- May 10, 2004
I know a lot of guys are trying to find the MFI/MPI relay, here's where it is and what it looks like on a 95 GSX.
I show the 95 still has both relays in the same unit but the FP relay now has only 1 coil (1 input). The 96-99 all have separate relay units.I haven't looked at the 2G wiring to see if the 9's still use the second input of if they use a different MPI relay. The later 2Gs don't, they use two individual relays.
Any thoughts would be appreciated.
Which pins have 12V? In one sentence you say 3 and 9 do have 12V, but the other says pin 9 doesn't. Assuming you are looking to see where pin 9 on the mpi relay goes, on a M/T car, it goes to the starter relay. You should only see 12V there when the car is cranking. The more important question is what do you see for voltage on pins 7 & 8 of the mpi relay when you are trying to start the car?
The car seems to be getting fuel (fuel pump whines and inlet pulses) but has no spark and no ECU boot. I fried the shit out of my ECU beyond cap replacement, and I got a matching one from a guy of craigslist. I opened the replacement and it doesn't look or smell fried. After putting the new one in I noticed its not booting, but the MPI does click... I will try to check the MPI relay across my battery this afternoon.
Sounds like the fuel pump side of the relay works so you should focus on the MPI side.
Since pin 10 has 12v all the time just go to the ECU connector with the ECU disconnected and ground pin 63 (or 66) and see if that turns on power to pins 102 and 107.
It's common for leakage to damage the traces controlling the activation of the MPI relay.
If grounding the pin turns the power on then you know the problem is the ECU and not the relay. (which would be the first place I would have been looking since I've yet to see a bad MPI relay but lots of bad ECUs)
I could test it across the battery by using some wire right?