The Alldata suggestion is what I have done for service info. However, if you want another source of repair info, Helm Publications offers the factory service manuals (same stuff Alldata uses for the most part). The interface over there at Helm is pretty clunky so you kinda have to know what you're looking for. Now that "shop manuals" are over several books for complete coverage you'll need to look in "Shop/Service Info" in the pull down menu from the 1992 Thunderbird category. That will take you to two listings for the Shop Manual ($40.00), Powertrain and Emissions ($42.50). Then you go up on the menu to Electrical Troubleshooting manuals for the Electrical and Vacuum Troubleshooting Manual (EVTM) for another $22.50
And now you know why I chose the Alldata route