I have an '01 crew f-150. I'm having issues with the 4x4 system. I changed the 2 vacuum solenoids on the firewall already but am having the same problem again. I flip the switch to put it in 4 wheel high or low and it is not engaging. I can here the transfer case click in but the front wheels don't spin like they should. Any ideas. The solenoids bad? Bad switch? The weather here is starting to suck and would really like to have my 4wd incase I need it. Oh by we played with the electrical connection to the solenoids it worked for a few hours but haven't got it to work again since.

 

define "played with".

 

Pulled them out to make sure they weren't dirty or coroded. Checked the connections to make sure they were tight.

 

probly the vacum powerd 4x4 actuater on the front diff if the transfer case is engaging

 

Is there anyway to check it before replacing