Electric Choke Wiring

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Revision as of 08:41, 20 November 2012

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.

Simple Wiring

For cars without a choke relay, you can simply hook the choke up to the Hot side of the ballast resistor or any other IGN switched wire. The downside is when you can't get the engine started right away, the choke heats up while you are trying - on cold days you may never get it started. So using the alternator output and a relay is a better idea.

Overview

Datsuns originally equipped with Automatic Choke and Alternator with external Voltage Regulator use a normally unconnected Choke Relay -- the choke is only powered when the engine is running and the alternator is charging. It ties into the CHG Lamp: when lamp goes out, choke relay powers the choke heater.

The relay is designed to solve this problem: if you listen to the radio for a couple of minutes before starting the engine, and mistakenly put it to IGN, then the has already heated up and 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. The signal is from the Neutral Sense wire (N wire), which supplies charging voltage

B110 Choke Wiring

The 1972-1973 auto choke is powered by a separate 10A fuse. On a 1973 this also supplies the Anti-diesel valve.

The switched side of the relay connects the IGN wire to the choke wire.

L (Blue): to 10A fuse then to IGN switch
R (Red): to choke

The relay coil is activated by these two wires:

Black: ground
Yellow: N wire of alternator (turns on relay)

The factory 1200 auto choke setup (1972 & 1973 USA models) uses a relay:

• Red - to choke
• Yellow - to "N" wire of regulator/alternator
• Blue (L) - to Fuse 10A in fuse box IGN side

  (also to Anti-diesel valve on 1973 carburetor)

• Black - to ground/earth

Location of Choke relay: To left of radiator

Part Numbers

25235-P0101 ASSY-RELAY,HEATER,AUTO CHOKE $68.68
superseded 25235-P0100 ASSY-RELAY,HEATER,AUTO CHOKE 0671- USA
* Same as Datsun 510
* Same as Datsun 521 pickup
* Same as 1974 Datsun 710 
* 25235-P0110 NILES brand
240Z Pump Relay
* F.D Furuhashi/Elecman SRK12-1
* Beck/Arnley 203-0015

4-pin spade connectors, Normally Open

Alternatives

• The B310 relay is much cheaper, but has six connectors. 2 would remain unused if you used that switch which has a different connector. 25230-89915. This assumes that is has NO and NC connections. Use the NO connections to replace a B110 relay (not confirmed if this will work)
• B210 relay is similar, but uses B210 style (round) connector 25235-H6200/B5235-H6200
• Generic 12V normally-open Relay could be used

B210 Choke Wiring

B210 with IR (1978) uses 6 connections wired oppositely to prior type (not shown)

1974 B210 North America uses 4-pin round connector.

Below: 1976 North America B210 uses 6-pin relay (one pin is Not Connected) with semi-rectangular connector.

photo

Choke Wiring is logically same as B110, except that the Brake indicator lamps are also controlled by the dual-pupose relay.

B310 Choke Wiring

B310 uses a combo relay, six connectors with both normally open and normally closed pairs. 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 (de-activated when relay is ON):
  • Choke Heater
  • Fan relay
  • Warm-up Relay 1
• Normally Open (activated when relay is ON:
  • Brake lamps

Locations

• The choke relay is mounted in the relay box on the rigth side strut tower.
• The check test connector is located under the dash near the fuse box.

25230-89915 RELAY ASSY-AUTO CHOKE $24.57 USD
B5230-89985
240Z ignition relay

6-pin spade connectors, Normally Connected + Normally Open