Unfortunantly Winnebago has not posted all of the wiring documentation for your rig however this may help you resolve your issue:
The wiring on the rear of the Jensen Radio is on page 4 of the Jensen Manual: http://www.google.com/url?q=http://w...17z0Qr1WDI0aKw
Please note that you should also be able to use the front AUX input or USB interface as described on page 5 of the manual.
Winnebago presents wiring information for different rigs in many of their drawings. For your rig, use the "Series D" key.
Winnebago interface to your radio is on pdf page 6 (sheet 6) of http://www.winnebagoind.com/diagram/...ire_174637.pdf
Unfortunantly, Winnebago does not have the "IP Main" drawing posted (Body, 12 Volt wiring diagram). You need that to figure out how the speaker wiring is routed to the external audio distribution. Might try contacting them for it. Speaker audio is distributed over the 4 pin and 12 pin plugs shown in the jensen manual and page 6 of this drawing.
Additional information (mostly for DVD output from the Jensen) is located on pdf page 7 (sheet 6) of http://www.winnebagoind.com/diagram/...ire_175930.pdf
Dash radio is located at bottom at location A-4. You have to "know" what options you have installed in your rig to connect all the paths on that drawing. The option
"key" is on the bottom right of that page. You have to set components in the path to the correct position to use it.
The primary winnebago wiring diagram TOC page is Table of Contents
Hope that helps to some degree,