Just replaced Alternator and now I have a battery light warning

Kemo · 02-02-2009, 08:41 AM

I just replaced the alternator in my 78SC with a rebuilt Paris Rhone unit with the internal regulator.

as per the technical bulletin, I installed a new ground wire. In the bulliten, it mentioned that I would need to install a resistor of sorts (91ohms, 5watts) if my battery warning light stayed on after starting the car. My light is on and I need to apply the fix.

the part numbers are listed as 911-641-981-00 for the resistor and 111-971-511 for something called a piggyback connector.

I called Pelican but they no longer supply these parts. I checked here in Austin at a few electronic stores with no luck.

Does anyone have a source for these two parts?

thx,

76carrera3.0 · 02-02-2009, 09:33 AM

Send me an E-mail and I will send you one in the mail. They are NLA so we have to make them up. No big deal the 91 ohms is why you can't find the parts I hade to use either a 95 or 90 ohm, I can't recall, either way I have a few left over, and I will send you one if you like gratis. They cost less then five bucks each to make up. Make sure as well that the ground strap connection at the alternator has not swung over to the other pole next to it, if it is a bare ground strap it can swing over and touch the other pole next to it as you tighten down the nut, its hard to see in there, again I can't recal the # of the pole but if it has, you will never get rid of the light on in the dash and you won't charge even with the resistor installed at the gauge. I found this out the hard way. Let me know how I can help you out.

Trevor.

john walker's workshop · 02-02-2009, 09:42 AM

did you remove the old regulator?

Kemo · 02-02-2009, 09:54 AM

Quote:

Originally Posted by 76carrera3.0

Send me an E-mail and I will send you one in the mail. They are NLA so we have to make them up. No big deal the 91 ohms is why you can't find the parts I hade to use either a 95 or 90 ohm, I can't recall, either way I have a few left over, and I will send you one if you like gratis. They cost less then five bucks each to make up. Make sure as well that the ground strap connection at the alternator has not swung over to the other pole next to it, if it is a bare ground strap it can swing over and touch the other pole next to it as you tighten down the nut, its hard to see in there, again I can't recal the # of the pole but if it has, you will never get rid of the light on in the dash and you won't charge even with the resistor installed at the gauge. I found this out the hard way. Let me know how I can help you out.

Trevor.

thank you so much for the offer. I will be sending you a PM with all kinds of contact information! The ground strap I used isnt a bare one, it has a nice plastic coating.

Kemo · 02-02-2009, 10:12 AM

Quote:

Originally Posted by john walker's workshop

did you remove the old regulator?

This is a rebuilt unit replacing a Previous Owner's questionable upgrade. My fan was rubbing and I pulled it apart to find out that the bolts had just worked loose. The alternator was set in place at a 45deg angle and there was no Air guide thingy. I decided to source a rebuilt unit to ease my fears, and install an Air guide cone. I followed the instructions on the technical bulliten to make sure I had the wiring correct, including a new ground strap. The PO had the upgraded alternator wired right, but the ground strap was too short. In order to get the alternator to fit, he rotated the unit about 45 deg to compensate. unfortunately, this would not allow the Air guide to fit in there as the fins would have probably hit the top of the shroud. So, im guessing they left it out. At least thats my best guess

I am assuming that this is when the original regulator was removed.

I found an air cone from a PP member, but I had to notch it to get it to fit over the regulator built in the back of the Paris Rhone unit. I mounted the Alternator inside the fan housing such that the regulator is at the bottom most location. I hope this is right, it seemed like the only way to get everthing to fit in there with the cone. I have one Black wire that is not used. The tech bulletin said to cut it off at the wire branch but I just taped it up with electrical tape.

76carrera3.0 · 02-02-2009, 10:38 AM

JW he is refering to the resistor that is required to excite the field windings to get the new style alternator to charge, as per the Porsche tech bulliten. It installs on the back side of the gauge in parallel with the connetions for the bulb if I recall.

76carrera3.0 · 02-02-2009, 10:41 AM

Sorry, John I opened my typing mouth before fully reading your statment, of course you know what your talking about, my bad!

304065 · 02-02-2009, 10:46 AM

You probably don't need the parallel resistor. I used a Carrera alternator in my '71 for a few years, the current through the "blue wire" was adequate to excite the alternator at around 1000 rpm.

When you start the car just gently edge the gas up over 1200 or so and the light should go out. If it doesn't, you made a wiring error or something systemic is wrong.

Don't goose the throttle to 6000 rpm or you will blow up the oil cooler.

Search here for "Early_S_Man" and "Zero-ampere RPM" for a thorough explanation of this topic.

john walker's workshop · 11:41 AM

some of those PR alts don't have any marking on the ground terminal and the D+/61 terminal for the blue wire which could lead to them getting swapped. if the blue wire is at ground, then the light won't go out. won't charge either of course. the B+ is obvious. i haven't had to install a resistor for the light in ages, so i kind of doubt that's the problem.

Kemo · 02-02-2009, 01:15 PM

Quote:

Originally Posted by john walker's workshop

some of those PR alts don't have any marking on the ground terminal and the D+/61 terminal for the blue wire which could lead to them getting swapped. if the blue wire is at ground, then the light won't go out. won't charge either of course. the B+ is obvious. i haven't had to install a resistor for the light in ages, so i kind of doubt that's the problem.

JW,

I really appreciate your input on this matter. Thanks a bunch. How could I check to see if the alternator is charging?

I have a basic FLUKE digital voltmeter but thats about it...

Kemo · 02-02-2009, 01:20 PM

Quote:

Originally Posted by john walker's workshop

the B+ is obvious.

this because there is one side of the alternator with only one pole...right? Im a little slow at times

304065 · 02-02-2009, 01:38 PM

Quote:

Originally Posted by Kemo

this because there is one side of the alternator with only one pole...right? Im a little slow at times

The B+ is obvious because it is the largest terminal on the back and says B+ right next to it, probably as a warning, as if to say, "don't connect anything other than battery positive to this or you will blow your electrical system and probably start a fire!"

D+/61 should be a ring terminal, small, maybe 5mm in size. Blue wire
D- is the ground, you should see continuity with the alternator case Brown wire
B+ as above Red wire

That's all there is.

john walker's workshop · 02-02-2009, 02:36 PM

attach the fluke meter and read the battery voltage. start the engine, raise the RPM and read the charging voltage. needs to be more than the battery reading. you should see 13.8-14.2V running.

RSTarga · 02-02-2009, 04:30 PM

has any one tried the australian K3 alternator that autofarm sells. Who sells them here?