Alternator Swap (Putting an '82 280ZX alternator in a '77 280Z )
- The original '77 280z's build has an external mechanical voltage regulator that is unreliable and unstable with age. It is actually based upon elements that open and close many times each second due to heating and cooling. The principal is not much different than the overheat protection devices commonly used in your toaster and hairdryer. It also requires frequent adjustments of gaps much like spark plugs.. The newer ZX alternator incorporates a built in solid-state voltage regulator that requires no maintenance and is more stable.
- The wiring between the alternator and voltage regulator typically is problematic. On the ZX unit, the regulator is inside the alternator body so there are no interconnections to worry about.
- The Z alternator is rated at 50A. The ZX alternator is rated at 60A (It is physically bigger)
- The upgrade is pretty much bolt and go. Two wires need to be jumpered or spliced and that is it!
- The ZX unit is newer, readily available in junk yards and inexpensive.
- The ZX unit is rock solid an the DC voltage is 14.45V at all RPMS (as measured on mine).
- No more wavering Voltage gauge or hunting of the fuel pump.
- This swap worked great in my 77 280z. I assume it will work in 75 & 76 280Z's. I do not know about 240 or 260 Z's.
Compatible Donor Alternators:
- All 280ZX units. Turbos are 70Amp and N/A are 60Amp. '78 Z units also work and are 60Aamp.
- Other Nissan units should work but size or wiring or pulleys may require mods to work (double check your potential source against pics of the stock unit below)
Big Thanks to Z-Creations for info on how to do this swap! Click Here.
ZX alternator on left, Z alternator on right.
Note that all three needed connectors are the same:
- E (Black Wire and Condenser) This connection is Earth or Ground
- BAT (White wire with Red Stripe and other end of condenser wire) This connection is +12V output
- F&N (T connector)
N (Yellow) (on the early alt becomes the Sense signal on the newer alternator (the alternator "senses" the voltage on this wire and attempts to maintain it at 14.45V.
F (white with black stripe) is the Field signal on the early alt that becomes the L lamp signal on the newer alternator.
From the top. The ZX on the left is clearly bigger. It is rated at 60A compared to the Z's 50A
Pulleys seemed to be the same but ZX fan on left is bigger
Disconnect - Neg battery terminal (note I repositioned my battery so that the - neg side is near the firewall).
Here is a pic of the stock 77 alternator before doing anything (use as a reference if needed)
Here is a another reference pic
FYI Name plate on stock 77 alternator "12V @ 50A"
Disconnect the cables to the alternator
Remove 3 bolts that hold alternator in place. I used a 13mm socket for the top bolt that clamps it to the bracket and a 12mm socket for the two bolts holding it to the engine block.
Here is a pic of an easy way to access the lower front bolt. The rest of the work can be done from the top.
Unclamping the carbon canister and moving it aside takes 30sec to do and helps a lot.
Freshen contacts/connectors on new alternator with sandpaper or scotch pad and contact cleaner (Caig Deoxit above)
You just need to do the BAT, E and "T" contacts. Also do the same with the cable ends in the car.
Install new alternator:
- Bolt it in place with 3 bolts but only turn them to "finger tight"
- Install the fan belt
- Use a long screwdriver or broom handle or similar to pry the alternator away from the engine as shown above. Tighten the top bolt with a ratchet while the fan belt is in tension.
- Check tension by pressing firmly on fan belt. ~ 1/2" deflection is fine.
- Tighten all 3 bolts
- Re-connect wires
Locate Voltage Regulator. It is under the bracket holding the fusible links. A 10mm socket removed the 4 bolts.
Here is the bracket removed. You can see the Voltage Regulator and it's inline connector
Here is a schematic of the ZX alternator. Note the internal voltage regulator.
- BAT (+12V battery) connection (White with red striped)
- E (earth/ground) connection (Black) are the same on both alternators and require no changes.
- S (Sense) connection (Yellow) gets connected to a +12V source
- L (Lamp) connection (White with black stripe) gets connected to a +12source that is active only when the car is cranked by the starter. (You can see the node in the schematic where the L lines get power from the warning lamp when cranking and then from the alternator windings via the 3 clustered diodes when operating)
This is the wiring to the electrical harness connector (as seen on the car when you unplug, remove, smash into bits, tramp on and throw away the external voltage regulator)
Here are the two connections to make: 2 to 3 and 1 to 5.
Connect, solder, heat shrink, insulate and wrap
Double check everything (wires correct and snug, bolts tight, fan belt snug and on correct pulleys, no tools in engine compartment, carbon canister put back and hose put on, correct jumpers at connector)
Connect -neg battery cable briefly (1sec) and make sure there are no sparks or smoke!
If all seems ok, connect -neg battery cable and try starting. Watch for smoke and watch the battery gauge for correct voltage and Red LED functioning.
FYI if you have a '76 280z, the colours are slightly different:
- The white with red striped wire on the 77 is just white on the 76 (still pin 2)
- The blue wire on the 77 is green on the 76 (still pin 6 and unused)
Here are the '76 connections for your convenience
Ok, many people are still confused. Here are the jumper connection details for each year
1975 1976 1977 Connect 1-5
(lamp to windings common)
green&red to white&black blue to white&black blue to white&black Connect 2-3
(+12V to Sense)
white to yellow white to yellow white&red to yellow
'73 240z Connector to VReg (Rectangular)
Great post on www.Zcar.com
Date: May 14, 10:48am
I followed these instructions I found on the net and it worked perfect. Also before you do this, do a search on this site for diode. Sometimes when you convert to an internal regulator, the car will not shutoff when you turn the key to off, this is due to current bleeding through the alternator, a diode must be placed in the circuit to block it
Converting to an internal regulator alternator
I would like to know if anyone has converted from the external regulated alternator to an internal. What wiring did you change?
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". Or
in crude ASCII art:
: ------- : "S"
:.... | ....:
: | :
: | : "L"
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.
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.
Date: Jul 5, 7:08pm
BTW, with regard to the terminal marks on the GM alternator case:
GM/Delco "1" = GM/Delco "R" = Datsun "L" = warning lamp/Switched +12v
GM/Delco "2" = GM/Delco "F" = Datsun "S" = constant +12v current sensor