Electrical leaks.

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J J - 16 Nov 2006 05:02 GMT

Recently I noticed that the left side of the instrument panel was very
dim at night. (87 Towncar) I thought that bulbs needed replacing, but I
was wrong.

While replacing the electric window motor on drivers rear door I had
motor and cigarette lighter disconnected. Suddenly the dim dash lights
were very bright again. I left the cigarette lighter disconnected and
dash lights are fine now. I suspect there was a small short or
something draining power.

I replaced both batter cables. The negative black cable touches metal
on several places so i put one of those plastic flex tubes over it.
After doing so the drivers door electric window now moves much faster as
if it has more power. Could it be that the new battery cable could of
been leaking power on the places it touched metal?

How do I find other small shorts or places where current is being
leaked?

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Scott Dorsey - 16 Nov 2006 15:43 GMT

>Recently I noticed that the left side of the instrument panel was very
>dim at night. (87 Towncar) I thought that bulbs needed replacing, but I
[quoted text clipped - 5 lines]
>dash lights are fine now. I suspect there was a small short or
>something draining power.

This isn't all that unusual for people who smoke and get various gunk
inside the lighter socket. Usually pulling the lighter socket out and
cleaning it will fix all that.

>I replaced both batter cables. The negative black cable touches metal
>on several places so i put one of those plastic flex tubes over it.
>After doing so the drivers door electric window now moves much faster as
>if it has more power. Could it be that the new battery cable could of
>been leaking power on the places it touched metal?

No. The black cable is connected to the chassis anyway. The reason your
door works so much better probably has more to do with disconnecting the
cigarette lighter so that short is gone away. It might have a little to
do with the new and less-corroded cables.

>How do I find other small shorts or places where current is being
>leaked?

Pull the battery terminal and put an ammeter on it. Then poke around
and see where the current is going. If the car is pulling 2 amps when
everything is shut off, that's bad and there's something that isn't really
shut off. If it's pulling 20 mA, that's fine.
--scott

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"C'est un Nagra. C'est suisse, et tres, tres precis."

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Woody - 16 Nov 2006 15:48 GMT

If the cables were shorting through the insulation you would have had smoke,
not low voltage. The connections on the cables were probably corroded
causing the low voltage. Reseat plugs and clean all ground connections. Make
sure they are clean metal to metal contacts...

> Recently I noticed that the left side of the instrument panel was very
> dim at night. (87 Towncar) I thought that bulbs needed replacing, but I
[quoted text clipped - 14 lines]
> How do I find other small shorts or places where current is being
> leaked?

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tom@rockauto.com - 17 Nov 2006 15:55 GMT

Over the summer my '89 Ford 5.0L also had dim dash lights and the
battery would occasionally go dead over night. The problem would
disappear for a couple of weeks and then reappear. I hunted high and
low for something draining the battery. The problem turned out to be
the alternator. I always thought of alternators either working or
failing completely, but this one failed intermittently. It was both
occasionally not charging and draining the battery. If the dash lights
go dim again, run and put a volt meter on the battery. If the voltage
is not around 13 volts then you could have a failing alternator too.

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