Hi, I'm having a minor issue w/ the 4x4 Hi on a 2003 FX4. After switching back to 2 Hi there is something wrong. At above approx 45 mph, there is a very noticable vibration running througth the vehicle. I think this could be the hubs still engaged, but I'm not familiar enough w/ how the 4x4 system works in the truck. I don't think there is any power going to the front wheels though, there is none of the normal binding which occurs when making a tight turn while in 4x4.
I've tried little things to try and make it go away; switching back in/out 4 Hi, going in reverse then forward. Sometimes one of those things seems to work and the truck then drives as usual, but the issue seems occur about 50% of the time when I switch out of 4Hi. It's mostly annoying, but I think I could be doing damage while driving at the higher speeds if it is infact the hubs that are still engaged??? I'd appreciate any information that can be shared on how the ford F150 4x4 system works, and/or what this issue may be. Thanks.

Frank

 

A 2003 does not have hubs. ore than likely the front diff is not disengaging. This could be a similar problem that many have with the front diff engaging, only it would be on the disengage side. Since you do not have a problem engaging the front diff, my guess is you have either a vacuum leak on the line from the disengage solenoid to the vacuum motor, or you have a bad disengage solenoid.

 

Thanks for the reply. Do you know how easy it is to do these fixes on your own? I'm hoping w/ a little help from a Chilton/Haines book I can manage it.

 

Replacing the solenoid is easy, assuming that is the problem. I would trace the vacuum line first and see if there are any cracks or breaks in the line. If a crack, even electrical tape could be a temp fix. As to which solenoid is the lock and which is the unlock (there are 2 on the firewall), I am not sure.

 

here is a quick test to make sure your truck is going out of 4x4. drive down the road (dirt if you can find one) put the truck in 4 hi verify the light comes on and stop get out and try to spin the front drive shaft by hand. If you cant the truck is engaged. Start driving again put it back in two wheel. verify the light is off and stop get out and spin the front D/S again by hand. If the D/S spins your disengaged. From there you should be able to trouble shoot the problem more. GOOD LUCK