ECM Port not working right

[Phantom409]

Details: 93 Trans Am, M-6, OBD-1, 383 Stroker with a lot of bolt ons

Problem: My ECM port is not comunicating with the cars computer
I'm not the only person who has had this problem.
I had the car at a garage last year and they couldn't get thier scaner to work either.
I'm trying to get my DataMAster Software to work.
My laptop is running Windows 2000 Pro and all ports are working.
Any ideas on what it could be?

[Xenoculus]

PCM/ECM not responding

Try checking the tan wire leading from the OBD1 connector
to the PCM/ECM module for continuity. This is the data signal
wire. There is also a white wire with a black stripe that functions
for 'field service enable'. On some cars, you need to put a resistor
between this wire and ground to enable computer communication.
As far as I know, this isn't necessary on the 94 and 95 computers,
but your 93 (which is a completely different PROM based computer)
might. If both those wires as well as the ground wire at the OBD1
connector are good, you should be able to communicate with the
computer. Ground is on Pin A (top right), the field service enable
wire (white/black) is on Pin B next to it. Pin E (5th top) is your data signal
wire (tan). Those three are all that should be needed to communicate
with your PCM. If everything checks out OK to the PCM, and your
ground is good, try putting a 10Kohm resistor between pins A and B
and that might help to coerce the PCM into diagnostic mode.
If everything checks out ok from the diagnostic port to the
PCM, and the ground is good, and you've tried the 10K resistor,
and you STILL can't get the PCM to communicate, it's time to
question your interface, your computer, or your PCM.


Todd in Roseville