Electrical Short for Interior Lights in 99 Accord

Hi all -

I have a '99 Accord LX 4-door that appears to have a short in the interior
lighting. It appears the only things on this circuit are the map lights in
the front headliner, the overhead light, the lights in the bottom corners of
the doors, and the door switches. The cigarette lighter (unused) is on a
different circuit.

The circuit runs on a 7.5 amp fuse - if I replace the fuse even with the car
turned off I get an *immediate* spark and a blown fuse. I tried with a
20amp fuse as well, just to see if the circuit was overloaded for some
reason, and I get the same result - immediate spark and a blown fuse.
Obviously a short.

The question is - does anyone have any ideas where the problem may lie, or
perhaps some steps to begin troubleshooting the problem?

Thanks for any help you can provide!

- Mike

 

Hi Mike,

|| I have a '99 Accord LX 4-door that appears to have a short in the
|| interior lighting. It appears the only things on this circuit are
|| the map lights in the front headliner, the overhead light, the
|| lights in the bottom corners of the doors, and the door switches.
|| The cigarette lighter (unused) is on a different circuit.
||
|| The circuit runs on a 7.5 amp fuse - if I replace the fuse even with
|| the car turned off I get an *immediate* spark and a blown fuse. I
|| tried with a 20amp fuse as well, just to see if the circuit was
|| overloaded for some reason, and I get the same result - immediate
|| spark and a blown fuse. Obviously a short.

Very obvious, yes If you put in a fuse and it blows with the car turned
off, something is Not Good (tm).

|| The question is - does anyone have any ideas where the problem may
|| lie, or perhaps some steps to begin troubleshooting the problem?

First step would be to have a schematic of the wiring so you don't miss any
parts. Do you have a manual that shows the wiring?

Next, replace the fuse by a lamp. (Yes, it won't blow, and it will light up
as long as the short persists, while reducing the current to a low level).
Use just about any 12V lamp (small 1 or 2W will do more than adequately)
attached to two leads that fit into the fuse; you could probably hack one of
your broken fuses to act as a socket for a little lamp.

Once you have the lamp in place, it will stay lit as long as the short
persists. Then go hunting for the short by disconnecting the various parts
that are hooked up to that circuit and watching for the lamp to go out...
that should get you there, eventually.

HTH,
TomB

||
|| Thanks for any help you can provide!
||
|| - Mike

 

Every so often light bulbs will short out when they burn out. I would do
as "tomb" suggested and connect a light bulb instead of the fuse, and
then start removing each of the light bulbs on that circuit to see if
any of them are creating the short.

 

Electrical diagrams are both in the Shop manual and in
Electrical Troubleshooting book. But you must have one or the
other. No reasonable way around that since appropriate
connectors and where they are located are important.

Tomb's idea of the light bulb is one excellent idea.
Another is to use the 3.5 digit multimeter in conductivity
mode (with fuse and all light bulbs removed). Meter leads
connect to shorted wire harness where fuse goes - and to body
ground. Meter beeps constant until you move reason for
short. The quick and temporary beep interruption tells you
problem located. An interruption that would not be observed
with a light bulb.

BTW, never again use a 20 amp fuse in that socket. The
spark when connecting 7.5 amp fuse made it more than evident;
it is a short. You may have burned additional wires -
complicated the problem