Fixing battery draw

[LS1Hawk]

I've always had the problem of my batt losing its charge to start my car if it sits longer than a week or two. I finally determined the fuse/circuit that's been drawing on my batt, it's PWR ACCY. But I don't know anything about electrical. Does anyone know what the next step would be? Perhaps this is a dumb question, but should I take it somewhere to get looked at? I'm just not sure, because I don't know if that means ripping through all the electrical components on that circuit and pulling out wires and such. And does anyone else have this problem with 4th gens? Wondering if it might be a common issue...Thanks.

[89 Trans Am WS6]

Well if your sure that it is something on that circuit you could find out what runs on that circuit, both factory and things you may have added to it aftermarket (nitrous switches, line locks..watever). Then you could disconnect them one at a time..until you find what it is..

How did you determine the circuit that it was on?

Pulled fuses with a ammeter connected in series with a battery terminal?

Joe

[LS1Hawk]

I used a test light and pulled and replaced the fuses until the light went out or dimmed. According to the manual, the stuff from the factory on that circuit is parking lamp relay, hatch release relay, power mirror switch, radio, shock sensor, and instrument cluster. I'm not sure what aftermarket accessories may be tied into it though. I haven't added any aftermarket electrical. But the original owner of my car had put some extra stuff in like a remote starter, undetectable radar, some cell phone hook up, and a couple other things. I took all the cell phone stuff out myself, except its power cable... the other end of it runs up an under into the dash somehwere. I thought maybe that might be drawing some power still, but what it was powering I removed.

[89 Trans Am WS6]

Id chase that power line for the cell phone crap..


Might be laying on something metal..but not getting a perfect connection and not causing enough amperage draw to pop the fuse but just enough to be drawing on the battery...

It could also be somehow rubbed into another power line for something else..

Also could you explain how you used a test light going out/dimming to find the circuit? Not knocking anything just trying to figure out what you did..?

If i remember correctly the pwr accy circuit should only have juice when the key is in run/acc/ or its in RAP..(the retained accessory power that stays on till you open your door or 10 minutes after you shut the car off)

I would check and see if any of those accessories you mentioned are wired directly into the battery..and if they are..mabe you have to turn them off manually..like your radar thing or something..

Look into it and let me know..

Joe

[LS1Hawk]

Using the test light, I attached one end to the neg battery cable and held the other to the battery's neg terminal while my dad pulled the fuses. We pulled one fuse at a time and the light would still be bright, so we knew something was drawing. When we pulled the PWR ACCY fuse, the light went very dim, almost out completely. I think that circuit does have power on it constantly, because that controls the hatch release and shock sensor, all of which still operates when the car is off...but i could be wrong.

As for the cell phone power cable...it runs up under the driver's side of the dash. The last point where I can see it is by the diagonstics terminal, but it looks like it goes up somewhere behind it. I can't see where it goes because there's a lot blocking it, and it's pretty tight when I try to follow it with my hand.

[GP99GT]

the way they labeled it "PWR ACCY" is misleading. usually accessory means only when the key is on, but i think in this case it means actual accessories on the car, so yes, it could be a constant power wire. as for the actual problem, start tracing wires :p good luck

[V]

joe, you use the test light in series between the negative battery terminal and the ground wire. similar to using an ammeter but if all is normal the light will be very dim almost off, if theres a draw, the light will be lit up much brighter, when the problem circuits fuse is pulled, the light goes dim or out then. its a primitive and easy meathod to check for draws but it works great and not everyone has an ammeter.

[89 Trans Am WS6]

yeah i understand the method now, same setup as with a ameter..just more primative..lol

No biggie, i just like using the DVOM/ammeter for everything..more accurate and safer. Just like to use that example so people reading these thngs online dont think a test light is a end all and go probing around new cars..

With all the solid state stuff in todays cars a high impedence meter is just the safest way to go..

[LS1Hawk]

Well guys, after trying everything that was suggested and everything I can think of, the battery is still loosing juice. I've decided to take it in to the dealer to get looked at. I figure if they can't detect it, then I'll just have to deal with it. I made an appointment for the week after Christmas at Preakness Chevy. My dad brings his Vette there whenever it needs service, and they always do a good job. Only thing is they told me that it's mostly all labor when it comes to electrical, so it's going to be $99 an hour, @#&! I'm going to tell them to work on it for an hour and call me and let me know what they find, and then I'll make a decision.

[Pampered-Z]

I just went thru the same thing with my car and it turned outo be the battery. It was a 4 year batt, but it lasted less then a year. I fully charged it, left it on the bench then checked it a week later and it was down near 9 volts.

Can you possible swap your batt with the vett and see what happens?

[LS1Hawk]

My batt is a one-year-old Interstate Mega-Tron. About a week and a half ago, the battery was down to 11.5 volts, so it had a charge but wasn't enough to start the car. I recharged the battery, and since then have had the negative cable disconnected. I've been checking the charge on it pretty regularly since then and its been holding between 12-12.5. So it seems that the battery is alright. My dad's vette is a 78, so it has top mount terminals as opposed to the side mounts of LS1s.

