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Revision as of 11:00, 30 April 2016

The Hitachi LR Alternator series uses the same T-connector but wiring is different. If you use this newer type in an early Datsun 1200 the external voltage regulator must be disconnected a minor wiring changes made.

1 Overview
2 Fitting To Early Datsuns
- 2.1 Wiring Explanation
3 Automatic Choke
- 3.1 Original Wiring Comparo
- 3.2 Compatibility
4 Troubleshooting
- 4.1 Engine Won't Shut Off
- 4.2 Regulator Still Plugged In

Overview

JAPAN Datsun 1200 starting in 1981 uses an internally-regulated Hitachi LR-135 alternator. North America Datsun starting 1978 also used 35A, 50A or 60A versions. All are wired the same way.

L - Lamp (stem of T) -> To dash 'CHG' Lamp
S - Sense (head of T) -> to BAT+ via Fusible Link

Here is the factory wiring diagram portion:

Notice the I.C Alternator T-connector head is connected to BAT+ line(unswitched battery voltage). 1978 B210 is the same but wire colors differ.

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1979-1982 B310 North America colors
B - Black wire. Earth/Ground
W - thick White wire. BAT+ via Fusible Link
W - thin White wire in T-connector head. BAT+ via Fusible Link
WR - White/Red in T-connector stem. To dash 'CHG' Lamp

Notice that the I.C Alternator T-connector head is connected to A/BAT terminal (unswitched battery voltage). The splice occurs in the wiring harness.

1978 B210 Colors
B - Black wire. Earth/Ground
WR - White/Red. BAT+ via Fusible Link
Y - Yellow. T-connector head. BAT+
WB - White/Red. T-connector stem. To dash 'CHARGE' Lamp

Fitting To Early Datsuns

If you install an LR alternator with internal-regulator on a 1200 or other Datsun with FN type alternator:

disconnect the voltage regulator
in the regulator connector of the engine harness, connect WB wire to WR wire

WR <--> WB
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Logically, you are connecting the "L" (Lamp) of new alternator to "L" (Lamp) of the wiring harness which is connected to the IGN switch. Be sure to use the original Datsun 1200 wiring harnesses as the "L" wire color WR is a switched source in the harness. Only one jumper wire is needed.

If your Datsun was factory fitted with auto-choke, also jump these wires so that the auto choke relay operates:
Jump W to Y wires

wiring diagram:
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Store-bought version ($30) of jumper wire

You can buy one mail-order from Bprojects. Endo will take care of you, send an email to Bprojects.

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Price: 5,250yen (about $52 USD)

Wiring Explanation

CAUTION: if you jump W to B it will spark, begin to melt and then blow the Fusible Link. Possibly too with other wire combos too depending on if the key is on or off. In any case it should not cause a fire if the Fuses and Fusible Link are all in place. Older Datsun 510 & 521 may not use a Fusible Link, so be sure to connect the right wires.

Voltage Regulator connector
* White: battery feed
* Yellow: Neutral (of original FN alternator)
* White/Red: Lamp (dash CHG or IGN light)
* White/Black: Field (of original FN alternator)

In the conversion:

Yellow goes to S terminal of LS alternator, so jumper connects Sense to battery
WB goes to L terminal of LS alternator, so jumper connects Lamp to dash lamp

You can double-check all this with a voltmeter.

The original 35A alternator should have FN terminals

The Internally Regulated alternator should have LS terminals (but same T-connector as FN types)

Automatic Choke

NOTE: If your Datsun was factory-equipped with Automatic Choke, a second jumper is needed at the choke relay connector.

Original Wiring Comparo

With a wiring harness for LT-series alternator the choke relay is Voltage switched (voltage provided by Alternator).

Alternator output will power the relay, activating the choke heater. See Electric Choke Wiring.

With a wiring harness for LR-series alternator, the choke relay is Ground/Earth switched (ground provided by Alternator).

Alternator will ground the relay, de-activating the choke heater.

FN: relay with normally on connection to choke
    relay clicks when engine starts running
LS: relay with normally off connection to choke
    relay clicks when you turn IGN on

Compatibility

The Choke Relay is wired oppositely different on LT-series and LR-series applications. The respective wiring harnesses and relays match. New harness uses 6-pin relay. Old harness uses 4-pin relay.

When swapping newer LS-type alternator into older FN-type vehicle, swap N and L lines with a jumper wire. Then the lamp and choke circuits will work as designed.

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Troubleshooting

1. Check the Voltage at the alternator. Between the BAT terminal and the E terminal (earth/ground) there should be the same V as at the battery. If not, you got a wiring problem.

2. The S terminal should be 12V hot when key is turned to IGN

NOTE: on the B310 with this, S is hot all the time
either way will work

3. The L terminal (Lamp) should be:

0V when key is turned OFF
12V (more or less) when key is turnd ON

Because the L terminal is the exciter, if your CHG lamp is burned out, the Hitachi LR won't charge.

Engine Won't Shut Off

If wired incorrectly, the engine will keep running when you turn the key off.

Regulator Still Plugged In

The FN wiring is different from LS wiring. So if you leave the external regulator still plugged in, the wires are incorrect.

It won't cause overcharging, since the LR is internally regulated.

L-S
Lamp: stem of Tee
Sense: head of Tee

F-N
Field: stem of Tee
Neutral: head of Tee

If the external regulator is left plugged in:

the Neutral line of regulator will be connected to the Sense terminal
the Field output of regulator will be connected to the Lamp input/output terminal

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IR Alternator Conversion Wiring