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datatrain · Posted: Thu Nov 20, 2008 8:20 am Post subject: This is new old stuff

About a year ago I found my battery discharging every few days when the car was parked. Thaz the old stuff.

In an effort to locate the source of the problem, we checked the charging curcuit and replaced the alternator and regulator during the summer. Still old stuff.

The battery was new last year and tests excellent.

All the light switches have been checked for a sticky one and none found. Trunk light turned off , dome light off. No glove box light. Still old stuff.

Put an amp meter on the battery and then pulled the fuses one at a time and found nothing. It didn't stop the leakage.

It appeared the ignition switch maybe was faulty after searching the forum for hints. Seems it can cause a lot of odd problems.

NEW STUff... changed it yesterday.

Pulled the old IGn switch apart. No burn marks on the contacts.

Put an ampere meter in the battery curcuit with the key off and it measures approximately 900 ma of leakage

I know the clock will pulse about 5 ma normally and that should be the only draw

So where do I look now ?

Thnx

_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

Grenadiers · Posted: Thu Nov 20, 2008 9:15 am Post subject:

If a 'tip' is out there, I need to know as well. My 931 decided to run thru batteries late this fall, prior, no problem. dave
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

Slam · Posted: Thu Nov 20, 2008 10:00 am Post subject:

Cable to alternator or starter chafed and rubbing?
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'88 944 Auto - may or may not resurrect

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

The only way you`re ever gonna get on top of this is to start at the battery and measure draw on every individual circuit, thick starter cable, two 4mm2 red wires to #H, alt loom, etc. Then isolate each sub circuit on the offending line and chase to a resolution.

Personally would bet you I could locate the problem in < hour. Seriously, if you have wasted a year to no avail it will be far more cost effective to drop the car off at an auto electrician before work.

Smoothie · Posted: Thu Nov 20, 2008 12:44 pm Post subject:

How 'bout the ol' pull one fuse at a time and see if the amp draw changes..

Also, accessory mode is switched on by just inserting the key and without turning it, so check for an amp draw difference between key-in and key removed.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Min · Posted: Thu Nov 20, 2008 4:02 pm Post subject:

personally I used the 'isolate stuff' type of diagnosis when I had a weird draw. I disconnected all the interior stuff at the battery and just tested the starter/alternator circuit, there was no draw, I reconnected the interior stuff and there was a draw, turned out in my case that one of the relays was installed backwards so the solenoid was active all the time. Test the interior stuff and the rest separately, locate the draw, and then start isolating the circuit, start by pulling out all the fuses, then pull out all the relays, until the draw goes away, start putting them back in until it comes back. If you find that there is a draw with all the fuses and relays pulled, then it also narrows things down. Shouldn't take very long.

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

zedex · Joined: 28 Aug 2008 Posts: 26 Location: British Columbia

I had this problem with the VW. Turns out the radio memory wire, when disconnected, solved the drain. I would not have thought the radio memory would draw that much and was right. It fed the radio power even when the switch was off. The faceplate did not light up, though.

After disconnecting the radio entirely, the drained battery issue was over. Ironically, now my Nissna truck is doing the same. I am going to reslove that tomorrow. BTW, same radio installed in truck. Odd......
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You get more with a kind word and a gun than a kind word alone--Al Capone

datatrain · Posted: Fri Nov 21, 2008 5:44 am Post subject:

Okay guys, I pulled all the fuses from the board and all the relays and checked the draw every few items. It remained at 900ma. When everything was out it was still 900ma.

I looked up under the dash and behind the instruments is a single inline fuse holder. It has a 25A fuse. When pulled out the the draw stopped.

I'm unable to determine from the Haynes drawings where it goes or what it's for. It appears to attach to the back of the fuse panel with about an #16 red wire. The other side of the fuse has 2 what look like #18 red wires coming out of a harness with other wires. So it isn't an add on.

Is it the power line to the fuse panel ??
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

StienbargerR · Joined: 28 Oct 2005 Posts: 1362 Location: Richmond, IN

Have you tried starting the car with that disconnected? If it runs and starts, and you cant find anything wrong with the car, I'd just leave it disconnected.

Maybe it was from an old aftermarket accessory like RC said, which was removed later on. My car has a bunch of random wires from an old aftermarket AC unit, which I removed.

Ryan
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1978 924 NA
-250lb lowering springs, Euro Pistons

datatrain · Posted: Fri Nov 21, 2008 8:17 am Post subject:

Okay.. the extra 25A fuse is for the AC controls. Which in turn control the heater.

Wiggling the blower fan controls would turn the leak on and off. When the fuse is pulled all is as god intended. No leakage. I would have thought this would be turned on only when the key is on.

This is a factory basic car with no aftermarket stuff so that should be wired correctly.

SO... I can relax and take the winter to pull the centre console and find why.

Thanx to all for your suggestions.
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

datatrain · Posted: Fri Nov 21, 2008 10:15 am Post subject:

Just for the record for the next unfortunate with this problem. On page 267 of Haynes it's fuse S19. It's 25A cos it runs the 2nd fan, the AC clutch and the blower motor. Looking at the schematic I still can't see a possible path, but it's there somewhere.
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR