Dahveedem

996 4S Cabrio, 6spd, X51 package, PCCB
I've searched the forum even using google search and can't seem to find the answer.
I've been having some odd electrical issues, new coils throwing cels, ABS/PSM light coming on and recently flickering lights and the voltage meter jumping between 12 and 14.

Everything I've read online indicates the flickering lights are a bad VR. I had the battery tested and the charging tested and the tool came up indicating the VR failed.

Here's what I've done

Replaced all coils (did find one bad coil after swapping them around so replaced that one)
New Bosch plugs.
New Brake switch
Cleaned throttle body
new MAF
New Battery

Decided to go ahead and give a new VR a shot.
Ordered a 000-043-206-37-M14 / Bosch F-00M-144-136 from Pelican as it said that was the right VR.
Replaced the VR in the Alternator and bench tested it. All looked good.
Put back in car and now the volt meter is at least going to 14 but it's still jumping and the lights are flickering. It's also throwing all sorts of misfire codes now.

Double checked the part I pulled from the Alt. it's actually F-00M-145-225

I've seen some references where the 136 is the right VR and some where the 225 is the correct VR.

It would be good if the answer is "hey Pelican has the wrong part listed" and I'll just order the right one.

Worst case --- what else am I looking for here?
I did check the grounds and they all appear ok.

Sorry for the duplicate post if it is one... feel free to bap me up alongside the head and point me to a post where I can find the details

Thanks in advance for the help.

D

Ahsai

If the flickering can be reproduced easily, you may want to check the alternator output directly at the back of the alternator. Use a stiff insulated wire and bend it to a small hook shape. If the voltage drop is at the alternator, your alternator is bad. An alternator has components other than the VR that can break too (e.g. the diodes).

If the output is steady but your voltmeter shows 12-14v fluctuation, you will need further voltage drop test between various points along the path between the alternator and the battery to check exactly where you lose voltage. One major suspect is the y-cable.

All the above assumes you use a multimeter and not just relying on the voltmeter in the dash.

hatchetf15

As Ahsai points out, what gauging are you using? The dash meter, a multimeter? So you already checked grounds with multimeter? Have you checked the cable runs from the battery tray to the ground and alternator (y cable)? Loose bolts and corrosion checked (y cable) under the car and around the engine? Bad diodes...maybe. Any codes thrown as determined by an OBD 2 reader? Did anyone mention the y cable? Kidding Ahsai. Ahsai has been telling folks to check that forever. Probably half don’t know what or where it is.

Dahveedem

When I replaced the VR, i took the alternator to a shop and they bench tested it including load simulation. Passed with flying colors.

Didnt see any corrosion on the grounds. Even pulled the main grounding strap and scuffed it up.

You mention a Y cable... not sure I know where or what.

So you think the VR is correct or maybe just bad?

Ahsai

I suspect you have a loose connection somewhere. Check out this diagram and make sure all the nuts of the connections are tight. Starting from the battery positive post and cable to the power distribution, then under the car via the transmission tunnel to the engine positive jump terminal (above the a/c compressor), then to the y cable, then to the engine ground behind the right rear wheel, then back to the negative battery cable and battery post.

https://www.renntech.org/topic/47504...arging-issues/

Dahveedem

Thanks for the tips and test list.

All showed numbers under the specs you indicated.

So I'm back to a bad VR? Even though the bench test showed was ok?

Also i mentioned the VR is a different part number than what I pulled off the car. Is it possible the X51 has a different alternator and VR in it?

Splitting Atoms

When I bought my 996, it was a local Craigslist "bring a trailer" car due to electrical issues the previous owner and his shop could not resolve. It had multiple lights on the dash illuminated. I don't remember which one's, specifically. I trailered it home and found the spot where the ground cable from the battery connected to the body was corroded. I cleaned it up, installed a new alternator, and all the lights went away. The bad ground had caused the voltage regulator in the alternator to fail. It had also killed the battery, but the PO had installed a new one shortly before I bought it.

Dahveedem

Quick update since the VR installed.

I did retest the connections and found the ground strap at a .3 V drop. Pulled it, checked it and it all appears tight with the plastic shrouds on it. I took a bristle brush to it as the mount on the engine looked a but "crusty".

Retested and it's down to a .1V loss.

No CELS since all of this and while not scientific the dash voltmeter holds at just above 14 above idle. No abs light either. I've also been aggressive running him.. I did that in the past I'd get misfire CELS.

At idle it jiggles between 12-14.

All the connections still test ok.

Not saying its fixed... but thoughts?