[87chevy.com]

I dont have alldata access on this computer... do you have a 6l80e?

if so, probably the best spot to get the obd connection is at the transmission.... from this diagram, that might or might not be the same for your truck, its just one i found on lt1swap.com, those 2 wires, your splicing into..



these are similar to the gen5 swap harness I rework... can bus wires goes out of ecu, to trans, and trans out to BCM... in my swaps, i just use that BCM wire to OBD ports 6 and 14.. just splicing into the data stream may or may not lead to problems?

clint

Originally Posted by rodstored-72

Well…after more research & talking with my friend with the hp tuner software, not to mention nudging from a few board members… I FINALLY figured out the correct pin assignments to read the ECM!...
below is the obdii port pin out. This is for a E38 ECM from a 2013 chevrolet Silverado.
Pin 1 thru pin 3= empty
Pin4= signal ground
Pin5= chassis ground
Pin6= ECM pin28 (2500) tan/blk canbus(+)
Pin7 thru pin13= empty
Pin14= ECM pin27 (2501) tan canbus(-)
Pin15= empty
Pin16= batt. (+) const. power
For me I used pin J5 from the “X4” connector (640) red/wht wire for pin 16.
Thanks to 87chevy.com for the nudge to recheck everything again. I hope this will be a help to others and thank you all for the replies.