Any updates

 

not really, still havent found the problem. I went to the pick a part this weekend and got some PCM wires and an OBD 2 port and started making a make shift bench top harness to see if i can connect to the PCM, but had some other things come up and didnt get it finished yet. If i can find another PCM for a decent price id buy it to plug it in and see what happens, but they are more than i want to spend at the moment.

 

Ok, got an update. I went back to the pick a part and got some more pcm harness ends to make a bench top type harness to see if i can connect to the pcm out of the truck. With ground wires hooked to pins 1 & 40 on both the red and blue connectors, battery positive connected to pins 20 & 57 and also power into the OBD 2 connector and pin 19 ignition power and a wire going from pin 58 to pin 2 on the obd 2 plug my code reader/scanner connects just fine in about 1 or 2 secs with pass no codes present.

I then checked the pcm plugs and pins 1 and 40 on both the red and blue connectors have continuity to ground, pins 20 and 57 have 12V all the time and pin 19 has 12V with the key on.

I put the pcm back in the truck and plug into the under dash obd 2 plug and it wont connect. If everything has power and ground like its supposed to be then it should connect. I'm ready to give up on this but not just yet.

The only thing i came across is that with the key off pin 19 has continuity to ground, and with it on it shows 12V. With the key off and the neg test lead on the alt. stud and the positive test lead on pin 19 is shows -12V, could this mean that pin 19 is shorted to ground, but is somehow still able to send 12V to the pcm with the key on but is causing the issue im having with not being able to link to the the pcm thru the obd2 plug??

Any ideas?

 

i think Ive narrowed down the problem to the blue connector that goes into the PCM. I took the power, and ground wires and serial data wire out of the connector, and attached them directly to the pins on the pcm and connected to the under dash obd2 connector it links up no problem. plug the wires back in and it wont link.

 

Heres an update and the problem has been found, and corrected. There was a yellow wire on pin 59. with this wire removed it connects just fine, with it installed it doesnt. that wire was installed by the place that built the harness by mistake, as the 96 S10 doesnt have a BCM for that wire to connect to, the 98+ trucks do. So alot of work, frustration, time and money spent/wasted fixing a problem that now seems so simple. Guess we can all learn from this.

Peace

 

Glad to hear you fixed it.
All the problems are that way. They seem simple and easy once fixed, but it takes a lot of time and work to find that "simple" fix