Thread: ecu works in one car but not the other [SOLVED]

I have two 200sx SE-R's. One is a 95 that I just finished a auto to manual and vvl swap in. This is the car that I am having issues with. During the swap I used a manual engine harness and transmission sub harness. Both of these harnesses came off a 96 200sx SE-R. I also just jumped the inhibiter relay to get the car to crank over.

okay now that you have some backround on the 95, my problem is that only a G20 ECU from a p10 works. I have two other ecu's from b14's (one is tuneable) that will not turn on the fuel pump, but they will crank over the car and what not. Both of those ECU's are working fine as I tested them in my other car. A 96 200sx SE-R.

The fuse box is reciving 12v power at the fuel pump fuse, but the relay is not clicking. I have swapped it out with a known good relay.

I am very confused as to why these ECU's will not work in my 95. If anyone has any ideas please chime in.

edit
I found the short, it was in one of the interior harness plugs that go to the engine harness. A prong was loose on the interior side.

Jump pins 1 & 3 on the relay. The only difference, which should not matter at all, is how the p10 "Harness" splits 12v dc after the 15a fuse, where the b14 "harness" slits 12v at the 15a fuse.

Is this a b series harness or a p series?

i am using a b series harness, going to go jump it now and see how it works

well i jumped it but the fuel pump is not kicking on

Do you have 12v at the relay?

yes i have 12v at prong # 1 and 3

pring # 5 on the relay the black with yellow stripe has no power or signal. this is the wire that runs to the fuel pump

prong #2 has 5v signal and kicks the fuel pump on when its grounded. when it is grounded the fuel pump stays on and does not shut off after the pump has primed. the car will not start like this either. this wire is black with a pink stripe comeing from pin #8 on the ecu plug

also the fuse box has 12v running through the fuse just fine

What is your resistance from pin 8 on the ecu to pin 2 on the relay?

72.2 ohmz

Now check the resistance from pin 2 to ground.

with the key off i get 76.5 ohmz

with the key on i get 0 ohmz