Diagnostic plug

[davidbrady]

Hey George,

You'll need an oscilloscope or a a logic analyzer to see what's happening on the 9600 baud J1708 datalink. You can also monitor the J1708 using your computer if you buy something like the busbee: http://www.usbee.com/busbee.html serial bus monitor, but that'll cost about $300.

I assume you're getting power to the ignition switched and un-switched leads and that you have a good ground. If not, here's the document for fuse locations: http://wanderlodgegurus.com/database/ind...0Locations

I scanned the LXi schematics but I can't find where the Pro Driver taps into the datalink bus. The diagnostic port taps in at the Allison ECU which is located in the generator cooling fan bay.

If all the powers and the ground check out, I'd be tempted to jumper around the Pro Driver datalink by running a twisted pair from your diagnostic port to the Pro Driver. I think we can assume your diagnostic port is functioning properly because you had your transmission jake brake preselect programmed recently from 4th to 5th.