Battery Draining Overnight

Killa02 · Sep 1, 2008

Hello,
I've got an 03 Mach 1 but I figured I'd get more hits in the 4.6 section rather than the Mach 1 section. Anyway here's my question :

I pulled the positive cable off the battery and put a test light across it. It was glowing pretty brightly until I pulled fuse #39 - GEM (Generic Electronic Module). Anybody have any ideas other than swapping that module out? I've heard that a new one will need to be reprogrammed. I hate just swapping out parts without knowing for sure that it is the culprit, so any suggestions would be appreciated.

I've been pulling fuse #39 when I park my car overnight and so far it's stopped the draining issue. It does suck though because the keyless entry is disabled when I do this so I'm unlocking the car the old fashioned way, with the key, then popping the fuse back in before I start it up.

If there are any Ford Techs here to help me with my diagnosis or at least confirm it and steer me in the right direction, I would really appreciate it.
Thanks-Jim

Mustang5L5 · Sep 1, 2008

If you have a DMM that measures AMPs in DC current, you can wire it in series and see just how many amps that one circuit is pulling.

Killa02 · Sep 1, 2008

Mustang5L5,
I do have a meter and you're right, I'll check it out with that. I was using a test light because I had my wife watching it for any change as my melon was jammed under the dash pulling fuses. She comes in handy for things like this and pumping the brake pedal while I'm bleeding them

Anyway I've read that the GEM module is supposed to shut down after the car is off in approx. 45 min. If it does'nt it can drain the battery, so I'll have to check it all out again with a meter and see how I make out.
Thanks for your help-Jim

Rusty67 · Sep 2, 2008

The amp rack in the mach 460 sound system is notorious for keeping the GEM awake. My dad's Bullitt had this problem which the dealer supposedly fixed but it came back a few months ago. I havn't had time to crawl around in the trunk and look for a shorting wire but I would try pulling the fuses for the amp rack and see if the GEM goes to sleep.

Killa02 · Sep 2, 2008

Rusty,
I've got the mach 460 but I thought the Mach 1000 had the amps? Funny you should mention the stereo, because a few days before all this started the display in the 460 head unit stopped iluminating with the stereo on. The only way I can see the display is if I turn the headlights on? I wonder if this is tied into the GEM and keeping it awake? Thanks -Jim

Mossberg · Sep 2, 2008

Rusty67 said:
The amp rack in the mach 460 sound system is notorious for keeping the GEM awake. My dad's Bullitt had this problem which the dealer supposedly fixed but it came back a few months ago. I havn't had time to crawl around in the trunk and look for a shorting wire but I would try pulling the fuses for the amp rack and see if the GEM goes to sleep.

That would be my guess as to what the problem is. Either that, or you have an aftermarket alarm system which is causing this. I don't think that is your problem though since you probably would have already mentioned you have one installed.

Rusty67 · Sep 2, 2008

The Mach 460 and the 1000 both have an amp rack. The 1000 system basically makes the trunk unuseable. If you look in your trunk on the right and left side where the speaker are, you will see the factory Mach 460 amps.

Killa02 · Sep 3, 2008

Rusty67,
You are correct(but you already knew you were!). I didn't realize that each rear speaker has it's own amp. Had the car for 4 yrs but have'nt spent much time looking in that little trunk we have. Thanks for setting me straight.

I'm on this crazy schedule at work right know, since we're short handed, so I won't be able to check the car out fuse by fuse with my multi meter until the weekend. I did that this past weekend but my results were skewed since I did'nt know that the GEM module does'nt time out or go to sleep until 45 min.

My display to my 460 head unit stopped illuminating with the unit on a few days before all this started. It will illuminate if I turn the running or headlights on so maybe something is going on there? For *****s and giggles I pulled the fuse to the amp and the radio and see what happens. I'll be happy if I can just find what circuit is causing this.
The battery still drained with the GEM module fuse pulled so I don't think it's that. Looking at a wiring schematic that thing is a nightmare cause it's tied into so much.

I appreciate all you guy's help and I'll update this thread when the problem's resolved. I hate when I search on a forum for a car related problem and you find someone with the same thing but they never say how it was fixed.

The tech help you get on this site seems pretty good compared to most others. Thanks-Jim

Mustang5L5 · Sep 3, 2008

Hmm, sounds like something in the radio may be shorting out.

You could try disconnecting the head Unit one night and see if the battery still drains.

The meter in series is the way to really go as it will tell you how many amps the draw is.

Rusty67 · Sep 3, 2008

I think I would agree with that. The head unit or one of the circuits that run to/from it sound like they are causing the problem.

Whats the best way to wire in a temporary inline tester ? Starting and driving the car would be out of the question with a regular multimeter hooked up.

