1997 F-150 4x4 4.2l 114,000m
Can anyone tell me what the most common reasons for 4 wheel drive not engaging. I have no check engine lights, and my 4x4 light comes on but doesn't engage. Any things to check would be helpful like wiring, actuators, ect... Thanks

 

probably the vacuum-operated auto locking hubs in the front. that is a common issue for that year...and mine too

luckily i haven't had any problems with mine, but that would be the first thing i'd check. as far as how to check it, i don't have any personal experience but i'm sure someone else will chime in.

 

Yeah that is the first thing I am going to check. I am wondering if I can pull the pink and blue vac lines from the actuator and check them for suction? I will give it a look and get back with results. If anyone has any info on this please post. thanks alot

 

You do not have hubs. All locking and unlocking of the front is done at the diff. Front axles always turn, whether in 2wd or 4wd.
Most problems with the front, assuming the transfer case is working properly, is either a bad solenoid that sends vacuum to the vacuum motor on the diff, leaky lines to the front diff, a bad vacuum motor that moves the shift fork in the diff, mud or other debris blocking the fork from moving, or a broken shift fork.

 

When i bought my ford it had never had 4wd used so i drove for about a mile with it on then you heard it engage ... No problems since btw mine is shift on the fly if that helps

 

Hey guys thanks alot, I found my problem it was very simple. The blue vacuum line that engages the 4 wheel drive was broke and lucky for me it was right at the solenoid. So I repaired it and 4x4 works like new!!! I just want to say thanks to everyone on this fourm if it wasn't for all your help and other threads it would have took alot more time and money!!! thanks all

If you have a similar problem check out this thread!!!
https://www.f150online.com/forums/ot...um-system.html