e38/t42 connecting issues

i have a 2008 l76 truck engine
e38 ecu
t42 controlling the 4l80e
engine runs but cant seem to connect to hp tuners via obd2 port
one min it will say detect protocal error, then it will say boot loader time out , ecu not found etc
any help
fully charged battery
some of my other cars will connect instant and others wont
took the e38 put in my dads 57 read it perfect, put dads in mine read perfect wtf lol
mpv1 unit

likely a wiring issue with the vehicle. Try reading the ecm via bench harness.

Quote:

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Originally Posted by Bill@HPTuners

likely a wiring issue with the vehicle. Try reading the ecm via bench harness.

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its a stand alone harness , checked checked and rechecked wiring

well if the ecm reads in one vehicle but not the other, chances are its a wiring issue.