Main Relay (GND Switched 0V = ON)

[Cable_ties]

Hello

i am using a relay pack ( picture attached ) I/P 3 Main Relay (GND Switched 0V = ON) , Can i join this wire to the Fuel Pump (GND Switched 0V = ON) ? that goes to the megasquirt
or can i just put it to the battery - terminal ? Can someone tell me where to put this wire because it is driving me NUTS .

[RobH]

It looks like the "Main Relay" is intended to provide power to Megasquirt (hook pin OP3 to 2A fuse to Megasquirt +12V in). You do need to wire an unswitched (direct from battery) power source to pin OP6. The third and final thing needed to supply a switched power source to your Megasquirt is a switching ground signal to pin IP3. This means when you turn your ignition on pin IP3 will go from open to Grounded. Not sure if your ignition switch can accommodate this.

This Main Relay then supplies juice to the Fuel Pump Relay. It looks to me like you could wire IP2 to IP3. All that's needed for the Fuel Pump Relay is to hook pin OP4 directly to the + terminal (after a fuse, mine is a 15A) on your Fuel Pump and pin IP1 to the Megasquirt Fuel Pump output (Megasquirt grounds this pin to turn on the relay to supply juice to the Fuel Pump).

Not sure what you'd want to use those other two relays for- Starter and Oxygen Sensor but they're definitely handy to have.

You're gonna want to check thru this to make sure it's right as I'm just scaling thru the diagram quick.

[Cable_ties]

Thanks for the reply
i not using the other two relays, I'm using the board Because it is encased and the original from the car, That is pretty much the same as i have it wired, however the fuel pump is not priming, is there anyway i can check to see if the megasquirt is switching the fuel pump output ?

[RobH]

Megasquirt grounds the output pin for a couple seconds (not sure how long exactly) when it's first turned on. You could pull the relay and check continuity from the pin that the Megasquirt wire goes to and ground. It should be continuous (0 ohms) to ground for the first couple of seconds when the ignition switch is turned over. Of course, if you have a noid light and would prefer that you could hook the ground of the noid light to this terminal and positive to a know 12V source.

I'm sure there are other methods but that's what I'd do.

[Cable_ties]

I went outside with my new multimeter today , i had no volts on ignition live when it is in position II, i change my fuse box and now i have 12v with the ignition on at I/P 2 , like i am suppose too, I also have 12v at I/P 1 with ignition on and no volts at O/P 4 which i think is the wrong way round, i have added a diagram of how the mfu is wired in now, i also tested all the pins on the db37 f connector to the ecu , everything seemed to be o.k except for pin 37 , that reads 12v and should be switch 0 v for fuel pump relay , also pin 33/34 & 35/36 should read 12v i think but because i have wire injectors to O/P 4 and it is not giving 12v with ignition. I'm sure it is something small but what i don't know ??

[Cable_ties]

i tried to edit my above post but i was too late

Ignor the above attachment it is the wrong one

The correct one is attached here

[Cable_ties]

no matter what i do i cannot get 12v from o/p 4 , it creeped upto 7 at some point, tried a couple of reply boxes, im thinking it could be the pin or the wire anyway i have scrapped the idea and opted for a couple of standard relays, see how i get on .

[Cable_ties]

Well at last thats sorted that , i just cut the relay pack out and wired in a main relay and fuel relay , the pump is now priming as it should

Couple of things i am unsure about was injectors and coils, i have pin 32/33 to injector bank (1) and 34/35 to injector bank (2) and the other wire i have sent to 12v with ignition on
and the coils i have spark-out (A) to pin 36 and output (B) pin 6 with the other wire to 12v ignition on, i also had the cranking wire going to the relay I/P 6 i have wired this straight to starter solenoid, is this correct about the injector and coil wires going to 12v with ignition on ? and the cranking wire should it go to the starter solenoid ?

should i see 12v on injectors and coil wire with ignition on or only when cranking ?