240Z VR Adapter Plug Upgrade

[benny]

Hey Guys,

 

Been searching around trying to find the wiring diagram for the VR plug adapter when upgrade to an internal VR Alternator. Can someone please post up what they did!!

 

Ben

[Zedman240®]

Courtesy from Classic Z car (I think!) apologies if not...

Instead of another plug to create the loop plug, I just made a small loop of wire with spade connectors..

 

 

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.

 

4. Connect the black with a white stripe wire to the white with black stripe wire. This connects the "L" terminal to a switched 12V.

 

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.

 

SPECIAL NOTE:

 

I had this problem and thought I'd share the solution. Many thanks to Ken Osman and Steve Golik who provided the solution:

 

When an internally regulated alternator is put into an early Z and the external regulator is removed, you often have the problem that the car will not shut off when the key is turned off.

 

You have to put a diode in series on the wire that goes to the "L" terminal on the back of the alternator. The "L" terminal is the bottom contact on the "T" shaped connector.

 

You have to connect the cathode of the diode (identified by a stripe on that end of the diode) to the "L" terminal and the anode (other end of the diode) to the wire that previously went to the "L" terminal. In my case (71 240Z) this was a white with black stripe wire. This prevents the "L" terminal current from feeding back into the ignition circuit when the key is turned off.

 

The diode I used was a 1N5402, other people have used a 1N5400 or a 1N5062. Easy fix to a vexing problem.

 

Side note: when I fixed this I connected the Yellow wire in the harness which leads to the alt to the "S" terminal (top of the "T" connector) on the alt - PO had spliced white/black wire into both the "L" and "S" terminals - my under hood light started working. WHOOOHOOOO!

 

71 L28 now shuts off with the key!

[sexual_sushi]

Hi Benny, I just installed a plug a week or so ago. Let me check on the weekend but from memory the plug goes something like this:

 

  | - -0- |

|  -=- -  |

 

With the 0 being the diode connecting between those 2 pins and the = just a connection between those 2 pins. It probably doesn't make much sense and I could have the diagram all wrong so I'll check on the weekend and post a pic.

 

I believe you can buy the plug from tandy or jaycar as well as the diode. Once you have connected the 2 bottom pins and connected the diode you can fill the plug with a 2 part resin to seal it up into a solid little unit. If I can get the parts on the weekend I'll make a batch up to sell to anyone who wants it for something around $15 although it's probably about $6 worth of parts (plus resin) if you want to do it yourself.

 

The benefit of the plug is that you don't have to hack up the wires and therefore is backwards compatible. If you aren;t worried about this then you can just connect your wires and put in a diode.