Revision as of 04:33, 26 July 2011

Our Datsun B110 used -- as with most 1964-1974 cars -- an Alternator with external Voltage regulator.

1 Overview
2 How the Alternator Dash Light Works
3 Automatic Choke Relay
- 3.1 B310 Choke Wiring
4 Alternator Upgrade

Overview

Alternator Connections

terminal	Color	Logical Connections
A (Alternator)	WR or W	* To Battery + terminal through the Fusible Link * To Regulator "A" terminal (W wire)
F (Field)	WB	* To Regulator "F" terminal
N (neutral point)	Y	* To Regulator "N" terminal * To electric choke relay Y wire
E (Earth/ground)	B	* To body ground * To Regulator "E" terminal

Regulator Connections

terminal	Color	Logical Connections
A (Alternator)	W	* To Alternator "A" terminal (WR or W)
F (Field)	WB	* To Alternator "F" terminal
N (nuetral point)	Y	* To Alternator "N" terminal * To electric choke relay Y wire
E (Earth)	B	* To body ground * To Alternator "E" terminal
IG (ignition)	WL (72: W?)	* To fuse box "M" terminal (does not go through IGN switch)
L (Light)	WR	* To dash light "IGN" ('72, '73) or "CHG" (1971)

How the Alternator Dash Light Works

The dash lamp is connected to IGN +. The other side goes to the "L" terminal of the external regulator.

When the alternator is not putting out current, the "L" terminal is at '-' voltage, so the dash light turns on
Once the alternator starts putting out current, the "L" terminal is at + voltage, so the light turns off (both sides of the light are at +)

This also is connected to the F (field) connection of the alternator, so it "turns on" the alternator. It is the switched 12V (through the lamp) that kick starts the alternator fields.

WARNING: This mean that if the dash lamp 
is burned out, the alternator does not work

Automatic Choke Relay

On Datsuns equipped with an electric Automatic Choke, a relay is used so that the choke heater is activated only when the engine is running. B110 uses a normally open relay -- the choke is powered all the time when IGN is on, but when the engine is not running the relay disconnects the choke power.

As soon as the choke heater gets hot, it comes off the choke. If your engine is cold, you won't be able to restart it. For example, if you listen to the radio for a couple of minutes before starting the engine, and mistakenly put it to IGN, then the car won't start on a cold day. To prevent this scenario, the relay only powers the choke when the engine is running. The alternator provides a signal when the engine is running. It is the Neutral Sense wire (N wire). This is a weak signal so a relay is used.

The choke is powered by a separate 10A fuse, which also supplies the Anti-Dieseling Valve.

The relay is connected to Ground on one side, and to the N wire on the other.

Black: ground
L (Blue): to 10A fuse then to IGN FUSE BOX (always hot)
Red: choke
Yellow: N wire of alternator & regulator (turns on relay)

B310 Choke Wiring

B310 uses a normally open relay. Turning on the ignition switch activates the relay, pulling power away from the choke heater. When the engine starts, the relay turns off, resuming flow of power to the choke.

NA B310 uses internally-regulated Hitachi LR Alternator with L terminal in place of N terminal.

The relay controls

Normally closed (doesn't work when engine OFF):
- Choke Heater
- Fan relay
- Warm-up Relay 1
Normally open:
- Brake lamps

Also see: Choke Operation wiring section

Alternator Upgrade

Many different Datsun alternators and alternators from other makes can easily be fitted to the Datsun 1200.

See main article: Alternator Upgrades

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Alternator Wiring