well mitch,
actually there are service manuals for these trucks, the dealer just doesn't want to sell you one or help you in any constructive way for you to do it on your own. They want you to call them in and give them the work more than likely, unfortunatly some dealers are like this to insure they get business and keep others from working on them :o/

Of course it doesn't always work that way does it ;o)
Now personally i do not have a manual for this unit but i'm sure if you post your problem in here there are those that would be more than happy to help.