944 FAN

Could someone please help..Ive been noticing that my battery meter gauge lately has been reading really low, actuallywhen i 1st start the car in the morning it reads close to the 14 range, as i continue driving it reaches close to 12 than it goes as low as 10..at this point om wondering if the car will shut off..The wacky thing about it, is that sometimes it shoots back up to close to 14..I know its not the alternator, and i just replaced the battery,im thinking maybe a fauly volt gauge..Could someone shed some light on this??????any reply's are greatly appreciated,its also a 89 944..

adrian jaye

Could be the gauge, there not known for there accuracy.

Best thing to do is rig up a Digital Voltmeter, into the cabin, with lead going to the battery, mine is in the Back so it's easy, otherwise if yours in the front you may be able to still do this.

Then all you have to do is compare reading's.

YOu could also rig a cigarette lighter lead to go to your meter as well.

Melchior

I fixed mine when it started doing that. There is a resistor in the back of the voltmeter gauge (in the instrument cluster) that gets corrosion on it over time. Simply slide the resistor out of its mount, clean its contacts with fine sand paper and reinstall it.

Adrian

Dear 944 Fan,
Whilst I agree that it could be the indicator itself it could also be the regulator assembly which is mounted in the rear of the alternator assembly.
One check you can do whilst driving is to apply different loads. Lights on and off, aircon on and off. Rear window demister.
Before replacing the voltmeter I would confirm 100% that it is no the regulator or a wiring problem. Have you checked all the wires on the battery positive terminal, since replacing the battery. Maybe a check of the earths or ground studs would be in order as well,
Ciao,
Adrian
911C4

Blue944Auto

Hey, there is a simply way of fixing the volt meter, e-mail me and i will send you and article that will solve all your problems on the volmeter gauge ( don`t worry, it will not cost you a penny)

IceShark

I agree you want to check the voltage with another meter while driving and see what happens. Just fish some temporary wires from the battery, through the window and into the cabin.

Adrian is also right that it could be the regulator. They are designed to cut down the voltage a bit as the engine bay gets warmer to prevent too rapid a charge to the battery. So the regulator could be crapping out and overdoing this feature.

I'm buying a bunch of regulators for some Rennlisters in the next week or so. If you want in they are $16.50 plus $4.50 shipping.

Marcus

Could this be due to not having the cooling duct attached on the back of the alt? Mine does the same thing and I noticed that the pipe was missing. I'm going to replace it and see if it makes a diff.

Cheers,

IceShark

Lack of the cooling duct would make the voltage drop down quicker but shouldn't cause erratic pops up and down in voltage. Other than lack of the cooling duct happened to result in your electrical parts wearing out quicker than they should have.