 97 F150 4x4 won't engage, now stuck in low
I seem to see this problem posted a lot, but no clear solution. I have a 97 F150 4x4, 5.4L Auto, with electronic dash switch. Had it hauling snowmobiles a couple of weeks ago when I discovered that the 4x4 wouldn't engage. Bad times. Dash light would come on, but no power to the fronts. Checked fuses, both OK. I noticed later that the '4x4' and 'low' lights stayed on, despite the switch on '2 Hi'. Went off a short time later and drove it home fine in 2wd.
Got her home and started checking different things after checking the web. First stop was the vacuum solenoids. Had power to one on '2 Hi' position, power to the other on '4 Hi'. That seemed right. About that time, I noticed that I could hear the engagement 'click' to 4 Hi and the 'chunk' to 4 Lo. Cool, must have fixed itself. That only lasted a couple of tries, then nothing. It was replaced by 5-6 clicks behind the dash whenever I start the engine, regardless of the switch position. Decided to take it for a test drive and realized CRAP!, it's feels like it's stuck in low. Doesn't feel like the front drive is engaged because the steering doesn't shutter on hard turn. I can get it to manually shift into 2nd, but it still feels like it's in low. Won't go over 15 mph without revving engine. Start the engine, shift to neutral, still won't disengage. Crawled underneath and tapped on the electric motor while my son switched through '2 Hi', '4 Hi', and '4 Lo". No change. Disconnected plug to electric motor and using a test light, discovered I'm not getting power to any terminal, despite which switch position it was in. Shouldn't there be power at some point? Checked the vacuum solenoids and realized that both power connector had a hot connector, despite switch position. (Used a meter when I originally checked them, so I don't know if they normally have power to the connector and activate through the ground. Didn't check them again with the meter.)
I've found a lot of similar problems posted, and a few possible solutions, but none seem to fit the same group of problems. Thought it might be the motor, but how could that be if there's no power to it. Even if the solenoids have correct power and no leaks, that only effects the front drive engagement, not the Hi or Lo engagement, right? The GEM module gave me some problems when I first bought the truck because of a leaky windshield, but that went away when I had the windshield replaced, over a year ago. Besides, none of the other issues I had with the GEM issue appeared this time.
At this point I'm stumped. Chilton manual is worthless. Pride won't let me take it to a shop. Can anyone think of something I might have missed and what to do to troubleshoot it? Any help would be appreciated. | 
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