OBDII code reader not connecting

2005 CHEVROLET 2500

180,000 MILES • V6 • 4WD • AUTOMATIC

CAMERONH

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I have a battery operated OBDII reader, to connect it to the car I plug it into the jack under the dash, turn on the reader, it tells me to turn the ignition to the "on" position, and once the car is "on" the reader tells me to press the link button which doubles as the power button. I have used this reader multiple times in the past, and it has worked just fine, but in this case, it just turns off and back on, without connecting to the truck. Any ideas? There are only four wires going to the jack under the dash if that helps.

May 14, 2022 at 7:42 PM

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JACOBANDNICKOLAS

AUTOMOTIVE REPAIR CONTRIBUTOR
110,190 POSTS

Hi,

There should only be four wires, so we are good there. What I need you to do is check for power and ground at the DLC.

If you look at pic 1 below, it is the wiring schematic related to the DLC. Note that pin 16 should have battery voltage at all times.

Pins 4 and 5 should have continuity to ground. I need you to check for these things at the DLC and let me know what you find.

Pic 2 is a pinout of the DLC to help.

Let me know what you find. Also, let me know the engine size.

Joe

See pics below.

Images (Click to enlarge)

May 14, 2022 at 10:06 PM