From: John De Armond
Subject: Re: Battery drain update (Dodge Xplorer)
Date: Tue, 15 Jul 2008 06:37:10 -0400
On Mon, 14 Jul 2008 20:38:59 -0500, "Darlington" <firstname.lastname@example.org>
>John, it's a Dodge class-b conversion van about 20 years old but in really
>good condition. It's the Xplorer. There's a drain on the front or truck
>battery of .2 amps. We narrowed it down to fuse #7 (see my post just above
>this one) but can't find what's causing the drain. If we pull fuse #7 the
>brake lights, dome light and glovebox light don't work but the drain stops.
>We can't pinpoint which one is the problem. We were unable to narrow it down
>any further. We've hit a brick wall. Or Dodge looks almost exactly like
200 ma is far too much to be tramp leakage. Something else is sucking juice.
Do you have a propane or CO detector? How about a car-type radio in the back
that needs memory backup? Does it have a fridge? My otherwise manually
controlled fridge had a little thermal switch that touched the flame and would
light a "fridge failure" light if the switch cooled off. The electronic board
behind the lamp drew about 100 ma all the time.
Here's the way I approach this type of problem. Find a lamp that draws about
100ma. A dome light or something. Fit it in place of the fuse. The light is
now in series with the load and will glow fairly brightly. Go around and
start disconnecting things and removing bulbs until something makes the light
go out. You've found your problem.
I had a hairy one on my rig similar to this on my rig. A fuse would blow in
the main lighting circuit just every so often. Replace the fuse, no problem.
I managed to get stopped one day with the short still in place. I fitted a
light bulb and then went around tugging on wiring harnesses. I found where a
sheet metal screw had contacted a wire and rubbed through the insulation. Only
when the body flexed just so would it make contact.
This light bulb trick has saved my cookies on a number of occasions. That was
just an example.
From: John De Armond
Subject: Re: Battery drain update (Dodge Xplorer)
Date: Wed, 16 Jul 2008 04:12:31 -0400
On Tue, 15 Jul 2008 23:47:22 -0500, "Darlington" <Datlington@thisfake.net>
>> Does it have a fridge? My otherwise manually controlled fridge had a
>> little thermal switch that touched the flame and would light a "fridge
>> failure" light if the switch cooled off. The electronic board behind
>> the lamp drew about 100 ma all the time.
>Where would the thermal switch be? All we found in the fridge was an on and
The switch itself was a little bent metal cylinder about the size of a pencil
lead that attached to the burner cover of the 'fridge and poked through a
little hole so that the end of it is in the flame. It had two wires coming
out - one went to ground right there at the fridge and the other ran through
the wiring system to the control panel. There was a little electronic board
behind the control panel. The purpose of the board was to take the signal
from the switch/sensor and illuminate a "refrigerator failure" warning light
in the event the flame went out.
>> Here's the way I approach this type of problem. Find a lamp that draws
>> about 100ma. A dome light or something. Fit it in place of the fuse.
>> The light is now in series with the load and will glow fairly brightly.
>> Go around and start disconnecting things and removing bulbs until
>> something makes the light go out. You've found your problem.
>OK... I'll see if they did something like this with fuse #7. I didn't know
>a lightbulb could act like a fuse.
The lamp isn't a fuse. It's an indicator that shows when current is flowing.
A meter could be used but then someone would have to watch it. With a light
bulb, when the glow goes away, the trouble has been found.
>The wiring can't be seen in this rig unless the inner paneling is removed.
>It runs behind the paneling and cabinets and probably under the flooring.
>There's no way we can get into a major job like removing the inner walls and
If all else fails then you may have to do what you have to in order to get a
look at the wiring. They may have hidden a gizmo in the wiring channels.
>If they haven't tried that these past 2 days I see if we can find a bulb to
>fit the fuse holder. The fuses are small and have a metal cap on each end.
This isn't a "see if we can find one" but a "go to the auto parts store and
get one" situation. That is, if you want to use this easy and definitive
troubleshooting technique. Also, you'll have to do what we suggest if we're
to continue helping.
You're going to have to do a few things to get to the bottom of this.
1) Ignore Boyd Brain. Nothing other than mental illness can explain some of
the stuff he comes up with. You're wasting your time paying attention to him
2) Pay attention to the rest of us, do what we suggest and report back.
