92 Grand Marquis, circuit for fuse #4,5

[hieroglyphics]

Hey all! I love my car but its been givin me grief lately. Specifically, theres a short that pulls 0.23A of current when the car is off. All of my testing was done by measuring the voltage across a 15 ohm power resistor that is in series with the positive terminal of the battery. First, I began my troubleshooting by yanking each fuse one at a time at the power distribution fuse panel next to the battery. I found the culprit there which is labelled

LAMPS
FUEL PNL

and is a 40A fuse. This fuse fed a portion of the fuse panel inside the car. I then went on to check all the fuses in the inside panel where I found fuse #4 and/or #5 were the culprits. Here are my results:

All fuses in, doors closed, V = 3.2V
All fuses in, door open, V = 11.4V

Both fuses (4,5) removed V = 0.45V (doors open and closed)

Fuse #4 inserted:
door closed, V = 0.5V
door open, V = 11.3V

Fuse #4 removed, fuse #5 inserted:
door closed/open, V = 3.2V

Remember, all these voltages indicate the current flowing out of the battery, you just need to divide them by 15.


These findings have me believe that the circuit connected to fuse 4 is okay (maybe) and that the circuit on fuse 5 is shorted somewhere. Fuse #5 is a 10A red small-wafer and fuse #4 is a 15A blue small wafer. I tried to trace the wires but from what I saw they go up into the dash.

If anyone has the original manual for this car or is a genius and happens to know the circuits connected to these fuses, you'd make me one happy dude!
Thanks all!

[6502dude]

Not sure if this will help......

Had a similar parasitic power drain on my 89 Crown Victoria. It turned out to be relay which would remain stuck on when car was off (I think it was the fuel pump relay causing this).

This was a real PITA in the winter when I didn't have time and a warm spot to track down cause. At one point I was removing battery cable in morning when parking the car at work so I would be able to start it (without drained battery) after work.

There should be 3 relays on passenger side and you may be able to interchange them to see if problem goes away (and moves to another system). However, since you have VOM, I would see if there is 12v accross any of the coils with car in KO mode.

Relay replacement worked for me.