I have used tunerpro, with success to communicate with a '165 running $83A (2.5L S-10) but cant quite figure out the right byte string for scannerpro. I know what the first 3 bytes are but what about the fourth byte in the mode1 command? here is what the A099.DS says : DATA STREAM A99 SPECIFICATION ENGINE USAGE: 2.5 L TRUCK TBI LN8 1990 S,T,M TRUCKS (VIN=E) 2.5 L TRUCK TBI LN8 1991 S,T TRUCKS (VIN=E) DATA PIN : READ DATA ON PIN "M" OF ALDL CONNECTOR BAUD RATE : 8192 BAUD BI-DIRECTIONAL ..PAGE MODE 0 (RETURN TO NORMAL MODE) ALDL REQUEST: - MESSAGE ID = $F0 - MESSAGE LENGTH = $56 - MODE = $00 - SUM CHECK ECM RESPONDS WITH NORMAL MODE MESSAGE *F97* MODE 1 (TRANSMIT FIXED DATA STREAM) ALDL REQUEST: - MESSAGE ID = $F0 - MESSAGE LENGTH = $56 - MODE = $01 - SUM CHECK THE ECM WILL RESPOND WITH THE FOLLOWING MESSAGE: - MESSAGE ID = $F0 - MESSAGE LENGTH = $95 - MODE = $01 - DATA BYTE 1 . . - DATA BYTE 63 - SUM CHECK So when I edit the ADX file it should be just "0xF0 0x56 0x01" ? should there be a 4th byte here? and if so what is it? do I need to calculate a checksum value for the first 3 bytes? A bit confused here, I'm sure its something really simple. Thanks in advance. Punisher

okay, nevermind, I figured it out, after about 6 hours of searching.

For those having the same problem, you can save the adx file, and then re-open it and scannerpro computes the checksum byte for you.

Also you CAN import ADS files, just save them as an ADX right afterwards and then load the new ADX. When you load the new ADX all the info from the ADS will become visible.
When you first import the ADS file all the fields in the editor will be blank and it will appear like you have imported nothing at all, but thats not the case, just save it and then load the new file.