280 Alternator Upgrade - will Not Charge

[S30Driver]

1977 280z  the last year of externally regulated alternators for the z cars.   Over the winter I purchased some parts for the cars, one of which was the 60amp zx internally regulated alternator from Zcardepot to gain the reliability on the integrated voltage regulator .

This is a common swap that I am sure has been done a thousand times or more.  Of course, after removing my perfectly functional externally regulated alternator and installing the new one - no charge output.   I used Blue's well documented wiring diagram to unplug the regulator and make the connections on the 6 pin harness connector to jumper sense line and complete the circuit.   Pins 1 to 5  and 2 to 3 according to the 77 wiring diagram.

When this is done,  the alternator output is the nominal battery voltage ( about12.8 to 13v) obviously not charging.   I verified all the wiring and connections, the color code of the harness plug matches exactly to the atlantic z diagram.  Also when pins 1-5 are connected,  the charge warning light on the volt gauge comes on.

For fun, I removed the jumpers and plugged back in the external regulator  -  it now charges, looks like overcharges 14.8 - 15.5v

Its looking to me like I may have to uninstall the new one, take it to Oriellys to have it tested and go from there.

Other than a bad alternator or a externally reg one put in the wrong box,  anyone have any further suggestions to try and correct the issue or possibly I have missed something...

 

 

[Zed Head]

With the key on and engine not running check both pins at the T connector for battery voltage.  Sounds like your L connection is not complete.  If you confirm that there are several ways to find L and get it connected.  S will have power with the key off.  Might as well verify that too.

All the stuff you're doing at the old regulator plug is just for the purpose of getting L and S connected to the T plug.  Might be that you just had bad jumpers.  Check for S and L at the jumped plug also.

[S30Driver]

Will check those voltage points tomorrow.... thanks

[Captain Obvious]

Yeah, the first thing I would do would be confirm that it is in fact the correct alternator and that it tests good on the bench.

We'll figure it out.  (And if you get really stuck, give me a call.)   

[Zed Head]

Isn't it easier to stick a voltmeter probe in to the T connector while everything is installed?  The thing is already bolted up.  No T plug L circuit voltage  = no charging.  He already showed that it will charge with the old connections through the regulator so it seems like a lack of current on the L circuit.

He could even add a jumper wire from the battery to the L pin as a bench test.  Except the bench is the car.

[Zed Head]

20 hours ago, S30Driver said:

  Also when pins 1-5 are connected,  the charge warning light on the volt gauge comes on.

On further review I can see where things don't add up.  The charge light coming on implies that there is grounding through the alternator.  But it might not be.  The Charge light can ground anywhere.

[S30Driver]

Ran a voltage test with ignition on and regulator unplugged with jumpers 1-5  2-3 on chassis harness connector.  The yellow wire on the alternator T connector shows 12.65 volts (battery voltage) I believed this is the S connection.  It shows this voltage weather the ignition is on or off.

The white wire on the T connection with ignition on looks like it confuses the auto range on the meter, is probably 0 but floats up to 40 and then back down.  With ignition off it shows 0 volts.

The 2 short male pin jumpers I made for the female plug end are good.

[Zed Head]

Are you sure it's not 0.4?

Regardless, it should be battery voltage, disconnected, with the key on.  If you get in to the wiring diagram you'll see that the jumpers in the atlanticz diagram are just meant to route that Lamp circuit directly to the T plug.  You could short across the T plug and you'd have a "one-wire" system.  Your charge light won't work right though.  I think it might drain your battery too.

Even if you get it to work you might have a problem with the brake check warning lamp relay, draining tour battery.  I had the problem with my 76, after using the atlanticz diagram.  They changed it in 77 I think, but not sure exactly how.  It might be that the atlanticz diagram is not right for your car, maybe try the 76 diagram.  He actually puts a disclaimer in there, I think.  CO got deep in to the 77 and 78 waring lamp in a past thread. 

Eventually I just said screw it I need to know how this all works, and I ran my own S wire, rerouted the power to my warning lamp, and only used the L wire.  It's easy to check everything with a meter.  Find the L wire, confirm continuity to the L terminal at the T plug, jumper those two together.  Pick any S wire, there are 2 or 3 constant power wires at that plug, if I recall, jumper one to the S circuit at the T.  Overall, you just need to know which is L.  S is easy.

Here's a 1982 alternator drawing.  The wire colors are probably different but the positions will be the same.

Edited April 13, 2018 by Zed Head

[S30Driver]

Thanks for the feedback Zed!   Looks like I need to investigate the L wire connection.  My car is down at my garage/shop a couple of miles away & the weather is closing in today - severe thunderstorms, probably won't get back to it for a day or 2.

I did not disconnect the T plug when I checked the voltages,  just plugged the meter probe in from the back of the connector.

[S30Driver]

Update :

The alternator gods have finally smiled on me today!   After much troubleshooting, I decided to verify with the manufacturer the alternator part number and sure enough, the alternator sent to me was the externally regulated one instead of the later internal model.  ZcarDepot had put their wrong internal stock number on the box.  They agreed to send me a correct replacement unit which arrived today.

Installed the new alternator, unplugged the external regulator & jumpered pins  1-5   2-3  on the harness connector ..... no charge output.   More vom troubleshooting and after jumpering pins 2-5 only ..... voila ... charge voltage output.   Pin 5 is the white black wire going to the alternator L connection, pin 2 is the white red wire on the alternator output battery connection.   Ordered a plastic cap to weatherproof my jumper plug but was shipping delayed till Monday.

Problem appears to be solved.

 

 

[Zed Head]

So, pretty much everything that could go wrong, went wrong.  Weird!

Did ZCD pay for shipping on the exchange?

[Dave WM]

so how well does it charge? at idle turn on all the lights and fan on high brakes on, get a voltage reading (with a volt meter at the battery). Just curious as I have read this cures the brown out of the stock or is it just to get rid of the ext regulator. With my stock setup the fully loaded will result in a slight discharge at idle (about 12v at the battery when typical battery voltage with everything off is about 12.8). As soon as I get over about 1.2 k rpm all its ok (no more discharge, about 13.5-14v at the battery).