Battery draining overnight

[jremington59]

I recently purchased a used 97 exp with a 5.0. The last four mornings my battery has been almost dead. I purchased a new battery and fully charged it, and that didn't help.

I had a friend stop by today and do a couple tests.

He pulled the fuse that powers the memory and the clock and took a reading and got no voltage reading back to ground. We also tested the alternator and it was putting out over 13 volts.

With no power coming back to ground I haven't a clue where to look from there. The only thing I'm wondering is if the previous owner hooked something up directly and not through the fuse box, but I can't find anything.

Anyone with any other ideas?

 

[jremington59]

I just went back out and tested it again, and with the neg terminal off, I got a reading between the battery terminal and the negative terminal of 9 volts. I pulled fuses one at a time and none of them pulled brought the voltage down.

 

[tclark77]

This task can be quite hard without an amps probe due to light timers and the power saver relay, You can disconnect the negative and connect a test light between the battery and negative lead. the test light should be lit up, without unhooking the test light touch the ground cable to the battery negative for a minute or so to allow the timers to count down, then disconnect the cable from the battery ( all while not losing contact with the test light). If the test light is still lit brightly you have a draw. remove one fuse at a time while watching for the test light to go out (or substancially dim). Once you found the affected circuit you must trace out that circuit and find the culprit. Use common sense, glove box, map lights, alarms and aftermarket radios are common problems.

 

[jremington59]

Thx for the reply TClark.

I did what you suggested and there continued to be a draw of 9 volts. I even removed the fuses from under the hood. The truck is in very good shape with no rust, and I can't find where they have added anything directly from the positive terminal without going through the fuse box. I also looked at the positive cable and cant see where it could be worn and touching anything.

I'm stumped, lol.....

 

[tclark77]

not to sound like a ******, but you can't have a draw of 9 volts. load is measure in amperage therefore measuring with a voltmeter set on dc volts tells you absolutely nothing. A neat analogy to help understand these terms is a system of plumbing pipes. The voltage is equivalent to the water pressure, the current is equivalent to the flow rate, and the resistance is like the pipe size. You could have 100psi in the pipe but if it isn't flowing your going to continue to have 100psi. Your basically looking for a leak in the pipe.

 

[jremington59]

I must have done something wrong.

I disconnected the neg terminal and checked the voltage with a voltage tester by going between the neg terminal and the negative post. The voltage tester showed 9 volts.

I then went and bought a cheap multimeter and did the same thing to check MA and I got a reading of 0 doing it the same way. Was that the correct way to check out whether or not there is a draw somewhere?

 

[tclark77]

I then went and bought a cheap multimeter and did the same thing to check MA and I got a reading of 0 doing it the same way. Was that the correct way to check out whether or not there is a draw somewhere?[/QUOTE]

yes this is the correct way, you need to make sure your on the miliampere setting, you should bee seeing under 5 miliamp.

Seeing that your reading zero, ensure that your hooked up correctly and in the correct scale by turning on the headlamps with the meter hooked up. Off the top of my head I dont remember the current draw of a 9004 but lets assume it is 55watts. 55watts x 2 bulbs is 110 watts being supplied 12 volts will be just shy of 10 amperes of current. this is what you should see on your meter - 10000mA , be warned though that alot of meters are highly innacurate and fused at low amperage internally so take all testing in stride, like I said without an amps probe it can be very tedious.

btw, try tapping the ground wire on and of the negative battery post, listening for things (relays, etc.) turning on and off. concentrating again on things that run of battery supply and not off ignition, since the battery goes dead when the key is off.

 

[jremington59]

Thanks TClark for the advice. I had the meter on the wrong setting earlier and these are the correct readings. Sorry for being such a newbie with this wiring.

With all of the fuses in, and with the inside bulbs removed, I got a reading of 2.47 ma on the 20MA setting. I went through all of the fuses and I found a big drop after removing fuse 27. With that fuse removed the reading went down to 1.45 ma. Fuse 27 covers the underhood lamp, map lamp, glove box and dome lamps, visor lamps, acc delay, dimmer switch illumination and the 4 by 4 system.

I just don't know what any of these numbers mean.

 

[jremington59]

I went and borrowed a meter from a friend that's a much better meter.

I ran a test on another explorer I have and all I got for a draw was .21Amps which is well within the specs. I ran the same test on the one with the drain and I got a reading of 1.3 Amps, which is way to much. After removing fuse 27 the draw dropped to .37 Amps, which is still under acceptable limits.

The moral of the story is don't bother fooling around with a 15 dollar meter.

Would anyone have a wiring diagram that would show where the ground is for the dash light and accessories?

 

[jremington59]

I've made a little bit of headway with this.

I've narrowed the problem down to fuse 25, which is the GEM and speedometer fuse. With the fuse removed, I am now reading .04 amps, this after finding a short in the glove box light. With the fuse in, I am getting a reading of .40 amps.

I pulled the power out plug on the GEM and the amperage drop stayed at .40 amps. I then pulled the incoming plug to the GEM and the amps dropped to .04, the same as with the fuse removed.

I'm not sure if this means the GEM is bad, but it sounds possible so I am going to try and find a used one and see if that solves the problem.