PSD21

About a half mile after leaving my garage this morning my entire instrument cluster loss all power (No Speedo, no tach, oil press, gas level, etc) and the only light illuminated was the alternator/battery light on the clock. I was only going down the street to my community fitness center so I continued there and then back and the car seemed to run normal but again no gauge indications. After getting home I then noticed that the climate control unit (fan and A/C) wasn't working and had no power, and the rear spoiler would not manually raise or lower. The windows, headlights, and radio all worked fine. With the car off and the key turned to the on position there is no gauge indication or any of the lights normally observed prior to turning the key to the start position. There are no warning lights of any sort. When I start the car the alternator warning light then comes on and no other. The car starts with no problem. I recently replaced the alternator about 10,000 miles and six months ago, so my first thought was to not want to believe that is the problem (it was a bosch refurbished unit from pelican). I am not certain on the age of the battery. Pre-start battery voltage is reading ~12.5V. After starting the car, voltage reads about 11.5V. If I hold mid-level, about 3 to 4RPM, revs (guessing since the tach isn't working) for about the 10 second the battery voltage then reads 13.5Vn and appears to hold steady. I would expect some where around 14.2V with the car running if I am not mistaken. I also checked the tension on the alternator belt and seems fine. The voltage readings seem to point to a problem with the voltage regulator or bad alternator all together but I don't understand why none of the gauges or other indicator lights work with the car on or off even if the alternator is bad. Could there be some kind of problem with the onboard computer? Has anyone ever experienced anything similar. I did a search and wasn't able to come up with anything. I am also new to the Tampa area and was wondering if anyone could recommend a good mechanic. I am guessing I am going to have the vehicle towed somewhere. I would hate for the car to overheat and not realize it while driving since I have no indications and the spoiler doesn't raise, oh and it's about 90 degrees here. Any help before I have to go down that road would be greatly appreciated.

tonypai

Did you check the fuses? A quick, simple and inexpensive solution before you pay for a tow.

PSD21

Yeah. All fuses are ok. The only other thing I can guess is possibly a control relay, which I am not really equipped to check.

Davies

Hmmm - the magic fix-all for most 993 electrical trouble is to install a shiny new battery ground cable. Is your car a '95? If so, did it have the wiring harness recall performed at some point?

PSD21

It is a 95. The problem seems to be intermittent now. After posting I started the car to head to the local Porsche dealership, and the problem was gone. I only owned the car for the past year and I don't have any record of maintenance for the wiring harness. That said I have never had a problem of this sort at all. The service department did say that would be the first thing they would check. Is the wiring harness a notorious problem in 95's? I haven't ever read about that one.

KMASS993

Try the R11 relay. It's cheap, replace it and see if that works.

Marco8

Have a dealership run a history on your car. It will show if the wire harness recall was performed and when.

DanL993

AND become a memeber. Regularly checking this site is the BEST way to find out all about your car.

It will be the best investment you've made--since the car!!

KMASS993

Why waste your time at the dealership... you don't trust us?

No dealership, R11... I speak the truth!

https://rennlist.com/forums/993-foru...?highlight=R11

Jon Davis

I had exactly the same problem myself . . . my inital cure was to 'bash' the top of the fuze box under the hood. This actually worked. I then started investigating relays (in the same box that I had been 'bashing') and found that one of them was faulty, though I can't remember which . . . I think I just pulled them out one at a time to see what was affected by a lack of relay which worked me to the relay that fed the dash with power. I then swapped in another relay, from the sunroof I think, and the problem went away. The new relay cam from a VW dealer as it was identical to the Porsche one in everything but the price.

I'm pretty sure this will solve your problem.

ToreB

Haha, remind me of the days when we bashed the telly to correct problems. That really stirred the orange glowing tubes inside!
Regards,
Tore

PSD21

Thanks all for the tips and advice. Unfortunately, the dealer has informed me of that the central control unit has faulty output and needs to be replaced. I hope they have it correct and it wasn't only the R11. The part itself isn't too expensive but with labor (programming) and inspection looks like I am in for around $1000.00. I guess that is usually the case when go to a dealership...or at least in my experience and sometimes regardless if it's a Porsche or a Toyota. Fortunately, I will say that the Service Manager has done a great job keeping me informed, getting my car looked at quickly, and extended a 15% discount since I was prior military. The dealership is Reeves Imports in Tampa. So far, I would certainly recommend them if anyone is curious about their service.

KMASS993

You should try replacing the relay first and then see if happens again... hate to see you spend $1000 on the stealer when you could be spending it on MODS

P.s. My friend owns/service manager at a MB dealership... up-selling customers is the standard in the dealership world. I would be weary.

Zba

As a dealership employee I feel the need to comment. We don't "upsell" a component when the customer comes in for that specific problem. Upsell would be tires, service, brake flush etc. etc. etc, and only after the initial problem has been solved.
Chad

JStuart

What was the final outcome of this? I'm having the exact same symptoms on my 97.

J