Hi all. I've been reading the forum here for a quite a while and have received some great information and learned a ton but now I need more help. I have 1990 GMC 2500 Suburban that won't pass emissions (high on HCs and CO) so I've been trying to get WinALDL up and running to see what the sensors are doing. The truck seems to run fine but smells rich. Anyway, I searched and found that I had the transistor wired in backwards, fixed that and started to get some data. (tested it on my 1990 Jimmy since it's in the garage and it raining here but from what I've been able to gather the ECMs should be the same - 1227747) All I get is the MW2 (whatever that is) and every now and then the PROMIDA, both from the RAW Data tab. Messed around with it for a while and it quit. I'm not using the resistor between ports A and B on the ALDL - tried but didn't make a difference. Also made sure that I didn't have the serial ports backwards. Any thoughts? I'm getting a little frustrated with the silly thing. I'm running WinALDL version 1.09e on a Dell laptop with Windows XP. Thanks for your help on this and all the other info. This has to be one of the best sites on the net! Oh, and i'm already addicted!