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280z with CS144 Alternator Swap: Alt cuts in and out at idle and a bit above.


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'96 Cadillac Deville alternator (CS144 clone; Autozone non-gold) swap into my 1976 280Z done back in 2009 worked flawlessly until a couple months ago.  Followed these instructions: http://forums.hybridz.org/index.php/topic/67531-ac-delcogm-alternator-swap-part-2-cs144-installation/

 

In February the alternator started dying completely.  Exchanged it under the lifetime warranty at Autozone.

 

Put in the new alternator.  

 

First thing I noticed was that when the ignition was on, but the car was not running, the CHG light on the voltage gauge wasn't as bright as it was with the first swapped alternator.  It used to be very bright, as bright as my speed "Brake" light.  Now it's dim, to the point you can't see it during the day very well dim.

 

The big problem I'm having is that at idle, the alternator will just stop charging for a couple seconds, then start, then stop, repeat.  It'll still try to stop charging even a bit over idle.  I have to be cruising to get it to stay on reliably.  I've tried exchanging this replacement alternator for another replacement but I'm having the same issues.

 

The first alternator from 2009 never gave me problems until it died a couple months ago.

 

I am using a 4ga wire from the Battery terminal on the alternator directly to my Costco/Kirkland battery, which is the same battery that was eventually paired with the first swap from '09.  

 

I believe I'm using the Sense and Light leads from the alternator through the Z's original harness, but not using the Field wire for anything.  On the Light wire, I have no resistor because the voltmeter has the charge light built into it (which is dim when the car is switched on without running).

 

I'm also using the original Datsun pulley.

 

Thoughts on where to start?  Is there a way of measuring resistance on the alternator and seeing if it's out of spec?  The dim charge light makes me think something in the alternator or similar has too much resistance.

 

Oh, also, if I pull the battery terminal when the engine is running, the car dies if the alternator switches off (as expected- except the alt shouldn't be shutting down).

Edited by Hardwyre
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Be certain it isn't your battery causing you problems first.  Reading this you state that the battery is from 2009 when you originally did the swap of the alternator.  That means the battery potentially is well over 5 years old dependent upon how long it sat on the shelf before you purchased it.  Also, why not jump the "SENSE" terminal on that alternator right to the battery stud instead of letting it travel through 30 year old wiring?  Unless you want the benefits of a remote sense terminal (long discussion but has benefits). Also, whats your voltage at your battery compared to your voltage at your "IGN" terminal, I've seen issues where the key tumbler cut the 12v to the IGN terminal and caused intermittent issues?

 

You have 1 of 2 things causing you problems.  A bad battery.  Or bad wiring,

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Thinking of the battery, it does seem to dump down to about 12 volts when the alternator turns off.  If the battery was doing okay, it would have some charge up into the 14's until it had a chance to dissipate.  I'll get the battery check or try swapping my room mate's to see what she does.

 

I didn't realize I could just jumper the sense to batt; but that is a great idea as well.

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I never had issue with the Z's pulley on the alternator.  It looks rather large but it is a v-groove versus the serpentine belt setup on the CS144.

 

Don't discount that you got a bad alternator just because it's new.

 

If you turn the key off the battery will drop to around 12.7 volts; it does not hang at 14 volts.  If your battery drops to 12 volts then it is nearly discharged.

 

Have you measured the voltage at the back of the alternator while the car is running?  Have you measured the voltage at the sense wire while the car is running?

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Well son of a.. so all this time, I had the sense wire connect to the black ground.  I have no... 

 

So I tried connecting it to the white wire which appears to go directly to the battery through the fusible link.  The problem is, now the battery is charging as high as 15.8 volts at the battery.

 

I'm going to try wiring it to the proper yellow wire now and see what it does.

 

Can I have damaged the voltage regulator by having the sense wire connected to ground?

 

I'm surprised the first alternator worked so well for all those years.

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Okay.  Tried the thick white wire that I think originally was the battery wire.  15.8 volts.

Tried the yellow original sense wire.  15.8 volts.

Tried no sense wire at all.  14.8 volts.

 

When the car is off completely, the white wire and yellow wire both show battery voltage of 12.7.

 

Going to have Autozone order in a gold (new) alternator instead of using a reman.

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