Making an offboard for tuning
 

I have heard of people with bonnies having problems writing PCMs with tuners while the PCM was in the car, with some DIY directions and a trip to Morad, one of the benefits of living in cleveland :D, i got it all fabbed up and am proud to say i have had a 100% success rate of writing PCMs

unfortunately i didn't think to take any pictures while making it but heres the end result
https://www.gmforum.com/howto/tech/p...1137717409.jpg
here are the connections that need to be made
https://www.gmforum.com/howto/tech/100_1198.jpg
here is the connector, it is the blue harness from the pcm and the OBDII connector, the 2 wire hanging out are for power
https://www.gmforum.com/howto/tech/100_1199.jpg
the battery charger i use to power everything, this way no losing the pcm mid-write due to low battery voltage
https://www.gmforum.com/howto/tech/100_1200.jpg
offboard and power
https://www.gmforum.com/howto/tech/100_1201.jpg
simply connect your pcm, don't forget to tighen the screw ;)
https://www.gmforum.com/howto/tech/100_1202.jpg
then all i have to do is connect my dhp interface
https://www.gmforum.com/howto/tech/100_1203.jpg
turn on power, i used 12 low at first b/c i didnt wanna fry the pcm, but couldnt connect so i tried 12 high and no more problems, not in the pic but there is a switch for ignition power built into the harness
https://www.gmforum.com/howto/tech/dhpwrite.jpg
mid-write, battery voltage is showing ~14v
https://www.gmforum.com/howto/tech/dhpwritedone.jpg
and success! all done in about a minute
BillBoost recommends using an old computer power supply or 12V power supply from Radio Shack for overamperage protection.

if anyone is interested in parts for making one i can get them pretty cheap, or i could get the parts, fab it up, test, and ship it to you