91+ Power Transistor Module with a 90 ECU

[fudde]

2&3 aren't firing on my car. I have a 90 Talon and a couple of 91+ Power transistors. I read somewhere that a guy successfully swapped in the '91 PT into his '90. I tried it and can't seem to get it to work (car runs with the 90 PT on 2 cyl, doesn't run at all with the 91 PT). I've done all the testing of the coils, CAS, and PT module. Everything seems to be within spec. So I figured it might be the ECU.. I got an ebay junkyard special and swapped it in today. unfortunately the car runs the same.. So I swapped the coil pack, didn't fix anything.. And now I'm trying figure out if I can use the 91 PT..

does anyone know if this is correct and is it supposed it work?


' 91 PT Pinout
---------------------------
1- OC1 yellow/black
2 - IB1 yellow/red
3 - GND black
4 - NC
5 - (Tach output)
6 - +12V
7 IB2 Yellow Base
8 OC2 Yellow/Green

90 PT Pinout
---------------------------
1- OC1 yellow/green
2 IB1 yellow/base
3 GND black
4 NC
5 IB2 yellow/red
6 OC2 Yellow/black




Thanks much!

Pin 1 in the Pic is the repaired wire (I broke it trying figure out how to extract it) with the white heat shrink.. I swapped the wiring (OC2/IB2 - OC1/IB1) just to see if it makes a difference, but nada..

 

[Blackdragon84]

I had to put a new pt in my 97 a few weeks ago that the same Radom fIre. Have you tried testing the pt, it's a little tricky but can be done. Take a batter charger, some tiny clamps, a AA batter, and led light. Don't know the pin setup to test but some googling should find it

 

[fudde]

yeah I tested it and the two 91+ that I have, they all tested the same (transistors turned on when I applied a voltage to the base) Definitely something different about the 91+ though, aside from the tach output and 12V input). On a side note I should've check the voltages on the base pins (IB1 & IB2) from the ecu before I bought another ecu (I placed a meter in front of my windshield while I cranked the car, both pins were toggling 5V) - but I was kinda wanting another one.

I did cave and bought another 90 PT. Hopefully it'll be here in the next day or so to see if that's it.. but if it's not, I'm stumped.

 

[fudde]

So just in case anybody happens to run across this in the future...I guess I should have done a compression check before chasing down electrical issues.. I've got very little compression (30 psi) on 2&3.. It runs like crap just as if I was getting no spark.. I wanted to believe it was an electrical issue because I have less than 1K on a rebuild... ugh.

 

[jdarnold1990]

Did you tap the black and white wire into the black and white wire on the coil pack plug?

follow this guide and try again. and try your compression test again. i hit low numbers on mine it was like 50 psi the way across and borrowed my friends compression tester and it was good.. http://www.dsmtuners.com/forums/art...4-ecu-swap-into-1990-dsm-ignition-wiring.html