First off I am new, so please forgive any ignorance on my part. I have a 2001 F150 SC 4x4. Currently the 4x4 is not working. All of the fuses have recently been checked/changed. I will describe the issue after having disconnecting and reconnecting the battery. The below descriptions have been done while in Park and in Neutral going into Drive, both with the same results.

I start the truck with the on-the-fly switch in 2x4. When the switch is turned to 4x4 High, the 4x4 high light comes on but 4x4 is not engaged. I do however notice a sound from the passenger side of the dash when the switch is turned from 2x4 to 4x4 High. It sounds to me like a very short and faint buzz or hum. Is this a relay of some sort?

Then, when I turn the switch from 4x4 High to 4x4 Low, nothing happens and the 4x4 High light stays on instead of the 4x4 Low light coming on. I also don't notice the sound previously mentioned when switching from 2x4 to 4x4 High.

Lastly, when I switch back to 2x4 from 4x4 High or 4x4 Low, the 4x4 High light stays on. Even when the truck is turned off and cranked back up, the 4x4 high light is on but the truck is in 2x4. When the battery is disconnect the 4x4 high light goes off until all the above is repeated again.

This may or may not be related but my horn does not work.

Also the ABS service light is on. If I start the truck with my foot on the brake, the ABS service light wont come on until after I take my foot off the brake.

Thank you guys so much for your time, input, and suggestions.

Dave

 

Could be a few things, but the 1 thing that comes to mind, when was the last time you had the battery checked ?

Usually the cluster also sweeps when there is an issue in the MY range you have, but 2 items acting up could be the battery, or 2 separate issues.

Start with a simple voltage check of the battery, and see what it is, just as a starting point.

Did you check to see if the transfer case was engaging ?
Lift and support the front of the truck so the front wheels are off the ground ( take safety precautions, chock wheels, jack stands, etc )
Key on, engage 4x4 and try to turn the front drive shaft.
If it turns it is a problem with the transfer case.
If it doesn't it is a front axle engagement problem.

I am expecting the front drive shaft is going to turn, while engaged in 4WD. If so, the transfer case shift motor is not working. Could be the connector on the transfer case or the transfer case shift motor itself.

You can try hamering the transfer case with a dead blow mallet ( do not use a metal hammer, it can damage the case ) while someone shifts the truck from 2WD to 4H.

Few things to start with.

 

Thanks Scully. I'll start there. It may take me couple of weeks to get back with answers. I'll let you know.