Sorry if this gets asked a lot. I searched these forums looking for some guidance and didn't find an issue quite like this.

I have a 1996 Cherokee Sport, stock beside some minor suspension work.

Everything seems to be functioning normally. Runs smoothly, lights work fine, cluster is fine, no CEL. No reason for me to pop the hood outside an oil change in a good while.

The problem: I went in for its emissions testing and it refused to communicate with the shop's scanner. I have a scanner of my own that I haven't had to use in a while, and the Jeep wouldn't communicate with it either. I tested the scanner on my late-model Ford, and it does in fact work.

At the DLC, I tested for ground on pins 4 and 5, and battery on pin 16. Checked out fine.

What didn't check out, though, were the two CCD BUS pins, each of which read around 1.7V to ground. I also checked the resistance between them, which was 120 ohms.

This is where any guidance I've found becomes a little muddy.

If anyone has had this issue and/or knows where to go from here, I could really use the help.

 

For my 97, a couple of the pins backed out of the connector ever so slightly. See if pushing them in from the backside once the scanner is connected helps. Those terminals arent very tight to begin with.

 

So I looked at what is connected via the CCD bus and began unplugging/retesting.

Turns out, when I disconnect the TCM behind the panel under the glove box, the scanner works.