Bush Pilot

What I’m experiencing could best be called a “brown out” of the car’s electrical system when an additional current load is put onto the system. The symptoms are as follows:
-flickering lights
-stumbling engine operation when high current load is introduced such as a stalled window motor or operation of the bright lights
-Uncommanded radio power cycle
-etc

Measured data I’ve gathered:
- At rest battery voltage 12.4
- Running battery voltage 12.6

I know that the previous owner was doing something in that he instrument cluster area before I bought it.

My suspicion is that there is a loose ground and I’ve been looking for that but haven’t found one. The car has 49k mi and is an AZ car so doubt its a corrosion issue. However I haven’t looked inside the instrument cluster.

I bought a new regulator for $50 and was thinking of installing that just to try but I’m not hopeful.

Maybe it’s time to pay the Porsche Dealer to inspect it? Thanks for any thoughts on a path forward.

Geza

Inside view looks just like my '97, including the airbag light! Check the ignition switch - jiggle it. The 1997 had bad switches subject to a recall, as I recall. Many folks switched them out at the time for a VW/Audi switch. I still have the original, and have learned to live with it over 25 years. In my case, when I turn the key to start the car, the switch does not spring back fully to the "on" position; I have to do it manually, and if I don't click it back to "on" properly, I have electrical issues.

Bush Pilot

Thank you. That's a good lead. I'll give that a try and report back.

tcora

12.6V sounds suspiciously low to me.

Bush Pilot

Yeah. Me too. I thought that in the past when the car wasn’t in the brown out mode it was above 13 V. I’ll make more measurements and wiggle the key around as was suggested. Thanks so much.

Bush Pilot

I wiggled the key around and that didn’t seem to have any effect. The car has 50k mi so maybe that’s not worn yet? Previous owner was a fat fingers though.

I measured the voltage at the battery and it’s now 13.6V but was a steady 12.6 when the brown out condition it occurring. I’m thinking that at this point I should go ahead and replace the regulator on the alrernator…..please talk me out of it though if you think it’s a waste of time.

tcora

Replace it! Have the battery load tested as well.

Bush Pilot

Good addition on the battery checkout. That’s so easy so why not.

tcora

exactly what I was thinking

Bush Pilot

I got my alternator out today and attempted to replace the regulator. The two screws that appear to hold the voltage regulator to the alternator body appear to be permanently held in place with a permanent thread adhesive because I ended up twisting both screws off and leaving the threaded portion in the alternator trying to get them off. So I guess I’ll order an alternator tomorrow once I understand who pays the shipping for the core.

tcora

The thread adhesive is likely 26 years (yours is a 97, I think) of a steel screw threaded into aluminum. Dissimilar metals… a bit of careful drill work might save the day. Worst case, you end up with a new alternator.

Bush Pilot

Thats a good point to try to remove those, at this point, steel threaded rods fused in some manner to the alternator. At this point replacing just the regulator to try to isolate my problem is too difficult. Afterall, some other component of the alternator could be causing the brown out. I’m leaning towards a new Chinesium one (not rebuilt) for $249 and my core doesn’t have to be shipped at my cost. I hate to say it but going Chinesium on this repair may be the best path forward…..but where does that path end??? LOL! FYI my wife is Asian and I love her.

tcora

I hear ya!

Bush Pilot

So I replaced the alternator with a rebuilt one. The voltage at the battery with the engine running is now 14.5V vs the old alternator was 13.6V (both voltages are within acceptable range) and when the brown out was happening the voltage would be 12.6. Only time will tell if the issue has been fixed. One thing I'm noticing now that wasn't happening before is that when I turn on the AC compressor the idle automatically rises by about 200 rpm and that wasn't happening before.

tcora

Quick question - where are you measuring the voltage?