If the blinkers work then your taillight wiring is bad.
Relay # 302 is the trailer tow battery charge relay in a 2002 Ford Expedition
I was looking at the 2000 Ford Windstar Owner Guide and it shows : Trailer towing requires the optional trailer tow electrical package " may require use of an additional medium duty trailer tow option package "
A 2010 Ford F-150 with the Max Trailer Tow Package can tow a class-leading 11,500 pounds.
dose it have tow package
Max trailer weight is 8100 pounds.
without tow package it can handle 1 ton (2000 pounds) with tow package 3500 pounds
If you have a hitch installed under the rear bumper and round 7-pin wiring.
The towing capacity of the Ford Expedition depends in part on the year of the vehicle and how it is equipped. The typical Expedition can tow between 8,100 and 9,200 pounds, adequate to handle a 4-horse trailer.
If it came from the factory with the tow package option, yes.If it came from the factory with the tow package option, yes.
if it is prewired for a tow package it will have a trailer brake control in the dash most 2000 were not prewired but you can buy the kit that plugs into the vehicle loom without a great deal of trouble
According to the owners manual - relay 203 is the Trailer Tow Backup Lamp Relay