Hi everyone, I realize that I might not be asking my question on the correct forum as I have a 1998 lincoln navigator with a 4x4 issue, but I thought I would at least try, maybe some one who has a spare minute can offer some input. As the title suggests, the front wheels are not engaging on my navigator when in 4wd. I saw a very well written article detailing this issue here on the forum for a 97-03 F150 4x4 diagnostic with manual 4x4 shift. My truck has a switch on the dashboard with 4 settings: 2H, A4WD, 4H, 4L and the 4 wheel drive does not engage in any setting, even after driving a long time it still does not engage. I can tell that when I slip, the rear end slides around but the front gets no power.

A little background info that might help to eliminate some possible causes: this issue actually began about a year ago around this time of year. It was very cold outside, and I do not have a garage so I couldn't work outside, so I took it to a shop which ended up being a huge mistake. When I first took it to this shop, the transfer case motor was replaced, I took it out for a drive and it still didn't engage. I took it back immediately, and after a couple days, the shop manager said the GEM module was faulty so that was replaced--still didn't fix it. The third time I took in and the manager said that two speed sensors were bad, they said that that should fix it for sure. It did work for the remainder of that winter, but fast forward a year later now, the 4x4 stopped working again. Anyway, I am not to familiar with the automatic switch 4x4 system, and I do not know exactly where to look to diagnose the problem. When I switch into 4H, the 4x4 light turns on the dash turns on and the relay clicks, but nothing else happens. If anyone has a 4x4 F150/Expedition with a similar switch 4wd system, please let me know if you have some spare time, any input is greatly appreciated. Thank-you all!

 

Check fuses. If the relay is clicking that means it has power, but do the mechanisms that actually move the driveline have power?

I don't know how that system works, never seen one, so the above is just a guess. Sometimes it is the simple things. I suppose it is possible one of the required components is not working also, but you would have to have a mechanic look at it or check/test the parts yourself.

 

Update: I tested out the 4x4 again today, and it works in A4WD properly, however, 4H and 4L do not work at all, it remains in two wheel drive when in those settings. When I switch from A4WD to 4H, the 4x4 light turns on the dash but like I said nothing happens. Anyone experience a similar problem?

 

Need to have it scanned. Sounds like a GEM problem to me.

 

I have a similar problem.. Does it flash /click back and forth when you leave it on one setting?

 

Sorry for the late reply, when I switch from 2H to A4WD there is no click or light, but the front wheels do engage. When I switch to 4H there are two clicks and the 4x4 light appears on the dash but the front does not engage just remains in 2 wheel drive. When it used to work before on 4H, you could hear a clunk and feel the front wheels get power.

I also have a scan tool/code reader that can read live data but there aren't any codes stored in the PCM. I guess that wouldn't help me anyways if it is in fact a GEM issue. It's really weird since there are no codes or warning lights on the dash or anything like that. I would hate for it to be the GEM module again, just one year after replacement. A new OEM Motorcraft GEM module was installed and parts+labor cost well over $1000. I guess the only option remains is to take it to a more reputable shop.

 

Do a quick search online you can find the 4x4 control modules a lot cheaper. I replaced one on my daughters durango and the total cost was under 200 bucks. They are also plug and play if its just a 4x4 module. Good luck

 

unfortunately this is the downfall of these electric shift units. when they work they work. when they don't work they are a royal pain to figure out what is wrong.
that is why if it does not have a shifter on the floor with manual locking hubs, it will never be in my driveway.