I've got a 2005 F-150 (5.4 triton) with about 35k miles that I rarely use in 4x4 mode. The other day, after stopping to fill up with gas, the truck 4x4 Lo light was on after starting it. The dashboard switch was still in 2H mode as I never switched it. I first thought that the dashboard light might be in error, but when I began to pull out of the gas station. the truck was in fact in 4x4 Lo. I had forgotten how to cycle it back to 2H so I slowly drove about 3 miles home at 20 mph. Once home, I re-read the tranny sync sequence and managed to get back to 4x2. I called the dealer who never heard of a truck getting into that Lo mode w/o activating the switch and suggested that I just monitor it. I read a number of forum threads discussing the IWE and solenoid problems, but all of those threads dealt with issues of not being able to get too 4x4 mode. Has anyone ever had or heard about this issue? My biggest concern is that I leave in a month for a 2000 mile trip to Louisiana, towing a cargo trailer and I'd hate to inadvertently switch into 4/4 when traveling 60 mpg on a highway. Any guidance or help would be greatly appreciated. Thanks in advance.

 

I have never heard of this happening either. But I would suspect an electrical problem. The switch works with voltage supplied to the correct solenoids and the shift motor to engage 4wd. Something is getting voltage to engage the 4Lo that shouldn't be getting voltage with the switch in 2H position. Could be switch or in the wiring. Perhaps the Ford shop manual could shed more light on the problem.