Diode?
 

Hey guys and gals,
I am looking for the location of a diode that connects on the black/white wire running into the fuel pump relay. It shows it on my wiring schematic but I have had no luck in locating it. Thanks in advance. Steve

Diode????
 

You still working on this? I don't know of any diode? What year is your SVX.

Diode??
 

Is the diode in the ECU?

Diode
 

I am not sure if it is located in the ECU, but from the wiring diagram it appears to be a stand alone diode. My car is a 92, and yes, it is still not running. Looks good though. :D Steve

Diode or Relay?
 

Please elaborate on why you are checking your diode. Are you not getting power from your ECU to turn on your fuel pump? Are you checking the relay power quickly after you are turning on the key? Because the power to the pump shuts down shortly after you turn the key if the engine does not turn on. Do you mean relay instead of diode? Last time I spoke with you, I thought you determined that jumpering the relay you got power to the pump. Now I'm assuming you checked the relay and the relay works, you are not getting a signal from the ECU. Make sure the relay is not burned. If it is not, I would take it to a subaru dealer and tell them what you have already done on the car. If its a matter of towing costs, you could jumper the relay and see if it runs, but I don't recommend it unless you are flat broke. I think you might have an ECU problem.

The manual for right hand driving position cars shows it as under/behind the instrument panel (RH side), among the the usual motor manufactures birds nest of confusingly mounted stuff. It is incorporated so that the single pole on the ignition switch does not cause a sneak circuit to the main relay and could well have been an afterthought.

N.B. ----- This diode is not involved in voltage supply to the fuel pump. I gather you have thought it could be, because of the way it is associated within the wiring diagram.

There should be 12 -13 volts at the fuel pump relay black white wire, connection B51 pin 1 and ground, at all times as this goes direct to the battery via fuse no. 16.

The Green black wire goes to the MPFI control unit, where it will be grounded when required by the control circuitry, so as to operate the relay and hence the fuel pump. As has been pointed out this will be on/off after the ignition is turned on.

The fuel pump becomes energised as required via the relay contact and this goes direct from the battery, via the yellow wire and fuse SFB- 2. There should at all time be 12 - 23 Volts from this wire to ground.

The relay output to the fuel pump circuitry is via the blue wire and again this will be on/off with ignition, as above. Again check for 12 - 13 volts to ground.

Check all the above, which involves the supply circuitry. If all is OK, you can move on to the fuel pump. Go slowly, carefully bit by bit and logically.

Use a simple 12 volt test lamp, rather than a voltmeter. A lamp draws a reasonable current and should light up bright. Check direct against the battery by way of a comparison. A high resistance meter draws a minute current and will not show up a low resistance in the supply line.