Ford F-150 4X4 problem

[herefish101]

My four by quit working on my 97 ford F150 4X4 extended cab 4.6 litre V8. It's a automatic system(servo shifted). there are no lockouts on the hubs, there constant. when i flip the switch to 4X4 the servo actuates the transfer case engauges the front driveshaft locks in and spins, but nothing from the front tires. is there something in the front diff that needs to engauge also, or is my front diffy toast?

[Scott K]

If you jack up all 4 wheels, does the front drive shaft spin? If it doesnt it can be transfer case, or shift motor, or Gem module. If the front shaft does spin and the front tires dont, then it is in your front diff. The f150's have a shift fork that can bind in the front diff, you may need to take it out, tear it down and clean/repalce the linkage in the front diff.

[herefish101]

yup front shaft spins with all wheels off the ground. that's exactly what i was wondering, is there a fork to engague in the front diffy, i'll have to dig into it tomorrow. thank you very much for the info.

[Scott K]

Before tearing everything apart. At the vacuum modulator on the front diff, get a pry bar behind it and move the linkage all the way in, then all the way out a few times in case it is just seized a little.