Dead short

Topic: Dead short (Read 925 times) previous topic - next topic

Dead short

February 12, 2007, 07:06:44 PM

I have a dead short in my 1986 mercury cougar XR-7 2.3 pulled fuses and many relays and still there. The battery drains in about 3 days help please.

Dead short

Reply #1 – February 13, 2007, 12:00:12 AM

I would call that a slow drain.
What kind of tools do you have for trouble shooting electrical problems?

Dead short

Reply #2 – February 13, 2007, 12:12:29 AM

Quote from: softtouch;129200

I would call that a slow drain.
What kind of tools do you have for trouble shooting electrical problems?

geeetterrr done:D

Dead short

Reply #3 – February 13, 2007, 01:48:28 PM

what will i need i have a good amp meter. and a light.

Dead short

Reply #4 – February 13, 2007, 02:43:05 PM

Is your Amp meter part of a multi-meter that also has voltage and resistance testing functions?

I will assume, correct me if I am wrong, the car sits for three days without being driven. Sitting for three days with the fuses out, the battery drains.

Do you have a battery charger?

Is the car stock, electrically speaking?

With the battery charged disconnect the negative battery cable.
Hook your test light between the negative battery terminal and the battery cable. Does it light at all, even dimmly?

If the light lights, take all the wires off the starter solenoid terminal that the positive battery cable goes to.

If the light goes out, put the battery cable back on.
Light still out?
Touch the other wires one at time to the solenoid terminal to find which one lights the light.

Let us know what you find.

Dead short

Reply #5 – February 13, 2007, 02:54:28 PM

this one might be worth investing in a good multimeter for. i'd disconnect the negative and hook up the meter in amps inline with between the battery and the cable, make sure all accessories are off, measure your amp draw, and pull fuses one at a time until you find the circuit you're working with, then find what all is on that circuit, and then go from there. (i just re-read the post. well, get a good digital multimeter if ya ain't got one already. and, uh, if you pulled all the fuses already and it's still there, look at the schematics before the fuse block.)

Dead short

Reply #6 – February 13, 2007, 07:56:23 PM

ok guys will try it all. thanks so much for your input. very much appreciated.

Dead short

Reply #7 – February 13, 2007, 10:41:10 PM

One thing to make absolutely sure of when trying the ammeter method is that the dome light, hood light, glove box light, center console light, and trunk light must all be off.

Also, try unplugging the alternator. A bad diode inside the alt will cause it to act like a motor instead of a generator. Since the "motor" won't be powerful enough to turn the engine, it'll just sit there and draw current.

Dead short

Reply #8 – February 14, 2007, 08:47:59 AM

The test light is the safer option if it works for you.

If while using the ammeter, you ground out the positive battery voltage while messing with the wires, you can draw more current than the meter can handle.
You may damage the meter or blow its fuse if it has one.

Also there is a normal drain from the EEC keep-alive memory and the clock. I think this is less than 100 milliamps.

If these test indicate no drain, leave the battery disconnected for three days and see if the battery can hold a charge. If not it's new battery time.