colo993

A couple of months ago I started having a problem with my car not starting due to a dead battery. I replaced the battery and everything was fine for a week and then the same problem occurred again. I took the battery back to the store. The store offered to test the battery and charging system. No problems were found with the charging system so they replaced the battery. I am now on my third battery and still having issues with the car starting. If I change the battery overnight then everything is fine for a couple of days.

I found some good information on Rennlist for diagnosing battery drain with a multimeter. After pulling out almost every relay and fuse I found that relay R33 was causing a 0.68 mA drain. If I remove the relay then the drain is gone and the battery is fine. I replaced the relay with a new one and the car was fine for a couple of days. Now the power drain is back and the battery is dead. With the relay unplugged I can't use my sunroof, windows, or heater/defroster.

Has anyone experienced this problem before? I'm guessing here, but I suspect that there is something wrong with the sunroof. If I open it the drain on relay R33 seems to go away temporarily.

Thanks,

Paul

SPIKES

maybe the defroster...could it be on all the time?

shamrock

Ive heard a few tales of this relay draining the batt , though I haven't personally experienced it. A friend of mine narrowed it down to the motors for the window winders remaining 'live' after the car is turned off / doors closed.
Usually the windows will open/close , even if the key is out of the ignition and the door is open . However if the windows , or the sunroof can still be activated while you're sitting in the car with the doors closed , but key out of the ignition , then this is most likely your problem.

If this is the case , I'm afraid I don't know the fix , but I'll try to find out for you ... Let me know...

colo993

SPIKES - Thanks for the quick reply. I don't think it is the defroster because it usually makes a lot of noise when it is running and I don't hear it.

Shamrock - I will attempt to open the windows and sunroof with the ignition off. Thanks for the tip!

Paul

Robin 993DX

I have not heard of the same problem on anyone else's car, but year ago I had a short on the wiring from the front trunk mounted on the left hand side frotn trunk hinge which caused relays to engage even when the ignition key is off. Try to wiggle the wire in that area and see if you can hear any relays clicking in the fuse box. Long shot but worth a try.

What happened was the wiring insulation mounted on the hinge was getting brittle from opening and closing of the front trunk and caused a short with a constant postivie source.

colo993

Robin,

Thanks for the suggestion. I'll check it tonight.

Beautiful F-car in your Avatar!

Paul

Paul902

That's interesting...I just discovered that my battery was flat and frozen, after sitting for a few months. The trickle charger had become disconnected. I have the doors closed just so the latch catches, but there is still a gap (so that it takes pressure off the rubber door seals). Perhaps I had extra current drain because of that...

Robin 993DX

But I thought the windows and sunroof only remain powered if the door stay closed after you turn the key off, but as soon as it is opened the circuit is shut off.

grouchy

In my 944, the windows and sunroof could be operated with the key off as long as a door hadn't been opened. In my '95 993, the key turns off and everything turns off with it.

Robin 993DX

sounds like we just discovered another additional feature of a 96+ 993

shamrock

Yip , maybe it's different for N.Amcars (I doubt it) but the normal mode is for the electrickery to be shut off to the windows once the key is out and the doors are shut.

I had a chat with my pal who had that problem , and he said he cured it with a new relay , so I'm afraid that's not much help to you.