My 97 f150 started to try to go into 4x4 the other day. I was driving down the street and heard a clicking coming from my dash area,just as i looked down there was a clunking noise as the truck tried to go into 4wd without the shifter lever (MSOF)being moved. I put the truck into 4wd and the clicking stopped but as soon as i put it back into 2wd the clicking and clunking started again. I drove the rest of the way home in 4wd ,when i got home i put the truck into 2wd and disconnected the wire to the 4wd indicator switch , this stopped the clunking noise as the 4wd could no longer power up but the clicking noise continued for the rest of the day. Now the light on the dash for 4wd will not come even when i shift the truck into 4wd on and no more clicking at all. Any ideas where i should start looking first? Thanks.

 

I doubt whether it was truly trying to go into 4wd, but that for some reason the front diff was trying to engage. In your case, the shifter must be moved to go into 4wd. I would start looking at the GEM module first as that is what tells the front solenoid to engage the front diff.