3) Focus on the problem at hand and not alternative "solutions" such as
disconnect switches, pulling the fuse and whatnot. That just clouds the
water for us remote troubleshooter.
4) Quit treating the manual as the Bible. On a nearly 30 year old vehicle,
particularly one "customized" by a third party, the manual is, at best, a
suggestion as to where to start looking. Not only do conversion companies not
document what they do very well but in the intervening years, people may have
hacked the electrical system.
I agree with someone else in this thread who said that this 500ma load sounds
a lot like a small light. 6 watt pilot lights are extremely common. I've
found lights in the darndest places. Behind cabinets, in compartments and
other places that you'd never suspect. Sometimes the light is the result of
using a standard wiring harness in more than one application where one of the
applications has no use for it. Easier to leave it in place than snip it out
and tape up the wires. Other times the lights simply fall from where they're
supposed to be and end up hanging by their wires down behind something.
I suggest that you get the van to a totally dark place (drive it there if your
driveway can't be made totally dark) and carefully examine all inside AND
outside spaces for any faint glow. I'll just bet that there's a closet or
cabinet with a door-operated switch for an inside light that isn't adjusted
just right. My wardrobe has one that gets out of adjustment every so often
and leaves the lamp on.
500 ma would also be in the ballpark for a 12 volt relay or contactor coil.
Since I know nothing about your van, all I can do is make some suggestions.
Look at the van and try to figure out something that might need to be turned
on or off when the engine is running, the headlights are on or the vehicle is
in gear or in reverse. A relay to turn on the refrigerator's 12 volt heater
when the engine is running, for example. Another is the isolation relay that
many RVs have to connect the cranking and house batteries when the engine is
running so that both can charge.
One way to check for the relay or contactor idea is, while the RV is totally
quiet (drive it to a quiet place if necessary), stick the fuse in and out
while listening for the click of the relay. A stuck relay may not click but
Another indication of a relay coil is the character of the spark when you
remove the fuse. If there's almost no spark then the load is probably not
inductive. If you get a robust bright blue spark then there's an inductive
kick involved and that means a coil somewhere.
This amount of drain is also about right for a CO or propane detector. I know
that you said that you don't have one but I suggest looking again. I've seen
a propane detector mounted in the tank compartment. If yours has one like
that and has a removable propane tank then the detector could be behind the
tank, not visible until the tank is removed.
Does this rig have a tank level indicating system? If it does then it could
drain that much, even if you have to hold a switch to see the level
indication. If there is a switch, hold it and have the fuse pulled and see
Does the rig have an external radio or TV antenna? If so, is it amplified?
500ma is a bit much draw for a radio or TV amplifier but if something like a
dried-up capacitor has malfunctioned, it could easily be drawing that much
current. If an amplifier is at fault, dissipating 6 watts should make the
housing slightly warm. If there's a cable connection where you'd attach a TV
cable then the amplifier might be under that connector.
Finally, 500ma is about what the LED clocks in my rig draw. Even if you don't
see one, there may be one pushed back in or behind a cabinet or something.
Again, someone who may have modified the vehicle may have found it easier to
just push the clock back behind whatever it was that he was changing rather
than disconnect and insulate the wires.
If none of this work turns up the culprit then you're going to have to resort
to old fashioned wire tracing. Tugging the wire leaving the fuse will
sometimes work if they didn't bundle the wires too tightly. If you're really
lucky, they'll be color-coded.
If the wire goes off into dark and mysterious places then a wire tracing setup
is required. Those are sold at Big Box stores in the $35-50 range. You'll
want the one designated for telephone and network cables and not power wiring.
There are two pieces to this gadget, a transmitter that clamps between the
wire and ground and a receiver probe that lights or sounds off when the probe
tip gets near the wire. The transmitter injects a tone into the wire that the
probe picks up.
The better ones have two modes, voltage and current injection. The voltage
mode is for open circuits and the current mode is for wires that are shorted
or have loads attached. You'll want the later. The magnetic field produced
by the tone current flowing through the load is easier to detect than the
electrostatic field from the voltage mode.
Finally, take a look at every single hunk of wire or harness that you can see,
with an eye for splices, tape, heat shrink tubing, those 3M blue solderless
splices and other obvious signs of changes made post-manufacturing. IOW, look
for something that looks out of place.
If you take a systematic and organized approach to troubleshooting then this
load HAS to show up. This isn't sneak current or anything like that. Some
sort of load that was deliberately installed is drawing this current.