[tsubaki]

Visually check to see if all fuses are good under dash and hood by removeing one by one (so not to get confused). If you have the book (in the glove compartment) on that vehicle it will usually list each fuse location, designation and size.
Don't take it as the gospel that the towing package was installed correctly by professionals. Most of the time dealers will send their vehicles to places like U-Haul and have them installed.
If you run into an impass, just add the T connector and harness and see if that fixes the problem (cheaper and quicker).