Good Day, all:

The car: 99.5 A4 2.8
VagCom version: 311.2 (older, I know, but she works). Serial cable connection.

Problem:

It's my wife's ride. On the way home today it starts running rough as hell, throws a blinking CEL. She limps it home without too much trouble. I immediately suspect a bad coil, but break out the Vag to make sure. I go to connect...and get a Code 3- port working, no communication. Odd, I think, as I've had this exact Vag setup on this exact laptop talking to this same car just about a month ago with no problem. Ok, so Windows Update or something has screwed me. I spend 30 minutes screwing with the laptop....nothing. So, I decide to check it on my A6. Connects the first time! Walk right over to the A4.....no connection. I know there's no communication difference between the two cars, as I've owned both for years and use the exact same settings to talk to both cars.

I'm at a loss. I disconnected the battery for about 5 minutes, reconnected it...no dice. It just won't talk to the ECU! Other than something like a bad wire, are there any fuses or something else I could be missing that would cause this to happen?

Any/All ideas welcome!

Thanks!
-Red

 

have you checked the faq on the ross-tech website?

 

Indeed, I did. They had some suggestions based on no communication at all, but my problem isn't that...It'll talk to the A6 the same as it always has, but not to the A4 all of a sudden. Ross-Tech doesn't mention anything about a very odd situation like that.

-Red

 

do you have an aftermarket radio in the car, or is the ABS light on?

 

Nope...no aftermarket radio or ABS warning lamp on. She's box stock with the good ol' Bose noisemaker

 

have you checked the fuses? just an idea.

 

Yup, I went thought the fuse box. No dice there.

Sidenote: why do they like acting up when it's getting cold out (I'm in Jersey!)

Thanks, all!
-Red