, ground).  The second objective, critical to the
67-78 Imperials, is releave the main switch from the high current (these
switches are hard to come by, and difficult to replace).  

You first need to find the wire that sends power to the low beams.  When you do,
you cut it, close to the head lights, behind the grill (since the head lights
are connected in parallel, you have to do that for both head lights).  You will
know that you have cut the right wire by turning on the head light switch, and
making sure the lights indeed are off.  (make sure you cut the positive, and
not the ground wire.  You can confirm you have the right wire by removing the
little plug behind the bulb and inserting a test light or multi-meter terminal
in the plug, it should get "hot" when the switch is on, and the high beam/low
beam switch on the floor is at the low beam setting).  Then, you extend that
wire coming from inside the vehicle (by soldering another wire and insulating)
and connect that to the trigger electrode of the relay.  So now, the voltage
that comes from the switch acts as merely a signal to the relay, instead of
carrying the full current load.  The new relay is installed on the radiator
cross member via sheet metal screws.  The relay needs power.  I use the "hot"
wire of the starter relay on the left fender (that's a real beafy relay with
all these thick wires going into it).  Use a multi meter to identify the
"always hot" wire.  A relatively thick wire (held by the nut from that large
relay) can take the power from there to the power intput of the new [small]
relay.  The output of the relay is connected via another wire to the other end
of the cut wire of the low beams, the one on the side of the plug that is
inserted in the headlamp (the one you cut earlier).  Of course, you solder and
insulate.  You do the same for the light on the other side (i.e., the two low
beam head lights are still connected in parallel from the output of the new
relay).

Now, when you turn on the switch, the current though the switch is only what it
takes to activate the relay.  However, when you turn on high beams, the high
beams are still fed though the switch.  If you use high beams extensively, you
need to do the exact same thing for the high beams.  This time, you need to
install 4 wires, two per side.

Also, I have installed a fuse between the starter relay and the power input to
the new relay, just in case something shorts out.

D^2


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