GM Alternator Woes

[Zed Head]

I'll bet the diagrams they used for the Z are from passenger cars and trucks that don't have a fancy ammeter, but that did have a light.  

Looked again and it does look like the W to the regulator, which would be the original L (BW at the alternator) wire, comes directly from the fusible link.  So it's a direct 12 volts, no resistance.

If the GM guys say you need a resistor you probably better install one.

Edited October 22, 2016 by Zed Head

[Zed Head]

Just for fun you could measure resistance from the L pin to the alternator case (ground).  If there's 50 ohms or so, then the whole "need resistor" thing might be bogus.  Madelectrical seems to be the only site saying it's needed.  Sometimes things can get parrotted all over the internet if they're said with authority.  An exclamation point has amazing power.   !

[Zed Head]

Last comment - I read a few more web pages.  If I were doing what you're dong I'd find out what all four of those pins do.  Could be that you need both L and F to get things correct for the CS144.

Edit - just saw somebody say the "F" stands for Failure indication to the ECU.  Kind of fits the wiring image above.  They're mostly all saying also that the the L circuit in the alternator is low resistance and the wire needs outside additional resistance, to avoid overheating/failure.  So, add a resistor the L wire and you should be in business.

Edit 2 - way down this page the guy, who seems to know some things, says the resistor is used in a parallel line.  This actually makes more sense.  People may just be warping and assuming things they read, in their head.  http://www.pirate4x4.com/tech/billavista/Wiring/Part2/

I'd just measure resistance on the L to case circuit myself, and if it's above 50 ohms wire it up and run it.

Edited October 22, 2016 by Zed Head

[HuD 91gt]

Thanks for doing the research.  The original 4 pin layout explanation was off that pirate4x4 site as well, but on the forum.  I missed that write up, that's a good one.  Unfortunatly this is going to have to wait until mon/tues to solve this riddle now.  I will do as you say, and check the resistance in the circuit, will have to purchased a new multimeter as mine gives bogus resistant readings.  I also purchased a 46ohm resistor which should do the job nicely.

Once again, really appreciate the help.  I think we figured out this problem.  I will update you all.

[HuD 91gt]

Well, I didn't have a properly working multimeter (resistance readings are way off), I wired in the small resistor and switched to the other prong as discussed above. 14.6v at idle! Wowsers.

 

We'll chalk this one up as a success story.

 

Edited October 25, 2016 by HuD 91gt

[Zed Head]

Good deal.  Better check at higher RPM also to be sure the Sense wire is connected to the regulator, and the regulator is regulating.