How to Convert 240Z to Internally Regulated Alternator

[Bambikiller240]

I've never done this modification so be aware that I cannot be responsible for the outcome of your attempts to follow this procedure.

I'm not repsonsible for anything! Yeah, That should cover it!

Carl

(bambikiller240)

This information is from an article prepared by Steve Golik of the Smoky Mountain Z Car Club. I copied it from ZHome.com and from the archives at ZCAR.com

The Purpose of this page is to give the reader an understanding of how your present externally regulated alternator, can be replaced with a newer model, internally regulated alternator .

Converting to an Internally Regulated Alternator

Question: I would like to know if anyone has converted from the external regulated alternator to an internal. What wiring did you change?

Answer: First a little background: The 60 amp internal regulator alternator was used on the '78 280Z and then the non-turbo 280ZX. I have also seen it on the '78-'85 810/Maxima and the '81-'85 720 pickup trucks. It is marked "LR160" on the case. There was also a 70 amp version (marked LR170) that was used on the 280ZX turbo's.

[Note: It looks like the '84-'86 non-turbo 300ZX 70 amp alternator could be used as well, but the wiring connectors are different, so get (i.e., cut it off) the corresponding engine harness connectors as well if you get one of these alternators. I'll write this up this conversion later.]

Because I don't like to give instructions without some explanation of what you are doing (it makes troubleshooting easier), I will start by describing the internally regulated alternator's electrical connections:

1. An "L" connection which goes to a "switched" 12V supply. By this I mean a 12V source that is active only when the ignition switch is in the ON position. I use the mnemonic "L" for "lamp", the alternator warning lamp (if used) is in series with this connection. This terminal also supplies the "excitation" current to the alternator field winding at engine turn on, allowing the alternator to begin producing voltage as the engine is ramping up to idle speed. Once the alternator rotor is turning fast enough, it generates it's own supply for the field winding and the current in the "L" connection stops flowing. The warning lamp (if used) goes out.

2. An "S" connection which goes as close to the positive terminal of the battery as physically possible. The "S" connection "senses" the battery voltage and this is the voltage that the regulator is tying to control. This connection has a high impedance, so it only draws only micro amps from the battery, so it can be left connected without fear of battery discharging.

The "L" and "S" connections are in the plug connector on the rear of the alternator that looks like the capital letter "T". The top of the "T" is the "S", and the other part of the "T" is the "L".

SEE IMAGE FILE AT BOTTOM OF ARTICLE FOR DIAGRAM OF PLUG

3. An "A" terminal, which is the output of the alternator, which also is connected to the positive terminal of the battery. This connector carries the charging current. Because of the high currents this wire must carry, it is a low gauge wire, which means it has a large cross sectional area. For safety reasons, a fusible link should be in series with this connector. The "A" terminal is the insulated threaded stud on the rear of the alternator.

Of course, someone may ask: "Why do you need two separate (the "S" and the "A") connections between the battery and alternator?". It is because of the fact that even large wires have some resistance, and therefore there will be a voltage drop between the alternator and the battery when the battery is being charged. If the regulator sensed the alternator output (which is higher in voltage) and not the battery terminal, the result would be undercharging of the battery. Now there are alternators which work this way, but they need a fairly large diameter charging wire to reduce the voltage drop. The separate "S" connection is a much better method of regulation.

4. There is a "P" terminal on the 280ZX turbo alternator (but I have also seen it on a few of the non-turbo 280ZX alternators). There is not a corresponding connector on the engine harness to mate with the "P" terminal, even on the turbo 280ZX's. So, the "P" terminal is not used/needed.

5. Finally, there is a ground connection on the alternator, although the case is a pretty good ground connection to the engine block.

Now, the following procedure only applies to the 240Z. The 260Z has electrical connections between the regulator and the interlock module and the electric fuel pump, so it's more difficult to convert to an internally regulated alternator, but I have a procedure for it as well. Please email me directly if anyone is interested. I have not looked into converting a 280Z, but I would think that it would be possible as well.

1. Disconnect the battery.

2. Unplug the external regulator and note the color code of the wires that are on the regulator connector of the engine wiring harness. You will be connecting some of these wires together, so get another plug from a junked regulator or cut the one off your old regulator. Now the wire colors I will be referring to are on the regulator connector of the engine wiring harness. This is because although the regulator wire colors match the engine harness with the stock regulator, I've noticed that some aftermarket regulators have a different wire color code.

