Hi,
I have a 97 f-150 4.6l with 220k miles and the 4wd quit working. Neither 4wd high or low work, but it worked perfectly last winter. I have the manual floor shifter. Here's what I got. Shifter shifts into 4wd smoothly, 4wd lights light up on the dash, can hear a relay click, and front shaft spins. Had someone switch from 2wd to 4wd high and i felt the vacuum lines. The red line had good suction in 2wd. As soon as he switched to 4wd I had no vacuum from either the red or blue line. Does this sound like a broken vacuum line, the vacuum itself, or maybe something else?

Thanks,
Garrett

 

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