I am trying to log data using WinALDL from my 7747 ecm. Engine off, key on I get the flashing green 20, all data fields on the raw tab are filed and all the sensors show data. Once I start the engine, it starts flashing red, the raw tab only shows partial data and the sensors all are 0 or default values that don't change. This is not 100% of the time but close. I have driven it like this and it does seam to capture BLM data but I am concerned it's not right since I don't know if it's communicating like it should. I have a Windows XP laptop with a custom USB cable that I built. The fact that it works with the engine off makes me believe the cable is ok but I just started learning this stuff and don't really know what else to check.
Has anyone else had this issue or have any ideas what to check?
Thanks in advance.