code.monkey

I've been battling a parasitic draw in my GT3 for a while (since I've owned it in fact). The car will kill a brand new battery (stone dead, no lights or anything) by sitting for just a week (key out of ignition and car locked). I finally decided to figure this out once and for all as I've had enough of buying new batteries!

First I flipped the driver's door latch with the door open to make the car think it's closed, then locked the car and waited a while for things to power down. Then I used my multimeter to check for a voltage drop across each of the fuses. All read zero, except for row A, fuse 1, which showed a 0.2 mV drop. This is a 30 amp fuse, for the driver's side power window. According to a chart I found online this voltage drop equates to roughly a 100 mA current across the fuse.

Then I tried a different test, this time connecting the multimeter in series with the battery. I flipped the trunk latch and locked the car. Once things had settled down, I was left with a draw alternating back and forth between 140 and 270 mA every few seconds, regular as clockwork. I then tried the same test with fuse A1 (driver's window) pulled, and got a draw of just 15 mA, which seems to me more like what it should be.

I'm now convinced something is up with the power window circuit. Both tests seem to corroborate one another.

Has anybody seen anything like this before? Perhaps it could be symptom of a failing window control unit, although that seems unlikely to me. The window works properly with no issues otherwise.

997_rich

delete

nwGTS

Good on you for getting this far. Slow draws are notoriously difficult to diagnos.
Do you have a wiring diagram for your car? With that, you could find all circuits funneling through that fuse (might be more than just the window motor).
If it is just the window motor, I'd have the motor and window switch pulled and check for any obvious damage (frayed wires, shorts, corrosion, etc). The motor/regulator failure is not an uncommon failure on 997s.
If you find something you'll at least know clearly that was the culprit. If you don't, i'd still replace them since they are relatively inexpensive. Then see if the voltage drop persists.

code.monkey

I don't have a wiring diagram so I'm not sure what else goes through that circuit, perhaps the power door mirror too? Anyway, I'm going to pull the door panel off and have a look.

I do know that the car was fitted with an anti-theft tracking device at some point in it's murky past, perhaps it was wired into the window circuit. If it's still active it could be the cause of the draw.

SR71BLACKBIRD

my 997.2 GT3 seems to have excessive draw also. I normally have it battery tendered when I am in town but this weekend unplugged for 2 nights when I when out of town and when I came back the Battery Voltage was down to 12.20 from the fully charged state of 12.75.
This car seem to draw a lot of juice when just sitting and locked up compared to my 95 993 which could sit for a couple weeks and still start.

Gptoyz

Nice find, I would have done exactly the same thing.

Since it had an aftermarket anti theft system I'm thinking a glass break sensor was possibly left behind. A lot of those aftermarket car alarm installers like to just tap power from the closest 12v they can find.

code.monkey

Today I pulled the door panel off to see if I could spot anything suspicious. Curiously it seemed like the door panel had been off before as the torx screws were a bit burred, and a couple of the clips were slightly broken.

Nothing out of the ordinary on the inside of the panel though:-



Nothing obviously wrong on the inside of the door either.



I even unscrewed the inner door skin to have a peek behind it, again I could see nothing wrong there. I tried unplugging the window regulator motor / control box and the door mirror, then retested for a current draw, and still saw the same high parasitic draw as before. So I don't think there's anything wrong in the door itself.

My next port of call was the fuse box, I removed the panel that surrounds it to inspect the wiring behind. This revealed something suspicious, as you can see below. It looks to me like some wires have been spliced into the wiring harness, the arrow on the left of the image points to them leading to a mystery box inside the door sill. Oddly, there's also bare wire that goes nowhere (see arrow on right).



I removed the door sill trim and pulled the carpet back a bit to get a better look. It's hard to see much though, it looks like I need to remove the inner sill panel to make any further progress. I ran out of time today, so I'll have to tackle this tomorrow.

Spyerx

the electronics on these are a little complicated due to the can bus arrangement
each door has a computer module that controls everything in that door
same goes for seats
front/rear of car/etc
those connect to the gateway module
so, if you want to check this for sure
unplug the door module.
see if draw goes away
If you have a durametric I believe (I'd need to check... ) you can code these modules out.

I don't have my gt3 at home right now, i have a full set durametric and i think there may be some tests in it for testing draw on some modules...

That extra wire
could have been from a track setup, old radar, old radio, theft system who knows

Anyway, best way to check these is with an amp meter across the fuse terminals. one at a time. Do after car has gone to sleep locked. may take a while, remove fuse one at a time and test across terminals. Maybe easier to do if you remove drivers seat and lay a blanket in there you'll be there a while.

BTW, the old cars, they do this sometimes, it's usually the relay that triggers the door open timer. Of course, these are old cars, no CAN bus :-)

code.monkey

I removed the insulation tape and this is what I found underneath. Circled on the left are the two wires to the theft tracker box (literally just twisted around, not even soldered). On the right are the leftovers from some other attempt to tap into the same circuit. Basically a bit of a pigs breakfast.



So, removed the crap...



And re-insulated the exposed wires...



Then did the current draw test again (car locked, gone to sleep), and bingo, current draw is down to 15 mA.



Problem solved! Except, how to get the tracker box out of the sill? I guess I could just leave it but I'd prefer to remove it if possible. Anyone got any tips as to how to remove this inner sill lining?

Spyerx

andrewgt3

nicely done.

code.monkey

Well I couldn't just leave it there. After some persuasion I finally managed to move the sill support out of the way enough to get the tracker thing out.



And here's the offending article. It's actually two boxes taped together, maybe one was a backup battery (probably long since dead). One thing's for sure, whoever installed it really loves insulation tape.

jonwb

Great find! What is it?