i went to go for a drive in my '89 S2 today, after it sat for 2 days. IT was completely dead, not even the interior light came on! After a jump it ran fine, i let it idle for 10 mins, as per owners manual instruction for installing new batt, to let the car reprogram itself, then took it out for a spirited drive, (that part was fun). What would cause the relatively new batt to die like that, i'm thinking only a short could drain it down that far, it rained really hard for a day and a half on the car but i didn't drive it! I checked, no lights or anything else was left on, only the clock and security system was on, as far as i know. any thoughts would be appreciated.

thx, john c.

 

How long was your cooling fan running after you parked the car? When cooling fan runs too long it could drain the battery. Just a thought.

 

Also if your earth cable on the battery is bad it wont earth properly if it's the original try changing it. Cooling fan usually stays on for a while about 10 mins.

 

thx, i don't think it's the fan, but it was a couple wet days so maybe that would've made a cable problem even worse

 

Alternator ?

 

Your predicament describes almost to a T what I dealt with today. '86 951, dark and stormy night, alarm going off incessantly during the wee hours (due to dying battery), waking neighborhood, disconnected battery to stop it. Next morning reconnected to find passenger side cooling fan running and driver footwell soaking wet. Installed new battery to find same fan runs incessantly, even after spirited road run. Searching forums for answers...

 

Look at Clark's Garage for the cooling fan trouble shooting but frequently it is the thermo fan switch in the radiator. That is easy to test and replace.

As far as battery going dead in a couple days, there are a lot of threads in the main 924/44/68 forum so do a search there. If it is rain/wet related this can happen if there is moisture and enough disolved in the water for it to act as a conductor - basically a soft short. It happens a lot on batteries that have dirty tops between the posts.

First you need to determine how much current you are drawing with the car off. 50 milliamps would be about normal. If there is a greater draw then you just start pulling fuses until you see power draw drop - now you know which circuit to start looking at for the draw. Common problems are the light bulb in the glove box, alarm systems and failed switches in the front door jamb that keep the windows powered up. And if you have an aftermarket sound system that would be high on the suspect list.

 

Check the glovebox light and the hatch light.

 

My 1989 944 did that a couple of years ago. It turned out to be a Thermo Sensor Switch that screws into the radiator ont he driver's side. It tells the colling fan when to turn on and when to turn off.

For A short while I had to pull the fan relay every time I parked the car for long periods of time. Finally I took the time to replace the Sensor Switch and fill up the collant and bleed the system. I have not had a problem since.

Jim

 

Can you please tell me just where the Thermo Sensor switch is. Does Clark's have reference and guidance to replacing it? Is it accessed from under the car?
Many thanks--

 

It is screwed into the upper left hand, rear side of the radiator end tank. The easiest way to get at it is from under the car. Clark's has a pretty good write up and drawings so about any moron can do the test, once you know what you are supposed to do, that is.

If this turns out to be the problem you are going to need a big deep well socket that you probably don't have in your standard tool kit. I think the flats on the sensor are around 22mm, maybe bigger. Order the new sensor and go down to the local hardware store with it in hand and buy the correct deep socket.

 

IceShark--
Thank you for the additional info. Yes, I checked out Clark's site, good details. I had used his site info to test the relay, with mixed results; will replace relay nonetheless, then proceed to thermofan switch if no satisfaction.
Really appreciate the help!
Greg

 

Greg, check the thermo fan switch first. That is usually the first to die. The relay is sort of expensive as I recall, like over 100 bucks, so you don't want to just buy a new one if the old is still fine

 

it's been 6 years, but i now have the same 2 problems, too... what were the resolutions?

 

+1, the day I got my 951, that sensor blew and the fans would not turn off. It a cheap sensor to replace but does require some new coolant.