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View Full Version : Invalid or no PCM



chevy42083
02-14-2009, 05:25 PM
Basics:
S-10 pickup, painless performance Harness, B-body PCM.
I've checked continuity for the power and the ground, and there is sufficient voltage (both while running and not). I checked the continuity between the tan wire at the ALDL and pin 30 on the blue connector.
Cable is a home made one that I bought from a friend. He made 6 cables at the same time, 4 of the other customers cables are known to be good. He said he also tested each before shipping.

I have tried a few different scan tools (mechanic grade, not walmart grade), and none of them have been able to read the PCM.

Datamaster is telling me "The ALDL adapter is working, but no PCM was detected. Check the cable connections between adapter box and the PCM. This can also occur if the DataMaster version is incorrect for the vehicle."

I've been running the ALDL Test program, and it seems to alternate between passing and failing. Just when I think I have it figured out, it's pointing to the right com port, I can get it to pass, then I unplug it, it fails, plug it back in and it passes (so I know it's testing the cable, not some other hardware).... then I start playing, go back and try again and it fails.

I'm also stumbling my way through the trial version of Tunercat, but really don't know what I'm doing. It doesn't show anything on the main screan, and I basically have no options. I don't know if something is SUPPOSED to show up or not. I have opened some other .bin files that I have saved, and the "tools" and "Tables" options will work. Pretty sure that's working like it's supposed to.

Winflash says:
"invalid response from PCM" from com 4
"No response from pcm" from com 3

The part number on my PCM is for a 94-95 b-body. Could the program inside it have been switched to a different vehicle (F or Y body?) or is that not possible?

The truck runs, but has a constant SES light. Is it possible for just the "transmitting" part of the PCM to be bad, while still running the truck?

Any suggestions?:frustrated:

chevy42083
02-16-2009, 11:51 AM
No ideas or input on any of it? Guess I'll be buying a new PCM... at least I can rule out one thing :frustrated:

EDIT: New pcm didn't fix it.

A new laptop did. Apparently the software or cable didn't get along with the USB to serial adapter. Got old laptop