Baffled by electrical glitch....

[midex717]

A year ago this past May the battery in my '97 Ford Expedition died at the 5 year point. I replaced the battery, and from the previous start attempts with the bad battery, the factory radio somehow shorted internally. Over the next month or so, the battery discharged, and the truck had to be jumped a few times. I figured the discharge was from the radio short, so I disconnected the radio, and didn't have any further problems. I replaced the radio with a unit from a salvage yard.

Also, at the first cold snap of last fall, I found out the new battery was bad, so I replaced that one as well, and had no further problems through the winter. The truck was outside all winter, and started for my daughter every time she need it to in -20* weather.

Now, here we are mid July. I get a phone call from my daughter that the radio has died again, and after a week or so, the truck will not start due to a dead battery. I charged the battery, and disconnected the radio. I am on the road for a long stretch, and have not been home to try starting the truck.

Any ideas out there as to what is causing this? Could it be a ground issue like a bad engine to firewall ground strap?

[jeffreyd]

prior to starting the truck, open hood and feel the alternator. see if it is warm to the touch. if so you have a leaking diode and need an alt. if not i would get a ammeter and volt meter, hook it up to the positive cable and see if there is a draw. if so, start eliminating things like the radio, or other appliances. watch the volt meter to see if when you pull a fuse the voltage goes to zero. the computer might be pulling a draw too. the old ford radios are notorious for going bad. you have a draw from something, and can keep replacing batteries but that wont solve the issue as you have noted. good luck.

[fishing tech]

Car phone charger or anything plugged into lighter or power points would also be a good place to start. If these are left plugged in and the alternator isn't working right and/or alot of short trips and sitting. the battery will never get fully charged.

[Jeremy airjer W]

I agree with checking for draws as a first step. It may be a fluke that unplugging the radio solved the problem.

What brand of battery is it? Please don't say its a werker or everstart!

[Scott K]

Have you noticed that it will happen after it rained, or a a day after that? These trucks have had problems with the windshield leaking and dripping water into the gem module and fuse box and causing electrical drains, and even the starter to kick in by it self and crank the engine until the battery goes dead. Pull back the carpet on the drivers floor and see if it is moist, or if you can see water spots up from that area. Also if you can, pull codes from the Gem module.

[Jeremy airjer W]

Didn't think of that one. The first time I ran into that I was baffled for about an hour and a half!!! The one I had would start and the windshield wipers would turn on all by itself. Very strange things can happen!

[midex717]

Thanks to all who have replied to this mystery, I really appreciate the insight!!!

I will try to take notice if the glitch occurs after a rain event. Is the Gem module located under the steering wheel where one would plug a code reader into? Another thing related to the radio is the coax end of the antenna was found to be rusty when I first pulled the radio, so there could be a relationship there with the windshield leaking. I'll try to check after the next rain event.

Thanks again guys!!!!

P.S. If there is anything in aviation that you would like answered I'd be more than happy to return the favor!!!