260Z Alternator Voltmeter Swap

[Ed260Z]

I did this swap inorder to get rid of the external regulator. I got an early 280ZX alternator from my parts store, but there are others that you can use.

 

For the alternator swap go to www.zcarcreations.com (great directions). You only need the diode if you are installing an alternator with more than a 70amp rate. I took the regulator apart so that I would have plenty of wire at the end of the plug. I'll cut it to length after everything is running right.

 

Now lets install the Voltmeter from a 280Z. I decided to keep the Shunt (Since it does not allow the full amps to go through the cars wireing).

 

1) Unplug the the small connecter from the shunt, these wires supply the power to the Ampmeter. Pull one of the wires from the plug. I pulled the soild white white one from the plug, but it does not matter which one as long as you remember.

 

2) Then pull the disconnected wire out of the the rubber boot, and plug the connecter back into the shunt. The one still connected to the shunt will be your power wire for the gauge.

 

3) Connect the disconnected wire from the shunt to the unused Black wire from the Alternator conversion. This is now the ground for the Gauge.

 

4) Remove the wires from the Amp/Fuel Gauge and transfer them to the Volt/Fuel gauge. The Fuel gauge wires are identical. Use the light from the amp gauge on the volt gauge.

 

5) To attach the wires to the Voltmeter side cut the Wht/Red & Wht wires, leave them long, and atach them to the Voltmeter gauge. The Wht/Red attaches to the wire with the red sleeve on it. (Power Wire). And the Wht to the Blk wire(Ground).

 

6) Plug it in and make sure everything works. DONE!

 

Sorry no provisions for the charge light, since I could not get it to indicate properly.

 

This allows you to use the cars stock wireing, and is very simple to do. If anyone out there has done this before and knows how to hook up the charge light please let us know.

[Ed260Z]

Well it seems that the 260Z is the Red Headed Stepchild of the Z family. Iv'e had to make a revision to the conversion as outlined by Z Car Creations. On the 260Z the #2&3 wires should be connected not the 2&5. This allows for the alt to get the proper signal, and regulate the voltage properly.

 

The Elec fuel pump has stopped working, and the Alt will not get excited until it gets to about 3.5K RPM. (I think this has to do with the lack of the charge light, that provides some resistance.)

 

I've emailed Phil (Blue) from the Atlantic Z Club in Canada to see if he has any ideas.

 

But if any one has any ideas please chime in.

[Ed260Z]

Anyone????????????????????????????????????????????????

 

I know there more than a few 260Z owners on this site. And with all of the knowledge floating around someone must know, or think they know, how to get this done.

[zcarnut]

I have installed the 90A Maxima internally regulated alternator in my 260Z. I removed the external regulator and its connector and rewired the alternator so that the A terminal is connected to the battery positive terminal through a heavy gauge wire, the S terminal is connected to the battery positive terminal through a smaller gauge wire and the L terminal is connected to a +12V switched (IGN) source through a diode (so it can be energized at engine start up).

 

However you have to do more. The problem with the 260Z with regards to the elimination of the external voltage regulator is that it has an electric fuel pump shut off relay and it also has the seatbelt "interlock" module. Both of these circuits require an electric signal input so as to be able to determine whether or not the engine is actually rotating. This signal is supplied from a connection on the external voltage regulator.

 

On the 260Z there are two fuel pump relays in series with the rear-mounted electric fuel pump. One of these relays will not allow the electric fuel pump to operate when the engine is being cranked over when starting. I don’t know the purpose of this feature, but since the stock 260Z also has a mechanical fuel it can still supply fuel to the carbs when cranking.

 

The other relay is to shut off the electric fuel pump if the engine stops rotating. This is a safety feature in case of an accident where you could rupture a fuel line. Although the engine may stop, you would not want the electric fuel pump to continue to feed a potential fire.

 

The early alternators have an "N" terminal which is the common connection to the three stator windings. When the alternator is rotating there is a positive voltage induced at the "N" terminal. This is used to operate the "cut out" relay in the external regulator.

 

However, Nissan also used the "N" terminal voltage as a sense voltage to determine if the alternator and therefore the engine was rotating. The "N" terminal voltage operates the fuel pump relay and also sent to the seatbelt interlock module. This is done via an electrical connection off the external regulator (which has it's own connection to the "N" terminal of the alternator).

 

On my 260Z I elected to defeat both the electric fuel pump relays. So, the electric fuel pump operates whenever the ignition key is in the ON position. I have triple Webers and I like being able to prime them before starting the engine. These relays are located in the passenger side kick panel area.

