Big Easy Sharkster

'94 GTS 5 spd

Amateur day with the german war machine

If I let the car sit a week, she won't start. Battery is 3.5 yrs old. Had it tested by Sears 3 mos ago and they said it was fine. If I disconnect the battery and let her sit a week, then reconnect, she'll start right up

Disconnected the pos cable from the battery and put an amp meter from Pos post to pos cable. It read 0.48 amp

Started pulling fuses, nothing until #25 (diagnostic connector, current-pulse tailgate, interior lights). Amp meter dropped from 0.48 to 0.18

Checked all interior lights (5 cabin, above CE panel, glove box, engine compartment), all OK, amp draw goes from 0.48 to 1.1 when light goes on. Door red lights only drop 0.01 amp when door closed.

Pulled #26 (tail gate release) no change

Does 0.48 amp draw sound like enough to run the battery down? Could the diagnotic connector be the problem? (where the heck is that?)

Thanks in advance

j.kenzie@sbcglobal.net

It sounds like a door edge warning light is staying on. I think you have to look inside the door through the window gasket with the window rolled down, to see if the lights go off when the door is closed. 1/2 amp will run down a battery which is not driven daily. 0.18 amps is fine though.
Good luck,
Dave

Bill Ball

Once you correct this, the draw should end up 30'ish mA. I agree with Dave that your door warning lights appear to be staying on based on only a 10mA drop.

jeff spahn

How do you correct the door edge warning light issues?

Big Easy Sharkster

hhhmmm, OK, I'll check out the door warning lights further. With the door open, if I manually push in the door switch, the lights go out (and therefore, the drop from 0.48 to 0.47 on the amp meter). But yr point is that it should be dropping more than 0.01

Bill, even with the #25 fuse pulled, I'm still showing 0.18 amps (180 mA) draw.... still too much, right? I've pulled almost all fuses with nothing else showing any change on the draw. I'll pull the balance of the fuses and see if any more drops.

Thanks for the help

Bill Ball

Well, I pull all the fuses. If it's still more than 30ma then I start pulling the plugs on the bottom of the CE panel (careful - there is a release tab that must be slid over to one side and each plug has a delicate catch on the top edge). If I find a plug that appears to have the responsible circuit, I fashion jumper wires for the connections between the plug and CE panel, connect them with the power off, put the power back on and pull the jumpers one at a time until I find the one involved. Then using the wire diagrams, figure out which device(s) it might be. It might be easy or it might get real complicated. Also, there are some unfused circuits that don't pass through the CE panel. You'll notice some smaller red wires on the battery positive post - those could be involved, so you should check what happens when you pull each of those.

If the door edge lights go out, then we were wrong. Although the small power drop doesn't seem right, I guess those bulbs are lower draw than I thought. So, you initially found 300ma on fuse 25 when you pulled the fuse, but I gather none of the lights were on to account for that. There are other things on that circuit, but it now becomes a sleuthing game with the wiring diagrams.

tmpusfugit

Aftermarket stereo equipment and aftermarket alarm systems are always suspect IME, for spurious current draws. One of my 928's had the monster amp connected directly to the + battery connector and depended on its internal remote switching to turn on and off, and it didn't turn completely off....and would drain the battery in a couple of days, max. (even with all fuses removed) Old cell phone installations such as used in the 80's and early '90's should also be suspect... an older Corvette we owned had 4 alarms installed together in a huge rats nest of wires,plus it had the cell phone and remote radar detector wiring, how it ever ran is beyond me, but complete removal of all solved several problems including battery drain while parked.....I am not trying to pick on aftermarket folks but I have yet to see my first sanitary installation of any of the above.....and years ago I did a couple of my own that were not "good" so I should not complain too loudly.....don't know that any of this is relevant to the OP's issue, but the aftermarket stuff is where I go for drain issues right after I verify everything stock is shutting off per design....

Rick Carter

I'm guessing a stuck relay, rear window defrost is common.

