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Change to externally regulated alternator

561 Views 18 Replies 9 Participants Last post by  blue
All the posts I see on alternator upgrades discuss changing early Z cars external regulation system to adapt to an upgraded internally regulated alternator. Why not just take an internally regulated alternator to a shop and have them change the regulation to external, and leave the wiring alone in your car?
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It would seem to me that it would be alot easier, and probably cheaper to just change out the Alternators... I actually had bought an internal alternator but wanted to be... um..Pure, so I took it back. Cant see spending money to have a shop do anything... but, thats just me.
The wiring is so easy that it doesn't justify doing that.
Even me, who was completely ignorant of electronics, figured it out in 15 minutes!
Plus doing so will get rid of that regulator box and you get a cleaner looking feder wall. (minor but a noticeable difference)
Most older alternators are internally regulated and have a low amperage rating for a z. For the people who need a higher amperage alternator they use an internally regulated alternator: G.M. alternator, a later model Maxima alternator, or zx alternator. Update the harness a bit and they then have more than enough amps to use all there accessories, stereo system amps or whatever.

Dexter 260
I swapped an internally regulated ZX into my externally regulated 280Z and it still is wonky but works.

I measured battery voltage at battery and at regulator, looked at signal on a scope, measured loss in all cables between battery and alternator. Belt is tight. Can't find a problem.

It still does not lock into a voltage at idle (~ 1000rpm). At start the gauge goes from 12V to 15V and is stable for about 6 sec then the gauge drifts quickly from 13V to ~15V and the charge light flickers. I can hear the fuel pump droning to the same fluctuations. When I rev it up the voltage stabilizes or after driving for a few min it stabilizes.

I am guessing it is a bad alterntor. The older alternator and ext. Vreg did the same thing but much slower and the charge light never flickered.
Hey Blue...

Where do you have your voltage sense wire hooked up to?

I'll have to check my tech tip (1 sec).

I think it goes straight from alt to bat+ with low resistance (<1 ohm)

I am now looking at the Z-Creations Tech Tip (which I followed) and the wire colours they claim are at the pins 1-6. They are different from the colours on my car's connections and on the Zcar wiring Diagram.

Dang Dang Dang... can't trust anyone :(

Pin 1 on my car and wayne's diagram is blue and goes to Vgauge, Zcreations say it is white and red!!! <http://www.zcarcreations.com/howto/voltreg.htm>

I'll grab my volt meter tomorrow and see what is going on :(

Thanks for prodding!

Post Edited (Oct 23, 6:44pm)
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I think this is the problem:

Zcreations say to connect the Sense wire from the Alt (pin 3 at the Vreg connector) to pin 6 at the Vreg connector white/blue (a true +12V ignition source)

In fact it should go to the battery which is Pin 2.

Right now the yellow sense is connected to a signal that hits the gauges!!!
Gee Blue...thanks...Now I feel better about keeping my externally regulated Alt. .... When I bought the internally reg. alt, it looked pretty simple, but...as you know...Im almost a purist! Youve just sold me on staying with the external VR. The last thing I need is more electrical troubles! :eek:) I do keep an extra alternator and VR in the closet, just in case! :eek:)
I had trouble with a friend's 240 when he converted to a single wire GM alternator. The wiring was easy enough until we switched motors and he decided to go to an electric fuel pump only. (The 73 came with an electric and a mechanical pump) The fuel pump relays are actuated by a signal that comes from the alternator....when I tried to just run a wire straight from the new alternator to the relays, it didn't work right. The whole deal kinda teed me off. i don't think these conversions are an upgrade at all; they are expensive and are not any more reliable. I would never do one unless I needed the extra power...which I don't.
jazzbug - Good one! Looking outside the box. Makes good sense too.
You'd have the later year, higher output alternator and a bolt in swap.
Have the shop do two so you could have a convient spare replacement ready.

I've seen instructions somewhere on what you phiscally need to do to change the charging curve of the regulator (remote power generators - gasoline engine driven) and the internals didn't look too complicated so I'm betting the internal regulator could be easily removed or bypassed without going external and hacking into your car's harness.

Edited .......

But wait....... the external regulator probably isn't designed/rated to handle the bump up from say a 50 amp alternator to a 100 amp alternator. Might have a regulator fail as it tries to pass twice the original current.

Post Edited (Oct 24, 12:07am)
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Is there ANY benefit to going with an internally regulated alternator? Any at all???
Probably not as much in an automotive application because one aspect - line loss - would be irrelevant. From a cost standpoint for the industry - less materials: wires, connectors, less inventory/storage, one assembly.

But for us end users the only one I see off hand is the need to retrofit a smaller capacity alternator with a larger one, if the load is increased, and a more robust external regulator hasn't been identified for the larger alternator - maybe someone else will chime in.
Pin 1 on my car and wayne's diagram is blue and goes to Vgauge, Zcreations say it is white and red!!! http://www.zcarcreations.com/howto/voltreg.htm
Take another look at what they are referencing. I looked at the colors of the harness, they are exactly as the FSM states. Looking at the connector and subharness from the VReg, they are exactly as zcarcreations state they are.

The FSM did not state what colors the harness off the VReg were, so it was a 'best guess' when the colorized diagram was published - I did not go and verify every connection.

It appears that zcarcreations is assuming that one is making the changes to the VReg side of the connector, of which, the wire colors are stated correctly.

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Thanks Wayne!

The change in colours got me however, I did connect the correct wires as per their instruction.

I think yellow (sense) on pin 3 should go to the white with red stripe (battery) on pin 2 rather than to the (ign) pin 6 which goes through the fuse box and dash instruments as this signal is probably corrupted.

I'll change it now and see what happens

Post Edited (Oct 24, 2:41pm)
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FIXED!!! I connected the alternator's Sense wire (yellow) to a good +12V battery signal and now the voltage is locked at 14.45V at all rpms. It is rock solid :) Finally!

The Zcreations tip is not ideal. The sense signal for the alternator must come from a good +12V battery wire. The one they suggest in the tip is just too poor for the job.

I updated my tech tip.

Happy dude!
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