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[Datsun 1200 encyclopedia]

EGI Wiring

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Categories: Fuel System | Fuel Injection

Wiring for the Datsun A14/A15 EFI (EGI) system.


Contents

Overview

Wiring here is based on Datsun S110 (Silvia/Gazelle/240RS), specifically the 1981 USA "200SX" version. See 200SX EFI.

The simplified "4-wire" setup, which assumes you are using a factory wiring harness cut out of a donor car, is:

  • IGN
  • START
  • GROUND/EARTH
  • FUEL PUMP


Engine Harness

21852.jpgAlbum click to view
Engine harness

  • Injectors
  • Air Regulator (air bypass system -- for idle speed)
  • EGR/VVT vacuum-cut switch (can be disconnected)
  • Throttle Sensor (Throttle position sensor)


ECU Wiring

22612-N7801 to 0681 (no O2)
22612-N8500 from 0781 (O2 sensor)
Wires from ECU to engine compartment
OUTPUTS
* Injector outputs (4)

Wires from engine compartment to passenger compartment
INPUTS
* Power (from EFI relay)
* coil negative (tach sense)
* air flow meter
* air temp sensor (in flow meter)
* throttle valve sensor
* START wire for ignition switch (to indicate when to do cold-start enrichment)
* water temp sensor (on underside of intake manifold)
* O2 sensor (not used on early B310)

EFI Relay

Needed: One relay, one Fusible Link, 20 gauge Power & Ground wires

There is a dedicated Fusible Link for the ECU
26065.jpgAlbum click to view

21854.jpgAlbum click to view
25230-C9900 RELAY ASSY [or 25230-C9907]
* SWITCH: 
  * C: BW wire from IGN switch
  * E: B ground/earth
* D SOURCE: from Brown fusible link to Light Green/white
* B OUTPUT: LgR to Red wire to ECU #207

200SX factory wiring diagram
21855.jpgAlbum click to view

B310 A14E wiring diagram
034aRelayECU_1.jpg full | original

B310 ECU PIN
27 POWER
15 EARTH

Fuel Pump Wiring

Pump has 2 wires
* B: earth/ground
* LgR (Light Green with Red stripe): pump power

S110 uses 3 relays: FUEL PUMP RELAY 1, FUEL PUMP RELAY 2, FUEL PUMP RELAY 3. The multiple relays are for safety. Relay takes inputs from Alternator, ECU, and Oil pressure switch. Pump will shut off if engine dies, because Oil and Charge will stop working, the relays shut the pump off. This is important for safety in a crash.

Fuel Pump Relays

At the minumum to protect the wiring, you need one relay for the fuel pump. It draws over 5 amps, so you don't want to run it directly through the IGN switch at the risk of burning out the switch contacts or overloading the existing small IGN wiring.

Although you could use the minimum one relay, for safety the Datsun factory system uses a chained system of three relays.

Nissan 5-blade relay
* 25230-C9900/25230-C9907 RELAY-FUEL PUMP JIDECO 
* 25230-C9905 RELAY-FUEL PUMP NILES 

Fuel Pump Relay 1

Pump On/Off: this relay engergizes the Fuel Pump and Air Regulator, but Relay 2 can open the circuit.

* SWITCH: 
  * C: (Lg) from Fuel Pump Relay 2 OUTPUT (Lg)
  * E: Earth/ground
* D SOURCE: BW from IGN switch
* B OUTPUT: LgR 
  * to Air Regulator LgR
  * to Fuel Pump LgR

21854.jpgAlbum click to view

Fuel Pump Relay 2

Pump Power: This relay is wired NORMALLY CONNECTED (i.e. when off). It passes on to Relay 1, but when Relay 3 is on it disconnects.

* SWITCH OFF: 
  * C: L from ACC L FUSE 15A
  * E: (switched ground) LW from Relay 3 OUTPUT (LW)
* D SOURCE: BW from IGN switch
* A OUTPUT NORMALLY CONNECTED: Lg to Relay 1 SWITCH(Lg)

Fuel Pump Relay 3

Pump Cutout: This disconnects the Pump Feed relay in certain scenarios.

* SWITCH: 
  * C: BW from IGN switch
  * E: WR to DIODE to Alternator WR
* D SOURCE: YW to GROUND/EARTH via Oil Pressure Switch
* B OUTPUT: LW to Relay 2 SWITCH (LW)

200SX Oil Pressure Switch is a dual-wire type because 200SX has an oil pressure gauge, but we only need the typical sensor used on all A-series engines. If you want to use a Oil Pressure Gauge, you can fit this sensor.

25070-80W0 DUAL OUPUT
* On/off pressure switch for OIL light & fuel pump relay
* Resistor sensor for gauge

Injector Wiring

How the injectors are wired depends on the ECU you use. The following is information on Nissan ECUs. If using Motec, Haltech, etc. see their instructions.

Here's the actual schematic for Dropping Resistor wiring from the 1978 A14E Service Manual. It shows a 5-pin resistor pack.
EGI_harness_.jpg EGI Harness

1981 S110 USA (Z20 engine) uses the same 5-wire Dropping Resistor
200X_EFI_injectors.jpg

  • Both systems provide 12V to the resistor pack common pin.
  • The injectors are grounded via the four ECU injector pins.
  • B310 (A14E) 12V is supplied via dedicated Fusible Link and ECU/ECCS relay
  • S110 (Z20E) 12V is supplied via dedicated Fusible Link (always hot)

1978 A14E
034a_relayINJECTORS.jpg

Dropping Resistor

Fuel injector dropping resistor: 2.35 ohms resistance.

20100829190547DSC00753x.jpg 

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