2004 F150

I have a 2004 F-150 5.4L (160,000 miles) with a problem with its 4 wheel drive. I recently replaced both bearings and actuators on the front end with OEM parts, but recently I have discovered that the vacuums that engage and disengage the 4 wheel drive will not turn off causing the truck to stay in 2 wheel - this has been a problem even before parts were replaced. When the tubes that are connected to the bearing/actuator are removed the 4x4 kicks on. Any information on this problem would be greatly appreciated.

Purplehazeir

There are some vacuum valves that get wet and then need to be replaced. I believe they are on the firewall on the passenger side.

PBRFan

Yes on the passenger side fire wall. Looks like this.

2004 F150

Thanks everyone