Hi all and Happy New Year, may 2010 bring many blessings.
Helping out a colleague with battery drain issues on his '94 GTS auto (I know this topic has been flogged to death so apolgies in advance). After cleaning up grounds and sorting out some dodgy audio wiring I'm getting 0.52 amp drain, ignition off, doors closed and the hatch plunger pushed down, and then a drop to about 15 milliamps with fuse 25 pulled out (the interior lighting/hatch release/diag conntr fuse). The interior lighting seems to work fine also the hatch release. So my question is: You GTS owners, is .5 amp drain usual or a bit excessive for this car? If excessive could the interior lamps controller be suffering some sort of internal short? I've suggested that he pull fuse 25 if not using the car for a few days, but thats hardly a fix! Also, with the fuse 25 out, I see that the tacho, fuel gauge, voltmeter and temp gauge are disabled.
Any thoughts would be helpful as always.
Thanks

 

First question always...

Do the interior lights work as designed? That is, do the interior lights go on when a door is opened, and go off shortly after the door is closed?

Does the glove box light work as designed?

Under-hood light?

 

I was reading in my Brian Long 928 book that at some point the EURO cars went to a system where the windows are always active... I don't remember what it said exactly but it caught my attention because my '92 GTS will drain the battery in a week or two where my '94 will go on for 6+ weeks before you can't start it. I just put my '92 on a battery tender if it is going to sit and I don't worry about the '94... My '88 and '84 can go for 2 months or more...hell, I think my '84 can go almost 6 months w/o a problem!

 

Thanks guys. The interior lamps, hood and glove box lamp all work as designed. Just reviewed my work this morning, the drain stays exactly .52amp with all doors shut, key out of ignition and hatch plunger pushed down. Pull that fuse 25 and drain drops to negligable. My S4 drains at about 20milliamp but I reckon the different models of 928 must have more going on electrically when the ignition is off. I have introduced the owner to the delights of a battery maintainer. Today's project is his fan fuses/holder...a burnt mess!

 

Hello and yes .52amp (1/2 amp) is excessive, 928 Specialist Web site shows:
Fuse 25 = "Diagnostic Connector, Current Pulse-Tailgate, Interior lights, and is a 7.5 amp fuse.
Is a 7.5 amp fuse installed in position 25?
Does the Rear Hatch remote opener work?
Do the door jam Lights work?
If I were doing this, I would start disconnecting things that this Fuse supplies power to.
Like unplug the Hatch motor, unplug and inspect each interior light, etc..

Please let us know what you find.

 

The interior light relay stays energized for about 20 minutes, so you have to be patient when trying to trace this problem. Close all the doors and start the car. Switch the interior lights to all positions. Every light should be on in one positon and off in two of the positions (center is off). If you have lights on in both postions, other than center, you most likely have a problem with the "second most common problem". See below.

The most common problem is that the driver's door switch doesn't ground when the door is opened. This keeps the interior light relay energized, because it thinks you are still sitting in the car. Turn on the interior lights so that they work when the door is opened. Make sure this switch works 100% of the time. (This might be hard to determine, if the "second most common problem" is the actual problem....see below.)

The second most common problem is that the switch in the bottom of the rear hatch release doesn't get pushed down far enough to break contact. The switch stays grounded and the relay stays energized, because it thinks the trunk is open. Almost the same solution. Turn on the interior lights so that they come on with the doors. If they don't shut off, disconnect the wire that runs to the switch at the bottom of the trunk latch.

 

Thanks for the ideas, the interior lights, door lights, hatch release etc all check out as good and a new 7.5amp fuse is fitted. This fuse also seems to supply the instruments so there may be some issues there.

 

A small development on the battery drain....the engine bay light comes on as soon as the hood is raised, shouldn't the headlight switch be at "parking lights" to enable this? That's certainly the case with my S4, is it different with the GTS?
Oh, someone please nip down to radio shack and buy a couple of 30A fuse holders for me!

 

I seem to remember a similar sounding problem on my GTS chassis which was traced to a loose wire in the rear hatch lighting circuit causing some current to ground but no enough to blow a fuse. I had given up no trying to find the cause but the local main agents found it in no time- rather impressively!

regard

Fred

 

The engine bay light in later cars (does on my 91, didn't on 88) does illuminate anytime bonnet (hood!) open, regardless of other lights.

For that reason I usually keep it disconnected, as otherwise I have to be careful it's off when I use a battery maintainer and I don't want light on all the time when I'm working in engine bay as those lights get hot and eventually melt.

 

Thought I was onto something with that hood light! Fred, you've prompted me to investigate wiring to the hatch, the light is actually broken (now he tells us!!) with two connections still on and the third taped back to the loom, it looks well insulated I might add, all the other lights work as designed.

 

I had no symptoms whatsover [flickering lights/lights that did not work] but my battery would run flat rather quickly [a few days would see it gone]- now no problems whatsoever [touch wood!].-

Regards

Fred

 

The battery on my GTS dies in about 3 weeks. I put a battery tender on it. I suck at fixing electrical problems.

 

My GTS had a weekly drain. I replaced the hatch receiver because the rubber was shot and for like $5 replaced both door pin swithes. Now, no battery problems at all. It hurt my head trying to figure it out--I didn't know about the 20 second delay on the interior lights... Doh!

 

Hi, I have a similar problem with excessive current absorption from my S4 MY88; if not used my battery drains off in a couple of weeks. What is the hatch receiver? where is it located?