High current draw! [Archive] - GrandAmGT.com Forum


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11-13-2011, 02:08 PM
My girlfriends Grand AM is draining the battery. After doing the normal troubleshooting for the dead batteries (alternator check, battery check, replace a good battery with a new one, I decided to measure the current draw of the battery with the car off. The car is is drawing about 2.4A.

With it being dark I decided to try to remove fuses until the current draw was lower. I had to remove the following fuses:

Trunk REL Radio Amp
Radio Batt

With all these out the current draw is now 0.1A. That still seems a little high. Does anyone know the normal current draw.

No for the real issue.It seems that the radio and the amp are always drawing current. From the radio wiring diagram, it looks like the radio and amp are always connected to the battery. I do not see a relay or a or signal to turn the radio on. What does turn the radio off when the car is off? Does anyone have any suggestions or idea on what could be my problem?

Thank everyone in advance.

11-13-2011, 06:17 PM
The radio and amp are connected to the rap module (retained accessory power), that enables you to have the radio on after the ignition is shut off, until the door is open. Yes there will be a constant power to the radio, this retains all the clock and radio presets. As for the amp I believe it is a switched ignition input as well as the stereo, I'd have to look at the diagram.

As for the current draw, 0.1a is high. It should only be a few milliamps, again I can't remember, I haven't worked at the dealer in a few years now. But, you battery rundown protection typically covers you for stuff like the dome lights, etc. It does not cut off power to the cigar lighter etc. You just have to continue pulling fuses one at a time till the draw disappears and then trace the problem circuit.

11-13-2011, 06:51 PM
Thank you for your input. My problem is that there are several fuses that need to be pulled to get down to the 0.1A current. I am not sure how to isolate. My best guess would be a control module? To me that would be the only way to get so many things drawing current with the car off.

From your description, the rap module could be a suspect. The radio itself could be a cause.

Does anyone know where to get the entire wiring diagram? The only thing that I have found has been the audio system.

11-14-2011, 08:36 AM
You either have to go to a dealer or buy a manual for the complete schematics.

11-14-2011, 08:38 AM
Your likely lookin at the bcm module which is drawing the current. I'd have to look but I believe there is a micro relay feeding power to the bcm. Check the underhood fuse block.

11-14-2011, 04:00 PM
Btw you should have no more than 50 milliamps parasitic draw

11-14-2011, 08:28 PM
2.5 AMPS?! Um... That's quite possibly the worst draw I've ever heard of.

How long did you let the car sit with the meter on it before taking that reading? Sometimes it takes ten to fifteen minutes for everything to go back to sleep.

If you did let the car sit a good long while with the meter on it and still got 2.5A I'd suggest you start by unplugging the ignition switch to remove the possibility that its keeping something awake.

11-14-2011, 08:42 PM
what amp do you have, and is it hooked up to a factory head?

here's why i ask; i got a kicker that had "speaker line awaken", basically hook power and ground, and it listened for current in the line in, and fired up when it got it.

worked just great, until the car sat for 1 day. dead battery, so i started tinkering, and realized anytime i had anything on, lock a door, unlock a door, trunk, whatever, the amp came on, and was apparently still hearing something, as about dark i see it's power light still on.

short end, i went and ran a remote on line. like i was planning on to begin with, but then saw a nice little built in shortcut. threw the switch over to use the remote line, no issues since.

btw, the car sits for days at a time now due to having my little truck, no issues.
check your amp.

11-14-2011, 08:43 PM
Wow, I did not know that. I was only letting it sit for a minute. Guess I have to take all the measurements all over again. Is there any clips or leads that make this easier. I am only using a hand held meter with leads that I was holding by hand.

On another note. I have spent a lot of the day looking for a manual. The only manual that is see are for 1999-2003. I am thinking that this is the correct manual but guys at advance and auto zone both said no. I am not sure what to trust online. I would rather own something rather that get access like some of the sites. I also found Pontiac Grand Am 1999-2005 Service Repair Manual on tradebit but they get bad reviews. I would appreciate being lead in the right direction.

11-14-2011, 08:49 PM
Everything is factory on this car. To be honest, with Malaclypse's input, I am back at the starting point. I could have had a bad battery. I am thinking of ways to to measure current after it sits for 15 minutes. I could just drive it with the new battery but if my girlfriend gets stranded, I will be in trouble. lol.

11-14-2011, 08:55 PM
lol good luck with it man!

11-15-2011, 07:11 AM
The car didn't change from 2003-2005 when the production ended, the guys are idiots.

As I mentioned before, you have to let the car sit for about 10 mins for the rap and battery rundown protection to kick in. To be safe wait 15. Also wind the window down and close the door key out of the ignition. Do not open the door when doing a parasitic draw test, not only will you blow the meter fuse, but you'll wake the car back up. Then take a reading and proceed with pulling fuses and relays. There is a possibility you could have a relay that's defected in the closed position and giving something battery power.

11-15-2011, 07:34 AM
Just a quick question.

The fuses I am removing need to doors open. I hope holding the door switches or taping them is sufficient?

11-15-2011, 10:49 AM
If you can ensure the switches won't activate the lights that will be fine.

11-15-2011, 06:06 PM
You can buy a set of alligator clips for your meter... just make sure to get ones big enough to clip on to the negative cable and to the battery bolt you put in the battery negative terminal.