Battery drain? Car won't start!

[START 'N CHARGE]

If the battery check outs (holds voltage by itself) ok, I'm going to charge the battery, and pull the wires going to the alt, then hook the battery up and see if it still draws

Good plan,and yes an alternator CAN cause parasitic drain while sitting if it has shorted diode(s).

 

[X3FBrian]

Alternator is 100% unplugged. Wideband and amps are back hooked up. Only thing different is Wideband power is tapped in with the radio instead of the instrument cluster. Car is reading 12.55 volts after I unplugged the alt and charged it up. Will report back in tomorrow.

 

[X3FBrian]

12.55 volts unhooked at 9pm last night.

12.15 volts as of 4pm

So from 12.5 to 12.1 in 19 hours. Not sure if the battery is settling down or where it's supposed to be at on these cars.

 

[black-plasma]

I had a similar problem just after buying my Cobra new in 2002. It was a little electrical box that controls the "timing out" on various components after you shut off the ignition and remove the key.

I've forgotten what it was called. But if I drove the car every five or six days it would start OK. But if I didn't drive it for seven the battery would be dead.

The box was replaced under warranty and I haven't had a problem since.

I hope someone else remembers what the box is called.

GEM module? That is what was draining mine, do yourself a favor OP and have a dealership find the draw for you.

 

[X3FBrian]

How much would the dealer charge you guess?

 

[black-plasma]

I don't remember off hand, but after trying for weeks to figure it out it was worth every penny. I wanna say it was less then $80 for them to run the electrical diagnostic.

 

[po-po 5.0]

the gem module is known for a couple different failures that result in a battery draw. However, they're generally a low amp draw that would result in the battery taking close to a week to discharge. Several people have found that removing one wire from the gem stops the draw, and doesn't affect anything on the car. That actually worked for me.

 

[ctrlraven]

How To Perform a Parasitic Draw Test - EricTheCarGuy - YouTube
[youtube_browser]KF1gijj03_0[/youtube_browser]


I had an issue several years ago with my 89 5.0, turned out to be the vanity mirror light wasn't turning off when the flap was closed.

 

[X3FBrian]

Someone recommended this:

Granatelli Motor Sports Sure Start Smart: Granatelli Motorsports

Anyone use it or hear anything about it?

 

[oldmodman]

GEM module? That is what was draining mine, do yourself a favor OP and have a dealership find the draw for you.

That's it. Thanks. I was drawing a complete blank. It was replaced and now the car can sit for a month and it fires up just fine.

 

[X3FBrian]

Just out of curiosity, how much did that cost you?

 

[black-plasma]

I'd look for someone parting out a wrecked mustang, the GEM module is the same for all models 99-04 I believe. I got one for free and just paid shipping. My local dealer wanted $250 or something crazy.

 

[X3FBrian]

New alternator, still draining! Anyone need a stock alternator? lol....It's really not that big of a deal to disconnect and reconnect the battery because I only drive the car a couple times a week but I shouldn't have to do that. Grrrr.....the search continues!

 

[Anabolic]

hmmmmm

 

[Anabolic]

New alternator fixed my problem. What did you do before this started happening

 

[ninty9cobra]

Make sure you don't have any aftermarket accessories hooked up to the Gem module fuse. This will not let the Gem module go into sleep mode and will drain battery in a couple of days. Lo Jack had hooked my Low Jack system to Gem module fuse and it would drain battery in 2-3 days. Had Lo Jack rewired to different power source and problem solved.

 

[86Fbody]

I am wondering if my alternator may be bad. I have a termy swapped Fox that has either a drain or the alternator isn't charging. It has a battery disconnect and stays off unless being driven. Is it possible that a parasitic draw could pull from the battery even with the switch off or is is more likely the alternator just isn't charging.

 

[X3FBrian]

Could be a bad battery? Try charging the battery up and completely disconnecting and measure the voltage over the course of a few days, should stay charged by itself.

 

[X3FBrian]

I pulled f1.6 underhood fuse and my reading went from 6.1 amps to .25 amp draw when car was asleep. Any insight?

 

[clbailey]

Subbing for exact same problem. Literally exact. Even got a red top and replaced the alternator. Still get a draw. Even replaced the red top with a new one still has a drain.