Date: Mon, 9 May 2005 23:02:56 -0400
Reply-To: Kim Brennan <kimbrennan@MAC.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Kim Brennan <kimbrennan@MAC.COM>
Subject: =?WINDOWS-1252?Q?Re:_No_headlights_=96_high_beam_indicator_stays?=
=?WINDOWS-1252?Q?_on_=96_relay_upgrade_installed?=
In-Reply-To: <b7a8313c050509185314487281@mail.gmail.com>
Content-Type: text/plain; charset=US-ASCII; format=flowed
Okay. Time for some electrical 101: This discussion covers 86 and later
Vanagons. The wiring may be similar in earlier model years, but I make
no guarantees.
Most electrical devices work by having a positive current come in to
the device, do the work and the remaining current go to ground (voltage
differential).
In the case of lights, the work being performed is the transforming of
the electrical energy into light energy, via the glowing of (usually) a
wire.
This means you need positive voltage in addition to a ground. So the
first thing to check is...do you have positive power at the LIGHT BULB
when the ignition is on and the switch is turned on.
Get a Volt-Ohm-Meter. This is basic equipment for working on electrical
circuits. it is pointless to speculate until you have the basic tools.
This is the one you need. You can pick up a cheap one at RadioShack for
under $20. The main different in expense of VOM's is features and
quality of manufacture. For basic stuff on a car, an el-cheapo one will
work for now.
On the 86 and later Vanagons there are 3 wires going to the headlight,
with one of those going over to the hi-beam (which has a total of 2
wires). These wires will be Brown (ground), Yellow and White (Right
side will have a black stripe on the white and yellow wires). Yellow
goes to the headlight, White goes to the headlight and hi-beam.
Pull one side (drivers side or passenger side) of your headlight
carrier off the vehicle (held in place with 4 phillips screws).
Disconnect the wires to the headlight and hi-beam. Carefully set the
carrier with lights aside.
Turn the key switch on. Turn the headlights on. Attach one side of your
VOM (which should have 2 wires, one black, one red) to a frame ground
(normally you'll connect the black wire to ground.) Connect the other
so that you are contacting the metal conductor on the white and then
separately to the yellow wire. Did you get any voltage on either
(probably not.) If you did, temporarily connect the headlight and/or
hi-beam. Did it light? If it didn't. Next check the conductivity to
ground.
Switch your VOM from measuring Volts, to measure Ohms. Touch your two
probes together so you see what 0 ohms (connectivity) looks like. Some
meters have an audio beep setting, which can be nice to use. Now, with
the black probe connected to a conveinent frame ground, check the brown
wire for connectivity. If it doesn't beep or show near 0 ohms, then
your problem is with your grounds. If it showed connectivity, you have
a bad light bulb.
If you didn't have voltage at the headlight, you next need to figure
out why. The next place in the circuit is the fuse. You can pull the
fuse, and measure to be sure there is voltage at the fuse (one side
only). I have had corroded fuses that looked good, but didn't conduct
electricity.
If there is no voltage at the fuse, you need to look further. Since you
have installed relays, the next place is the relays. I'm not going to
dig out my circuit of the headlight relays. Suffice it to say, you
spliced into the white and yellow wires to install your relays. Check
the other side of relays to see if you have power. If you do, then the
problem is with your splices, or the relays or the relay connectors.
However, it is probable that you still don't have power so...
The next spot is the headlight dimmer switch. This is usually pretty
straight forward. A Red/Yellow and a White/Black wire come in to it,
and that same Yellow and White wire you've been looking at up to this
point come out of it. Check for voltage on the Red/Yellow wire and then
the White/Black wire. The Red/Yellow wire should always have power,
whether the headlight switch is on or off. The White/Black wire should
only have power when the headlight switch is on. If the Red/Yellow wire
doesn't have power, you have a problem with power from your battery and
I'm not going to pursue that in this message.
BTW, now that folks have gotten to this point, you can see why
sometimes your headlights don't work, but do when you pull back on the
hi-beam switch...it's because you are bridging from the always ON
circuit (that red/yellow wire) to the headlights, through the hi-beam
switch.
If the white/black wire doesn't have power when you turn the headlight
switch, on we next need to look at the headlight switch. Pull the
headlight switch from your dash. If it smells bad (burnt plastic), it
probably needs to be replaced, but you can check it for functionality
with the VOM. Before pursuing that, there should be a Red/Yellow wire
coming to the switch (should have positive voltage at all times. If it
doesn't you have problem with your main power coming from the battery.
It should also have power from a Black/Yellow wire, but only when your
ignition switch/keyswitch is in the ON position. If you have power on
the black/yellow wire when the keyswitch is on, but you don't have
power on the white/black wire when the headlight switch is on, your
headlight switch is bad. If you don't have power on the black/yellow
wire, then the next place of failure is the keyswitch. This is the X
circuit mentioned in the archives.
The black/yellow wires goes to the keyswitch. This is a switch attached
to the place you insert your ignition key (which is the keyed portion).
This should have a red wire coming in (with always on power) if the red
wire doesn't have power, you have a problem with the main power from
your battery.
The black/yellow wiring coming out of the keyswitch should have power
when the ignition key is in the ON position. If it doesn't and you have
power on the RED line, your keyswitch is bad.
If everything checked out here and you still don't have working
headlights go back to the beginning, because you've missed something.
