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Early 12v
BMW 2002 - High and Low Beam Relay Wiring
Directions
Article by Bill Williams
As 2002 owners,
upgrade lighting systems that include additions of driving lights
and auxiliary gauge panels, upgrade of sealed beam headlights to
H4s, and dash lights to PIAA 5w super whites, the stock relay and
switch configuration also needs upgraded.
There are options
in upgrading the relay and switch system. One option is to purchase
an upgraded harness (#30815 - For H-4 halogen lights, #30816 - For
H-4 halogen lights w/HB5 bulbs) from a supplier like Painless Wiring
(http://www.painlessperformance.com/catalogframe.htm). The other
option is to purchase components and build the harnesses. The home
built system costs about half of the packaged unit but requires
a couple of hours of fabrication time plus some basic knowledge
of soldering and insulating connections.
For clarification,
the early model 2002s low beam circuit does not have a relay but
it is fused in the stock fuse block on number 3 and 4. The high
beam circuit does not have a relay or a fuse.
This procedure
includes instructions to add two relays to the early model 12v 2002s
for high and low beams.
Listed below
are the needed parts. The part numbers listed are Susquehanna Motorsports
(610.944.3233 or www.susquehanna.com/susq) part numbers. Note: Susquehannas
web site has a good tips section on wiring schematics, which I took
much of my information from, and the site has a section on wire
selection. Dave at Susquehanna is a wealth of knowledge and very
willing to help.)
Parts list:
From Susquehanna
Motorsports
2 - relays #87483
($10.16 each)
2 - relay base
kits #87123B (includes the crimp connectors #87272) ($2.56 each)
2 - H4 adapters
#66490 ($7.85 each)
From Radio Shack
or other supplier
1 role - friction
tape
7 colors of
14 gauge primary wire (fewer colors may be used, careful tagging
of the wire is crucial. You may notice in the schematic and photo,
I only used five, wish I had used seven)
Solder
Shrink wrap
tubing
Zip ties
Dielectric grease
(Permantex 67VR)
Connections
to 12v power and to ground. (The type connections depend on owner's
preference and particular configuration.
Tools needed:
Soldering iron
(I prefer the new butane units available at Sears or Radio Shack.
Crimpers - this
a specific tool to crimp the connectors used on the relay base ports.
Radio Shack #64-410
Wire cutters
and strippers
Needle nose
pliers
Jewelers screw
driver or small pic.
Helping Hands
Wiring Vise from Radio Shack helps to hold the wires while soldering,
convince your wife, or bribe your kid to help.
Assembly instructions
Determine mounting
location for relays. This location will determine the lengths of
wire needed.
Cut the three
wires on the H4 connectors halfway between the male and female ends.
Now you will have four connectors, two female connectors and two
male connectors. You will not use one of the male connectors in
this procedure.

Assemble
the harness for the right headlight assembly:
(I chose to
ground the headlight assemblies on the drivers side inner
fender well. They can be grounded at other places. The ground point
chosen determines the length of ground wire.)
Solder lengths
of wire to the three leads coming from the female H4 connector.
The leads from the connector are yellow, white, and brown. The black
wire (on the left side of the connector) is the ground. The yellow
wire on the top of the connector is the low beam. The white wire
on the right side is the high beam.

Insulate the
solder connections with shrink-wrap tubing.
Wrap the harness
with friction tape.

Assemble
the left headlight:
This procedure
is exactly like the right harness, but the wires are shorter. Hold
off on wrapping the harness. You may want to include the next step
in the harness too.
Assembly
of the harness that will switch the relay:
This next step
is assembling the two wires that "switch" the relay on
and off.
On one of the
male H4 connectors, remove the ground connector from the plastic
base. This is done by inserting a small jewelers screwdriver
or pick in the top of the base and bend back the small barb that
holds the connector in the base and pull out the connector. This
is easy as long as you insert the screwdriver in the correct place.
Now you have
a connector with two brass connectors not three. Solder lengths
of wire to the yellow and white lengths of wire that were on the
H4 connector. Remember the wire you solder to the yellow wire, it
will terminate on the low beam relay point 86 and the wire you connect
to the white wire will terminate on the high beam relay point 86.
Insulate the
solder joints with shrink-wrap tubing.
Now you can
wrap this harness with the left headlight harness in friction tape.
Connections
to the relays:
Ensure you know
where you will install your relays in your car so you will have
sufficient lengths of wire in this step.
Cut the wires
the proper length to terminate into the relays and to reach whatever
ground point you will use.
Note on grounding.
As 02 owners know, grounding is important and we often have to remove
things as we work. I chose to terminate my wiring to the one of
the screw holes that holds the stock tii air-box on, but you will
need to determine your grounding point. I also used separate ground
wires for the four grounds you need, one for each headlight assembly
and one for each relay. I terminated these on the body with short
pieces of wire, ring connectors, and spade tips. Then I used insulated
spade tips and short pieces of wire to terminate to the relays and
placed insulated spade tips on the ground wires coming from the
headlight assemblies. You may not want to go through all of this
for the ground, your choice, just get good grounds.
Now, it is time
to connect this nest of wires to the relay bases. Take your time
and get rid of any distractions. As a review, connections to these
relays are:
30 from
battery power
86 from
switched power
85 to
ground
87 to
headlight assembly
87 to
your other headlight assembly
Crimp the spade
tip connections on the wires, you should have 10 wires to connect
to the two relay bases.
Mark one relay
base, high beam and the other low beam.
You are making
the connections into the relay bases by snapping the connectors
into the bottom of the bases. Later the relay will push into the
top of the base. Before you snap any of the connectors into the
base, set the relay into the base and somehow, make note of which
hole in the base corresponds the number on the relay, take your
time and get a good system going. This is important.
Disconnect the
battery.
Connect the
three wires from the right headlight assembly:
connect the
wire from the low beam to the low beam relay base, point 87,
connect the high beam wire to the high beam relay base point 87,
and
connect the ground wire.
Plug the H4 connector into the headlight.
Connect the
three wires from the left headlight assembly;
connect the
wire from the low beam to the low beam relay base, point 87,
connect the high beam wire to the high beam relay base point 87.
and
connect the ground wire.
Plug the H4 connector into the headlight.
Connect the
two wires from the switched connector:
connect the
wire from the low beam to the low beam relay base, point 86,
connect the high beam wire to the high beam relay base point 86.
Plug the new male plug into the female plug previously connecting
the drivers side headlight. You may use dielectric grease
on the metal connections. Tape the connection to ensure it stays
together.
Connect the
ground wires, from point 85 on both relay bases, to a ground point.
Connect battery
power to point 30 on both relay bases.
Installing
the relay bases and relays:
These bases
"gang" together so only one screw is needed to secure
the relays to the car. If you reference the picture of my installation,
the third relay is to my driving lights, it wires in the same manner
as the headlights.
Install the
relay bases to the car with a sheet metal screw.
Smear dielectric
grease on the male relay plugs and gently, but firmly, press the
relays into the relay bases. Turn on the battery, if you are unsure
of your work, unplug the lights and use a DVM to verify all the
connections.
Then check the
lights and hope for no smoke! If smoke comes out, you cannot put
it back in.

Please
verify all of these directions and connections; I am neither an
electrician nor a technical writer.
Bill Williams

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