brian1115

I just bought Hp tuners and made a bench harness from sloppy mehcanics wiki page.

When I try and read the vehicle in hp tuners I get a message that says "detect protocol failed"

I have my bench harness wired so that there is no switch between 12V constant power and pin 19 keyed hot. Is this causing the problem? Do I need to add a switch there?

I have it wired as such:

PCM:

1 GND
19 IGN (+12V)
20 +12V
57 +12V
58 Data to pin 2 on OBD2

OBD2 Port:

pin 16 12V
pin 4 and 5 ground
pin 2 data to 58 from pcm

rpturbo

iTrader: (47)

What ecm are you trying to read? I do not have a switch in my bench harness. I will say, I did wire mine wrong the first time. Some how, it was easy for me to screw it up. I figured it out the 2nd time. I have heard some ecms do need a switch, IDK. I read the 0411/P59 setups.

Steve01SS

iTrader: (43)

I don't believe you need pin 57 Not sure where that came from.
You are using the blue connector right?

I have one wired like this and works fine. No pin 57.
http://www.gmtruckcentral.com/articl...h-harness.html

roughneck427

iTrader: (12)

PCM grd pin 60