 

However, I don't feel comfortable instructing someone to disable this safety feature. So, do what you want to.

 

I surmise that the seatbelt interlock module needs to know if the engine is running so you can unbuckle your belt while the car is moving without the engine being shut off by the interlock module.

 

I also defeated the seatbelt interlock module, as I don't need to be reminded to fasten my seatbelt. Nissan stopped using the interlock module in '75, and even told dealer service departments to defeat it on the 260Z if the customer had problems or complained about it.

 

It is probably possible to design a circuit that would have an "engine rotation" output signal when using the later internally regulated alternators. On the later Z cars Nissan used a special oil pressure sending unit (with two terminals) that supplied a voltage when the engine was rotating and generating oil pressure. The fuel injected Z cars needed this because it is possible for a fuel injected engine to operate even when it is upside down, say following an accident in which the Z rolls over on its top. However, in an inverted position the oil pressure would fall to zero as the oil would flow from oil pan to the top of the engine.

[Ed260Z]

OK I got the alt to start charging @ 1200 RPM. This is what is also stated on the Alt spec sheet.

 

How your asking? (for what seems to be the very few who want to know)

I used a Diode between the 1&5 wires. Then connected one end of a bulb to those wires and the other end of the bulb to a Ign "ON" power source. Now this acts like a Charge Light, and provides resistance to the circuit. This resistance excites the alt into making power. Once the Alt is "on" the bulb goes out.

 

I'm not sure if the diode is actually doing anything though. But that's how I tested the circuit, and if I upgrade to a higher AMP alt I will need it anyway so it will stay.

 

Now I just need to figure out how to get the fuel pump to work right.

 

 

 

Thanks Carnut for your input. You got me to realize what I was doing wrong with the Charge light circuit. Although I'd rather not lose the safety feature of the pump shut off, personally.

[Ed260Z]

The charge light needs to be connected to the #5 wire. So at the very least the diode keeps the current seperated between the two. And the charge light functions properly.

[Guest 305240]

This is a great read. Very interesting to say the least. I'm learning more and more about my 74 as I check these posts. I boought my 260 because the PO couldn't get it started when it died on the hiway. The guy who got it from him couldn't get it running either. As stated, "the red headed stepchild" seems to be giving a few of us fits. I plan on using an 1 wire GM alt, aftermarket elect fuel pump, and a volt gague. If it still doesn't work, then I'll tear everything out and wire it street rod style. Thanks for all the info fellas.

[Ed260Z]

A little update on this swap. I have a current draw in the system. I think it's with the voltmeter since when I disconnected it there was no problem. I'm going to connect the meter to a new source, and see if that will fix it. Now it's running through the shunt.

[Ed260Z]

Well there is still a drain in the system, and after more checking it's something to do with the connections I made. I'm going to reconnect the #2&5 wires together and see if that stops it.

[Ed260Z]

The 2&5 wires need to be connected, and not the 2&3. I had connected them before because I got a lot of fluctuation on the gauge when I put on the accessories. This doesn't happen now so it must have been a bad Alt. (Which I changed in the middle of the swap, because I could)

[petem78z]

Ed you stated that you connected the 2&5 and not the 2&3 I read that the 1&5 need to connected. So did you just eliminated both the 1&5 and the 2&3 and only have connected the 2&5?

 

The 260s are a nightmare for wiring we installed a 82 engine and did the wiring as stated at Atlanticz but the problem is that sometimes the car will turn over but will not start, wait a few minutes and then it will start. In order to get the electric fuel pump I had power to one of the black and white wire to one of the relays so I jumped it over to the other and the pump works. Have you eliminated the interlock? I'm thinking that, that could also have an effect on the non starting?!

[TrumpetRhapsody]

Bumping this instead of starting a new thread.

 

Additional info about this, though not as helpful. Need spotfitz's writeup.

 

 

 

Based off of the info given from Atlanticz about the way the alternator charging system works, i've bypassed my 260z voltage regulator as follows:

 

Body Harness:

White to Yellow

Black/white to White/black

 

This gives constant 12v to the yellow, and switched 12v to the Black/white.

 

 

 

Not sure if it's working yet. I ran the ZX alternator with my external regulator for awhile, probably burned something up. We'll see if it charges, but my Amp gauge doesn't seem to think so. (will swap for a voltmeter soon, hush!)