WallyP

You should have 20-30 mAmps (0.030 Amps) current drain. I went thru the same thing, and agree with Bill's suggestion.

The Usual Suspects include:
- Any aftermarket alarm system, stereo system, or remote locking system.
- The interior light circuit. It sounds as if your lights work as designed, but make certain. If the lights operate correctly with the door switches, they are probably OK.
- The cooling fan final stages. Easy to check - find the final stage amp on the panel in front of the radiator, pull one Phillips screw and unplug the amp. If the current draw drops, you need to replace a couple of FETs. (I have some FETs.)
- Stuck relay, with, as Rick says, the rear window defroster being a good possibility.
- Bad diodes in the alternator. If you (very cautiously!) disconnect the battery, disconnect the red cables on the positive terminal, then disconnect the main cable from the starter to the jump start terminal and make certain that it can't touch any metal, then check the current draw at the positive battery terminal, you can catch this one. With the extra wires on the battery positive terminal and the jump start cable disconnected, the only thing still hooked up should be the alternator.

There are almost certainly others that I forgot - good luck!

Bill Ball

Aside from the other more likely suspects already listed, I've had a seat motor draw - just needed to be worked a little bit.

I've had shorts in the wiring to the sunroof that made the window controller draw and act very wacky: https://rennlist.com/forums/928-foru...l-problem.html

Bunch of others I can't remember. I had a car that I could only get down to 50ma, but 30 is the target, as Wally said. The extra 20 was in a circuit going to the hatch and I never figured it out. Not enough to worry about.

My car is USUALLY 30ma, but occasionally something will stick and I'll find a substantial parasitc draw and dead battery.

Big Easy Sharkster

OK, good suggestions...

Bill, I should have better described the #25... I ensured all lights were off before conducting the 'fuse pull', therefore, the 0.48 drop to 0.18 was with all cabin lights off, except the door warning lights, and they only dropped 0.01 A (10 mA) when shut off.

Final Stage Output replace 2 months ago with rebuilt one from 928 Int'l. (Wally, you didn't have any) Battery problem was occuring before this but will check it out.

Only aftermarket I have is an old Escort Radar detector and a Porsche CDR-220 radio.

So, to summarize, I have 2 problems, one - is that with all cabin lights off, I'm still pulling 300 mA thru the #25 fuse and I shouldn't (480 mA drops to 180 mA when fuse is pulled). two - I still have about 150 mA of parasitic draw that needs to be found.

Many thanks the suggestions... going to try them now

F18Rep

I had a similar problem that turned out to be a glovebox light staying on - kind of embarrassing...;] Bruce

j.kenzie@sbcglobal.net

I have posted this before, so bear with me. You can measure current with an ammeter between the battery and + or -. You can also measure voltage drop across each fuse. The blade type fuses have two bare spots on top of them on either side of the amp number that you can see in the fuse panel. Put a digital voltmeter with a probe on each of these two spots. With no current, you will measure 0.00 volts. With current flow you will measure a value like 0.24 volts. It is much quicker to do this than to pull fuses and measuring current at the battery. I hope this helps, it really saves me time and if it is a fused circuit, you will find current flow by voltage drop across the corresponding fuse. Trust me.
Dave

SQLGuy

Good suggestion Dave.

Similarly, you can also pull fuses and measure current by using the Ammeter in place of the fuse. More work to pull the fuse, but easier apples to apples comparison of current draw by circuit. Also, I think the newer Buss and Littel fuses don't have the top side contacts....

In the OP's case, though, he's already narrowed things down to a particular circuit, it seems, but isn't sure what on that circuit is drawing the extra current.

j.kenzie@sbcglobal.net

You are correct. I can measure for current flow in 20 circuits in 60 seconds by my method. I'm just throwing it out there as a technique. If the OP really has it narrowed down to one circuit, why are we talking about defrost relays, etc.?
I'm nt sure he knows whre his problem is. I still suspect the door edge lights.
Good luck,
Dave