From: Steve Golik
Date: Sun, 22 Dec 1996 20:43:35 -0500
Subject: <240> 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 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. 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, you will probably 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.
Steve Golik
Smoky Mountain Z Car Club
Knoxville TN
1971 240Z
1974 260Z (3.1 liter)
1979 810
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