Join Date: Mar 2001
Location: Cody, Wy
Feedback Score: 0 reviews
Your's may be the same as my '91 and if I remember right, all my factory trailer wiring was at a plug one side or the other at the very rear of a rear fender. Probably the left because that's where my in-bed trailer plug is mounted. And mine did have an "always hot" 12V wire. Of course if a previous owner made changes in your case, all bets are off.
Heavy truck and diesel mechanic (thankfully retired after 30+ yrs)
'91 F-250 SC 4X4, 5spd. ATS Turbo, 3:55 diff.