Mustang5L5 · Sep 3, 2008

Depends on how good of a meter you have. If you have a clamp meter that can read DC current, like this one

Clamp Meters And Extech 400A Clamp Meters - Davis Instruments Catalog

Then you can leave the batt hooked up and start the car and find your current pull.

Most simple radio shack type meters require you to hook the leads in series and pass current throught he meter itself, so starting the car with that is a NONO. Most have a 3A ot 5A max anyway before they pop the fuse.

Usually just unhook the neg and tough one lead to the terminal and the other lead to the cable and read the Amps

Rusty67 · Sep 3, 2008

How does Extech compair to Fluke ?

Mustang5L5 · Sep 3, 2008

I don't really know. I just google searched it and it was the first one that came up that style.

I was an electrican prior to my current career, and i wouldn't buy that one. I'd either get Fluke or Greenlee if you want a serious meter.

For simple automotive stuff, i use a cheap radio shack meter. I would never use it however on something i need to trust my life to though

Jbauer · Sep 4, 2008

PDI and FLUKE are the best meters IMO..but then again i don't have experience with a lot of meters.

IIRC, Fluke sets the standard.

Killa02 · Sep 5, 2008

Thanks alot to everyone that's been helping me out on this problem. I've had the fuse for the radio and the amp rack pulled for 3 days now with no problems. Before if the car sat for 12 hours the battery would'nt have enough power to turn the car over.

I'll be able to play with the car this weekend to see if I can narrow it down even more. I was thinking that I could put the fuse back in for the 460 head unit, with the radio off and the ignition off too, and see if there's any draw coming from the amp circuit. I'll also check the amp circuit with the head unit fuse pulled too. I'm trying to see what's causing what to power on when it's not supposed to.

Any suggestions on diagnosing this system would be greatly appreciated. Thanks again to all who have helped me so far. I've been doing 12 hr shifts overnight, so I have'nt had any time to play with the car all week . Just eliminating the problem so I'm not jump starting it so I can go home has been a huge help. -Jim

Rusty67 · Sep 5, 2008

What # fuses were you pulling ?

Killa02 · Sep 6, 2008

Rusty,
At first I was pulling one fuse at a time, but I messed up by not knowing about the GEM staying awake for 45 min.

Right now I have the 20 amp fuse marked Radio and the 30 amp fuse marked Amps pulled. Hopefully that is all that is on those two circuits. Have not had a problem since pulling those two, and before the battery would be nearly dead after 12 hours. Sorry I don't have the car with me tonight, I took my 71 Cutlass to work since it was such a nice night out. For that reason, I don't have the excact fuse location #s handy, but I'll post them tomorrow.

I know I'm not looking forward to the sore neck tommorow night after having my head jammed under the dash and in the trunk all day. Hopefully I'll have some definative answers, and this thread can be wrapped up or at least I'll know what needs to be fixed or replaced. I really appreciate your help-Jim

Killa02 · Sep 6, 2008

Rusty,
I pulled fuse #9 (amps) and fuse # 27 (radio).

Rained badly today so I didn't get much accomplished. I did put both fuses back in and with the radio off and the key out, checked for power at the rear amps. No power there. I know this doesn't eliminate the front amp so I just pulled the amp fuse back out and left the radio fuse in and see how it is in the morning.

Like I said, it was pouring out there so I didn't get much done. i did notice the deck shuffling through the cds as soon as the fuse was put back in but this may be normal?

I'm kind of hoping it's the deck since there's already a problem with the display anyway. In hindsight, that probably should have been my "tip off" in the the first place.
Thanks-Jim

Rusty67 · Sep 7, 2008

Its normal for the cds to cycle when the deck gets power for the first time.

Killa02 · Sep 8, 2008

Got it isolated down to the radio. Left the amp fuse pulled and the radio fuse in and the battery was nearly dead the next day. I'm going to pull the 460 head unit and see if anything is glaringly wrong but as far as diagnosing the unit itself but I'll admit that's above my skill level.

Only because the car is a Mach 1, I would prefer to replace the unit with the same one. I just like to keep the car looking stock, inside and out. I'm old school (and just old too,42) and the reason I bought this car is that it's the closest thing to a late 60's early 70's muscle car imho.

I might swap the unit out with an aftermarket one, but I'll pick up a stock mach460 in case I want it back stock down the road. That kind of opens a whole other "can of worms" since I don't think it's any easy swap if I want to keep the rest of the system.

Looks like it's Ebay or Craiglist time to track down a 460 head unit. Somebody ,on another site I think, had a link to a company that refurbishes factory radios. That's an option too.

Thanks for all your help-Jim

Battery Draining Overnight

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That is…until I whipped out my Bissell

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