I just bought another 928. It is an 81 euro 5-speed. I really love the thing, despite the fact that it is metallic brown. Anyway....I have been driving it, and the alternator gauge was reading barely above the 12V mark (constantly), just touching the mark. It was running perfectly. But, I deciding that I ought to replace the alternator to be safe. The new one is on, and I have cleaned all contacts on the car, and the alternator is grounded great. However, it is still giving the same reading at the gauges. Surely the car is being charged. What do you think? Just the typical thing the 928 gauges do?? Need a new battery? What??

 

I - I suggest that you get yourself a handheld Multi-meter (Volts-Ohms-Resistance). Sears sells some inexpensive meters as do many others. The volt meter in the dash is more of a gross voltage measurement. You really need to get a voltage measurement at the battery terminals to see if the alternator is charging properly. Get the engine running with a few accessories (headlights, blower fan) turned 'ON' and take a voltage measurement across the battery terminals. You should get at least 13.5 Volts if the battery is to charge properly. There are lots of ground points to clean which have been discussed several times on this board which is another place to start. Good Luck!

 

Just a couple weeks ago there was an extensive thread on the same problem. Search the archives for alternator and I'm sure you find some help.
I suspect the resistor on the volt gauge on the rear of the dash pod is the culprit. If memory serves me, it about a $6.00 part from one of the bug 3.

 

Is 928waSP one of the bug 3? <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />

 

If you check your voltage at the battery terminals and it is OK,and the resistor is still reading it's correct value, there is an adjustment pot on the gauge that can adjust the voltage reading to a more appropriate level. With a new alternator in my car and a new resistor, good grounds, 14 volts charging at the battery, my car would still read below 12 volts. After adjustment my gauge normally will read 2/3's between 12 and 14.

<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

 

Mr. 20/20 Hindsight here...
Go to the Greg Nichols site, then Electrical, then Alternator.
Read all and you will be the newest - right behind me -expert on alternator, diagnostics and repair.
<a href="http://nichols.nu/tips.com" target="_blank">http://nichols.nu/tips.com</a>
Jim Morehouse has an especially definitive procedure with drawing(s).
Read em' all!
Sorry you scrapped an alternator without testing,
Learn from the burn. <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" /> <img border="0" alt="[thumbsup]" title="" src="graemlins/bigok.gif" />

 

So....I tested at the battery. With the car off the battery was just over 12.5V. With the car on, the meter showed just over 14V. Does this mean that everything it good? Ther car runs great, new alt, all measures well. One thing I noticed is that the meter shows about 1 less volt if I have been driving for awhile.

 

Ah, someone as lazy as me.
Basically, the 12.5 and above with the engine off doesn't do anything for me...heck you could have a bad cell and still get above 12 volts from a
'surface charge' reading.
You should do the check with car running, then with car running turn on the lights, a/c, or , heat, light a cigar...
You want a good draw to your accessories and then test.
Read those Nichols post's I believe they even have a check at the Alt. while running. And as a Plus some are referenced thru Wally of esteemed Guru status and I think there was one reference from the lurking guru -Ed Ruiz-.

 

I did run things, and the voltage sits at over 14.5....I think that is good....How is that weissach doing John?

 

Alt. news update!
Finally, came in!
It tested o.k.
That was tuesday ...we worked till dark ...
Wednesday, someone couldn't make thier mind up at
the Airport off-ramp and went thru a rare stand of tree's, and a long row of shrubs.
Worked till 7:15, just in time for a little Texas wind. 25mph with gusts to 47mph
Thursday... yesterday's wind was just a breeze...35mph, gusts to 55+.
These winds generally, move either the the Pecos onion/melon fields, or the Amarillo/Lubbock terrain to Midland/Odessa by the ton.
I have to clean Pattycakes before something starts growing on her.
Even indoors the dust is so bad you can do more damage than good trying to do maintenance.
I'd rather die as roadkill in Pennsylvania than a Millionare in West Texas.
Though we do have some haul *** roads here.
She's trickle charging now to prevent diode/regulator death on the new alt. Tomorrow or Sunday I hope to be shredding the unwary at night...once again.
Sounds like you have a handle on the voltage...
might want to see if you can do that behind the Pod dash pot adjustment. It'll give you some peace of mind when the sun's going down 200 miles from the driveway.
Speaking of Weissach's how's yours?