Having some trouble with 5.3 need help

jesse102 · Aug 13, 2014

I have a 2001 5.3 out of a tahoe and a ecm out of a 99 camaro stock harness cut down and ecm has been flashed ......I can read through the obd2 port with ignition on........., but as soon as I crank the engine I lose all power to to my scanner through the obd2 port It will not power up with engine running either.............I don't think that's supposed to happen...........the engine will idle but as soon as I give it throttle it acts stupid any ideas ...........here is a video of what it sounds like

http://vid1104.photobucket.com/albums/h333/jesse1024/Mobile%20Uploads/trim976311C2-6F19-44EE-A7CD-11AF3B1CEA7B_zps05791b3c.mp4

zjtrey · Aug 13, 2014

Something isn't wired correctly…

how have you powered the obd port? does it have a dedicated ground?

I think the running issue is separate but maybe not depending on how you've powered everything else. only other one i've seen run like that had the throttle position sensor wired backward.

did you cut down the harness yourself?

jesse102 · Aug 13, 2014

I didn't do the harness myself the guy I bought it from had a shop trim it down.... the obd2 port has a constant 12v and the wire from the ecm and 2 grounds if I remember correctly .... It's just wierd to me that it has power with ignition on and I can read codes (which it says it has none) but as soon as I start it up to try and look at the scanner to find out why it's running bad it has no power to it

mdo817 · Aug 13, 2014

Went though this the other day, mine was a ground wire on the engine, mine was also a 4.0 jeep engine

jesse102 · Aug 14, 2014

zjtrey said:
Something isn't wired correctly…

how have you powered the obd port? does it have a dedicated ground?

I think the running issue is separate but maybe not depending on how you've powered everything else. only other one i've seen run like that had the throttle position sensor wired backward.

did you cut down the harness yourself?

Ob2 port is fixed went over wiring and it was not grounded..........still showing no codes guess I'll have to get someone to datalog it