I'm trying to help out a friend of mine with this and I only started on it tonight so the information I have might be a little limited.

The car is a 1932 Ford with the engine, trans and PCM out of a 2000 Camaro. Everything was working fine until a few nights ago when he left the key on all night but when he charged up the battery it'll crank but won't start anymore.

The first thing I did was to see if I could connect to the PCM with HP Tuners but it doesn't look like the OBDII port is getting power since the little green light on my HPT interface didn't come on.

I then started applying power directly to pins 19, 20 and 57 according to this diagram:

https://ls1tech.com/forums/16382118-post7.html

While doing that did activate the fuel pump relay, I still wasn't getting any power to the OBD port.

Any thoughts on what might have gone wrong from leaving the ignition on all night? On one hand it looks like it might be a power issue as those three pins are supposed to be hot at all times with the key on but weren't. On the other hand, even with those pins jumpered, I still couldn't get any power to the OBD port which leads me to believe the PCM may have fried.

Thanks in advance,
Christopher

 

Sounds as if your Fuse/relay power is missing. All leaving the ignition on all night would do is leave relays and such on . Maybe a bad relay , cant be sure without actually being there with a test light. But if you applied positives to the ecm , you didnt have them there to begin with . If you lost power to the ecm you most likely lost power to your injectors,coils,sensors, etc... All you did was bypass the missing power to the ecm and not everything else. Grab a test light , turn the key on and start probing for where the problem is .