[NJSPEEDER]

check your alternator. if it is dying, even a little, it can hang the circuit open adn slowly drain the battery

[Silent Z]

I would say if you knew someone with a Tech II GM scaner you could check to see if all of your modules are going to sleep. I had a 2001 Impala that would kill the battery every 2 days because the body control module would'nt go to sleep. Its just a thought.

[LS1Hawk]

I would say if you knew someone with a Tech II GM scaner you could check to see if all of your modules are going to sleep. I had a 2001 Impala that would kill the battery every 2 days because the body control module would'nt go to sleep. Its just a thought.

Yeah...unfortunatley I don't know anyone with one of those. And the last time I checked the alternator, it was fine. But I'm going have them check it as well.

[1QWIKBIRD]

This is probably stupid, but I had a similar problem on my car and it turned out to be the glovebox light....the glovebox door was out of adjustment and if you hit a bump or didnt' shut the door just right the light would come on and it was barley noticable, even at night....its a long shot, but give it a try...it might be worth $100...

Chris

[LS1Hawk]

Yeah, I tried the glove box. As much as I can see, the light is off when it's shut. But how were you able to tell the light was staying on? When the door is shut, it's pretty much sealed. I just checked the contact switch to make sure it was working and that was fine.

[1QWIKBIRD]

Yeah, I tried the glove box. As much as I can see, the light is off when it's shut. But how were you able to tell the light was staying on? When the door is shut, it's pretty much sealed. I just checked the contact switch to make sure it was working and that was fine.

The problem started as the weather got colder, and I attributed it to the car sitting for 3-4 days at a time, cause the battery would loose enough juice that the car wouldn't start. The one night I saw a dim light shining on the passenger seat, and though it was a reflection, but there was no light source outside the car. So I got lucky and gently pryed the door down a bit only to see light was on, but it would go off and on and off and on depending on how you closed/touched/bumped the glovebox door. So as a little test I removed the bulb for a few weeks and the problem dissappeared. Since them I have adjusted/shimmed the lock/door to make sure the switch is working properly and have had no problems since....Dumb luck really.

Chris

[Squirrel]

This is probably stupid, but I had a similar problem on my car and it turned out to be the glovebox light....the glovebox door was out of adjustment and if you hit a bump or didnt' shut the door just right the light would come on and it was barley noticable, even at night....its a long shot, but give it a try...it might be worth $100...

Chris
that was exactly my same problem, except mine was the console...i gotta put it down at the right angle or ill go to start a dead car a couple days later

[LS1Hawk]

Well I'm bringing my car in this morning. Just want to let you guys know I appreciate all your advice and it's helped me a lot. But I can't figure out what it is. Hopefully they'll be able to find out what's causing it.

[Tru2Chevy]

Hopefully (for your wallet's sake) it's something obvious that was just overlooked when you were testing things.

Make sure you post up to let us know what the shop finds.

- Justin

[LS1Hawk]

Hopefully (for your wallet's sake) it's something obvious that was just overlooked when you were testing things.

Make sure you post up to let us know what the shop finds.

- Justin

I'm hoping so, too. I have an extended warranty on the car. But there's aftermarket electronics wired into it. So if it's one of those, yeah I'm figuring a big bill. But at this point I just want it fixed, because I'm tired of having to jump the car, or disable the battery, etc.

[LS1Hawk]

Okay...They found a 150 milli-amp draw on the battery. They traced it to a wiring harness under the dash that was aftermarket and tied into the ignition. I told them the only things aftermarket that it could be are the kill switch, remote starter, radar system, or left over from the cell-phone hookup which I removed from the car when I got it. When they called me they had already put in 2.5 hours. They said when they unplugged the inline fuse from the harness the draw dropped down to 25 milli-amp. They said to find where the wiring went they would have to start taking apart the dash and trace more wires. The total for what they found was already at $250.00, and who knows how many more hours they would need to do more. So I told them if they pull the fuse and the car still starts with the kill switch (I don't really care about the remote start, I never use it), and everything is working the way it should, then to just leave the fuse out. They did and called me back and said the car started up fine and it didn't effect the kill switch or the remote start. I drove home and everything was working the way it did before. So the result is they were able to remove a 125 milli-amp draw off my car, yet I still can't say for sure what the culprit is (although I think it may be from the cell-phone thing). Whatever it is, it ain't getting power now. They said it's now drawing at a normal rate, so I'm going to monitor it some more and hopefully it won't die anymore.

[Tru2Chevy]

That's good. Maybe you can trace it yourself once the weather warms up, but for now you should be set.

- Justin

[LS1Hawk]

Yeah, if the fuse is out, all it is now a matter of extra wires being in the vehicle. I'm going to try to get a hold of the service manuals for 02. I'm not too keen on someone else ripping into my dash without me being there. So maybe I'll get in there myself. It's just strange to me how it was wired into the ignition, but when pulled didn't effect it. Even the guys at the shop didn't understand it.