Good afternoon everyone,

Long time follower / reader and first time poster. I've learned a lot from this forum and have saved a lot of money from the great advice. I've searched for OBD problems / solutions, but none of them fits my current situation.

Vehicle is a 2012 Chevy Suburban LT with 225K miles.

The problem: The OBD won't connect to the scanner at the emissions testing stations. I've taken it to the dealer, and their scanners connect just fine. They were able to read and reset any faults I had. They even wrote on the invoice that they have NO problems connecting to the OBD port in their shop. Although this was a good explanation, the emission testing station didn't accept it; if it doesn't connect to the testing stations's scanner, it's not a "PASS".

I've taken it to a mechanic friend of mine for a second opinion. He plugged his hand held scanner into the OBD and it didn't connect. But when he plugged his big Snap-On scanner into the OBD port, it connected and read fine. Like the dealer, he didn't see a problem since his scanner connected without issue. I took it to another mechanic, and had the same result; hand held scanner didn't connect, but the big Snap-On scanner did.

There's been a lot of back and forth between me and the testing station, but they won't "PASS" the vehicle if they can't connect to it.

Has anyone see this sort of problem before? Any help would be greatly appreciated. The late fees are getting expensive and hate to get rid of it since it drives just fine.

V/R,

Chevy_Scout

 

Welcome to the forum. The only thing I could think of would be to take one of your mechanics along with his scanner and show them that their's is the problem.

 

Appreciate the welcome. I've brought this up to the foreman at the testing station and he said it didn't matter if they can't connect to my truck.

V/R,

Chevy_Scout

 

Sounds like you have some "not my job" government type people working at your emissions facilities. Is there a different one you can go to?

There might be some discrepancies in how diagnostic tools connect. For example, there are two different ground pins, so use a multimeter to make sure you have a good low resistance path to ground on both of them. (search OBD pinout).
The only other difference I can imagine is how the tools get power. Some may have their own power source, whereas other may get it from the OBD port. Again , measure the pins.
You may end up needing to see an auto electrical specialist. Most mechanics are weak in electrical diagnosis.

 

That's a great sugguestion; I'll check the resistance once it stops snowing.

 

I would've expected similar; to him rules are rules, and not uncommon with anything even remotely associated with government....

 

Following rules and being helpful aren't exclusive.

 

Finally got a chance to follow up with this:

I'm getting 14v between Pin 16 and 4, as well as 16 and 5. When I check the resistance, I"m getting 33Ω from Pin 5, but nothing from Pin 4.

Any thoughts?

V/R,

Chevy_Scout

 

33 ohms is too much. Should be less than 1 ohm. Check the ground connection.

 

This might sound dumb, but which ground connection?

V/R,

Chevy_Scout