Too many things "wrong" happening so anything offered here would be pure speculation and possibly not at all helpful.

Haynes etc manuals are not that useful for what you're encountering---at best they have generic topics that rarely cover anything so specificially its helpful. Here's a link specific to your van:

1989 Ford Econoline and Club Wagon Electrical Manual: eBay Motors (item 400144715757 end time Sep-15-10 12:37:01 PDT)

Or this one--cheaper, same thing:

http://cgi.ebay.com/ebaymotors/1989-FORD-ECONOLINE-VAN-ELECTRICAL-SERVICE-SHOP-MANUAL-/380229718423?pt=Motors_Manuals_Literature&hash=ite m5887751197

Its priced a bit higher than I've ever paid but I did only a quick search. You typically won't find a factory manual like this on Amazon---just more Haynes and Mitchell Manuals etc.

This is what you need to get started---everything else is just guessing!!

HTH