3. Connect the white wire to the yellow wire. This connects the battery to the "S" input.

4A. Because of a minor wiring difference between late and early 240Z's, you may need to add a diode so the car will shut off after it is started. An electronic component called a diode can be used to prevent this. Obtain a 1N5062 (or equivalent) from your local electronics supply company. A diode has two leads, an anode lead and a cathode lead. The cathode lead is identified by a band near that lead.

4B. Connect the anode of the diode to the black with a white stripe wire and the cathode of the diode to the white with black stripe wire. This connects the "L" terminal to a switched 12V supply through the diode preventing reverse current from flowing.

5. Disconnect and unbolt your old alternator. Bolt up the new alternator. Depending on what particular internally regulated alternator you use (I've seen different pulley sizes), you might need a different length belt.

6. At the alternator, connect the white with red stripe wire of the engine wiring harness to the threaded stud (the "A" terminal) on the alternator. This connection provides the charging current for the battery. Connect the black ground wire to the alternator. Don't forget to include any bypass, or filter capacitor. Plug the two-pin "T" connector into the alternator.

7. Re-connect the battery and start the engine. With a good digital voltmeter measure the voltage directly across the battery terminals. This is the charging voltage. It should be 14.7V +/- 0.3V, but this voltage is a function of the ambient temperature and the state of charge of the battery. If the voltage reading is not correct, then re-check your wiring. More than 15.0V indicates that the "S" connection may not be connected correctly.

[Dr. Tom]

My name is Thomas, I have a 71 240 z I want to use the ZX 70 amp alternator upgrade. I need to buy the plug for the back of the alternator offered by arne berklund? I cant E-mail him or call him no way to contact him. Can you help me to locate him to buy this plug adapter.

[Jeff G 78]

Arne posts here all the time. Do a search for 'arne'.

[BRE-240Z]

You want to talk to Dave Irwin, actually. Arne designed the plug, I believe, but Dave sells it. You will find contact info here, at the bottom of the page:

http://1971.240z.home.comcast.net/extras/alt-adapt.html

[Arne]

Thanks, Brian. 100% correct. I do host the info page listed above on my website, but Dave is the man.

[DeesZ]

I do recommend this conversion. (Did it on my '72).

Arne and Dave have made this a low-cost painless task that has great rewards. My next mod will be Dave's conversion wiring for headlamps.

[240Adam]

Dave is a friend of mine and I have his phone # if you want it PM me.

[Carl Beck]

For some reason, this did not seem to work completely on my 73. If I turn the key "off" the engine stops, but if when turning the key I pass "off" and continue to "acc" or "lock" the engine keeps running... So I just turn the key "off" - wait there a second, then continue to rotate the key to the "lock" position. The car is not pure stock.... but pretty close as far as the car's wiring harness goes...

FWIW,

Carl B.

[Arne]

Carl, I'm confused. On all of my Z's (one Series 1 and two Series 2s), from 'run' the next position is 'acc' and then 'off'. So your description of pausing at 'off' before continuing to 'acc' or 'lock' doesn't make sense.

Or are the ignition switches in a '73 that much different? I thought the late '71-73 were all the same.

[ktm]

I bought one of these adapters and it worked great.....until I somehow completely fried the yellow battery sense wire coming from the alternator. I mean I FRIED it, as in NO insulation left between the alternator and the battery sense wire. I also fried the adapter.

I finally cut out the old voltage regulator female plug and just connected the wires. I installed the diode using mechanical butt splices. The diode fit perfectly inside the two halves. I then heat shrinked the whole wire.

The plug is a very easy and elegant solution. However, if you want a 'clean' look and eliminate the plug altogether, you will have to do the splicing by hand.

[Arne]

One of my main goals in designing the plug was that the process be 100% bolt-on, no wiring mods needed, and the whole affair be 100% reversible in case you ever wish to go back to stock. If that's not important, certainly splicing the wires will work fine. Nothing magic about the plug.

[74260z4me]

Hi Arne my name is Stacy I have a early 1974 260z and I want to upgrade to a 280zx alt. which I do have I keep finding info for a 280z but not for the 260z. Any help would be appreciated my home e-mail is candss4@yahoo.com if possible I can call you all I need is a contact number. Thanks in advance Stacy