2G No spark; ECU Voltage i/o?

[SubversionX]

Some of you may have been following along with my progress in troubleshooting my CAS. After getting that all situated, I think I've come across a new issue; Directly from the ECU with the harness removed, I am measuring approx. 5 volts DC but when I connect the harness I'm not getting any power from the ECU harness from pins 12 and 25.

I realized this when I traced back power to the ECU. I haven't visually identified any fuses that are blown. I read that this could be due to the MPI Relay; is this true? How should I go along troubleshooting the ECU? Where is power fed to the ECU from? Thanks in advance!

 

[steve]

I'm not sure that your trying to say.

The ECU activates the MPI/MFI relay when it sees the ignition switch put battery voltage on pin 82 which in turn puts battery voltage on pins 12 and 25.

You should always have 12 on pin 80. (backup power)

 

[SubversionX]

That narrows it down a lot actually when you put it like that. I was having starter issues as well, but then just built it on its own circuit and bypassed the MPI relay. I suppose I just ignored the actual issue rather than fixing it. Where is the MPI relay on a 2g, and how do I diagnose it with the multimeter? Thanks!

 

[steve]

http://www.dsmtuners.com/forums/newbie-forum/276071-mfi-fuel-pump-relay.html