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Old 02-04-2019, 09:56 PM   #24
BR3W CITY
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Join Date: Sep 2009
Location: MKE WI
Posts: 7,128
Re: OBD gremlins ... need assistance please

Quote:
Originally Posted by HSRACER View Post
I am trying to find a pin out diagram of my computer. It is the blue and greeen connector version.

Do you have any idea which color wire is the ground and which is a triggered ground? I would guess the solid one is ground and the white and black one is triggered.
Pin 4 is chassis ground, 5 is "signal ground"
It may not be the problem, but GM does differentiate them.

The codes you posted would mostly be set to not report, so they exist on the log but don't trigger the MIL.

The "U" code is the one we're having the issues with. Thats the one actually indicating the failure on the OBD circuit. If your actually getting low voltage on the data port it means you have wires crossed somewhere. Put a meter on the data line and see if it reads anything less than 2.5v, as that's what should trigger the DTC.
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