Date:         Sun, 6 May 2007 09:23:11 -0700
Reply-To:     GMac999 <gmac999@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         GMac999 <gmac999@YAHOO.COM>
Subject:      Re: Help identifying part (image provided)
Content-Type: text/plain; charset=iso-8859-1

One other thing I would like to add to Matt's description.  Also
check the
front of the vehicle for strange wires.  I've had two vehicles, one a
76
van, that had weird things happening with the lights.  The DPO's had
towed
them behind motorhomes and ran wires under the front to connect the
tow
lights.

Greg

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On
Behalf Of
Matt Roberds
Sent: Sunday, May 06, 2007 2:07 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Help identifying part (image provided)

> From:    neil <musomuso@GMAIL.COM>
> Date:    Sat, 5 May 2007 11:37:57 -0700
>
> http://web.mac.com/tubaneil/iWeb/Site%205/Mystery%20part.html

I know this part has already been identified and excised, but I
figured I'd
add a little...

Most small trailers in the US and Canada have one lamp on each side
that
serves as both the turn signal and brake lamp.  Historically, most US
cars
had a similar arrangement for their rear lamps, so hooking up trailer
lights
was pretty simple - the left trailer lamp hooked to the same wire as
the
left rear car lamp, and the right trailer lamp hooked to the same
wire as
the right rear car lamp.

Most European and Japanese cars, as well as more recent US cars, have
two
rear lamps on each side - one with a red lens for the brake lamp, and
one
with a yellow (usually) or red (sometimes) lens for the turn signal
lamp.
You've got two wires on each side of the car, but only one wire on
each side
of the trailer.  You can't just hook all three wire ends together,
because
that would make the lamps on the car operate incorrectly.  Using two
diodes
would sort of work - the car lamps would operate correctly, but the
trailer
lamps would only flash with the car turn signals until you stepped on
the
brakes - then the trailer lamps would come on solid no matter what
the turn
signals on the car were doing.

That box does the magic to make the trailer lamps behave correctly
when
connected to a car with separate rear turn and brake lamps.  They
come in
various flavors - some are a box with wires on both the "car" and
"trailer"
ends; some have wires on the "car" end and a built-in connector on
the
"trailer" end; some fancy ones have connectors to match the factory
wiring
harness on the "car" end and a built-in connector on the "trailer"
end so
they can be installed without any splicing at all.

The "trailer" end of the wiring is usually (not always!) four wires:
white (ground), brown (running lights), green (right turn/stop), and
yellow
(left turn/stop).  If you see a harness of white-brown-green- yellow
or
brown-green-yellow wires hanging out near the rear bumper of a car,
it's
quite often someone's attempt at a trailer wiring connection.
You can usually get 14 and 16 gauge four-wire "ribbon cable" (four
insulated
wires bonded together) at the FLAPS.

The "car" end of the wiring varies more, but on the converter boxes,
a
common configuration is five wires: white (ground), brown (running
lights),
green (right turn only), yellow (left turn only), red (stop).
Some converter boxes omit the white (ground) wires on both the "car"
and "trailer" sides, so there are only four wires on the "car" side
and
three on the "trailer" side.

Mini rant: The ground wire is NOT OPTIONAL!  No, it won't ground
through the
hitch ball - at least not after you hit the first bump!  Both the
trailer
and the car need ground wires.  Even a wire that runs from the
trailer half
of the connector to a sheet metal screw on the trailer frame, and a
wire
that runs from the car half of the connector to a sheet metal screw
into the
car body, is better than hoping it will ground through the hitch
ball.  The
Syncro Deluxe version is to make the ground wire one or two gauges
thicker
than the other wires, and to replace the sheet metal screw with a
bolt, flat
washer, ring terminal, toothed washer, (car or trailer metal), flat
washer,
and self-locking nut in that order.
Hitch-ball grounding and/or broken ground wires are the leading cause
of
flickering trailer lights.  End of mini rant.

In general, one of the few things that will drive you crazier than
DPO
stereo wiring is DPO trailer wiring.  If you have a car, truck, or
van
that's new to you and the outside lights are acting weird, run, don't
walk
to the back of the car and inspect carefully for signs of trailer
wiring.
This applies even if no sane person would attempt to tow a trailer
with that
kind of vehicle (i.e., Geo Metro or similar).  If there are strange
wires
dangling around that are connected to the rear lights, and you can't
convince yourself that they are stock, get rid of them.  This can
help your
sanity immensely.

Matt Roberds




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