[TrumpetRhapsody]

The ZX alternator was toast. Swapped to a 240sx alternator and had nice STABLE voltage for a week. 3 days ago on the way to school, the alternator put out a constant 17v pegging the ampmeter, and the alternator smelled hot when I stopped and checked it. Started the car back up and it was back to normal. It worked for three days till just now I had a sudden 17v spike that blew the 2amp Megasquirt fuse. Swapped fuses, but now I'm getting nothing from the alternator. Going to autozone tomorrow to test it.

 

[bjhines]

^^^^ you have bad wiring or connectors.

 

The voltage sensing wire must be solidly connected in order for the voltage regulator to work properly. A fault here would cause the votage to increase a limited amount. 17 volts is generally the internal limit for these devices. That would explain one problem.

As far as the alternator "blowing", I dunno. It could be tied to the VS problem. It could also be the result of arcing connections freaking out the semicinductor devices and causing damage. If your VS wire is faulty then there are likely other faults as well.

 

Alternator wiring is very improtant. They are often low in the vehicle and prone to fouling and heat damage. Make sure your wiring is in order and these problems will go away.

[TrumpetRhapsody]

I'll check my connections again, but I previously confirmed with a multitester that I have the "S" and "L" connections hooked up properly. Straight 12v to the "S", and switched 12v to the "L".

 

I guess it could be intermittent connections, but my connectors seemed pretty solid. I suppose I could run a new constant 12v wire for the "S" wire, so I'm not relying on my bypassed internal voltage regulator wiring.

 

I'm hoping it's just bad luck with the 240sx alternator. I think I may pick up a reman ZX alternator from autozone tomorrow. At least it'll be in new condition, and have a warranty.

 

 

I may see about going ahead with bypassing the shunt, and installing the 280z voltmeter as well. I doubt that's the problem, but it couldn't hurt.

[TrumpetRhapsody]

240sx alternator was indeed dead, failed on all counts.

 

Bought a new 280zx alternator for $50, so not too bad seeing as the warranty will provide some peace of mind. Voltage is now stable at 14v, MS registering a .4v spread. Hopefully this one will last longer than a week

[HLS30-08077]

240sx alternator was indeed dead, failed on all counts.

 

Bought a new 280zx alternator for $50, so not too bad seeing as the warranty will provide some peace of mind. Voltage is now stable at 14v, MS registering a .4v spread. Hopefully this one will last longer than a week

 

 

OK, it's been almost 2 months, what's the verdict so far??

 

Please update and advise,

Dave

2/74' 260Z

[TrumpetRhapsody]

Whoop, sorry, meant to update.

 

It's been going strong ever since, awesome stable voltages in MS, nice strong power from the alternator. I guess I just got a bad SX one. w00t

[TrumpetRhapsody]

After 2 years my Autozone battery gave up the ghost, so I finally decided to upgrade to a voltmeter to keep me from getting stuck away from home again. In the process I re-checked and re-evaluated my external regulator wiring bypass, and expand on the way everyone above was wiring in the voltmeter.

 

I've attached some really bad pictures just to give a general idea. I decided to keep and modify the stock gauge wiring instead of swapping over the ammeter's wiring. Here is how I did the wires at the gauge so that it plugs into the stock harness with no modification:

 

-Voltmeter positive red sleeved black to the connector blue

-Voltmeter negative black spliced into the connector black

-Back-light green/white to the green/white bullet connector in stock harness

-Charge light blue to the connector green

 

Now in the engine bay down at the external voltage regulator connector:

 

-Cut the white thin shunt wire, and connect it to your White/black at the regulator connector

-Connect together the yellow and white regulator connector wires

 

 

It would probably be a good idea to put a diode on the shunt white to white/black wire to stop it from back-feeding, but I haven't done it yet and it's been running fine. This configuration is an easy way to do a minimal amount of harness cutting, but have a functional charge light without running new wires.

 

 

Additional thought: It might be a better idea to connect the voltmeter positive (black with red sleeve) wire to the green connector wire so you only get a voltage reference with the key on. It might not be as accurate as a straight feed to the shunt, but right now my gauge reads all the time, which over a long period of time might have a slight drain on the battery. If i don't drive the car for an extended period I usually unhook the battery anyway, so it's not a big deal for me.

Edited November 16, 2010 by TrumpetRhapsody

[11/73 260Z]

I'm about to under go this project but want to be clear on the alternator I should buy. I'd like to get a 90 amp that works on the same brackets as my factory 11/73 260Z has. I saw mention of a Maxima and a 240sx. Can someone elaborate on the year and will the same alt belt work on these? I know my questions may be a little too specific but I want to have everything in order before I dive in.

Thanks,

Chris