I'm having trouble with my 04 FX4 with electric switch on the dash not going into 4wd. I already replaced the actuators at the hub and the little switch behind the battery on the firewall.

Replacing the actuator fixed the issue for a short time.

No 4x4 will not engage if I switch to 4h when going down the road very slowly or when switched at a standstill. However, if I reverse a tiny bit, it goes in every time. When it is not in there is a terrible grinding that sounds like it is coming from either the driver's side hub or possible near the center front of the truck.

Could my actuator's at the hub have gone bad already causing it to behave this way? Do I need to replace the whole wheel assembly? Is it something in the transfer case? What would make it go in when reversing (and stay in when driving forward), but not go in when moving forward slowly.

Thanks for any insights or ideas.

 

Put the truck up on jack stands so the front wheels clear the ground but the rears are still on the ground. Engage 4x4 with the key to the ON position. Get under the truck and try to turn the front drive shaft. If the t-case is OK the front drive shaft should not turn. Come back with the reply and we can see what is wrong.