I have a 97 f150 4x4 with a automatic transmission and a manual floor shift for 4x4, my 4x4 only works when it want to,sometimes when I shift in 4h the light comes on and goes right in and 4x4 is engaged,and other times when I shift in 4x4 no light and will not engage,can anybody point me in the right direction,when I go to work on the dam thing it seems fine, but when I need it, it will not go in 4x4 for nothing...

 

You have the manuel shift control to begin the the process.
It signals a GEM module that in turn runs the tranfer case motor to the position you select 4H or 4L. Note that in 4L it changes the PCM shift programming as well.
Then the GEM operates a firewall relay to route vacuum to the front actuator.
With intermittant operation it can be anywhere along these paths.
You have to try and see where it stops the process either electrically or hardware wise.
A hint is the 4H or L lamp is lighted when the selected function is complete. If it comes on, goes off or flashes, any other time, it's a malfunction.
Good luck.

 

Ok I dont know if this makes any difference,But when I put the shifter in 4 low,my truck is in 4low,just the front wheels are not engaging and no 4x4 light ..

 

Look at the 4th line in my reply.
What does it say? If the actuator does not work no front drive!
The actuator is mounted on the front housing and is operated by vacuum.
Is the actuator good? Is the vacuum lines to the solenoids and actuator good? etc.
You have to translate the info offered and work on it.
Good luck.

 

come on dude give me a break ,I read all your answer including line 4,on the front differential,there is a actuator with a vacuum line and a wire going to it and the vacuum line is closed off with a bolt in it,but why does it work sometimes, if its not getting any vacuum at all,and when the light inside comes on the trucks 4x4 works great, with no problems..

 

as bluegrass said, there are two solenoids on the firewall. VAcuum line to to them. two vacuum hoses out of the solenoids go to the front axle. vacuum on #1 and it engages. Vacuum on #2 and it disengages. Just a small vacuum cylinder that goes in and out. If either hose is plugged, your screwed. Pull both hoses off and check vacuum as you move the shift lever.

 

Why do I not remember floor shifts?
What was Fords reason for keeping two systems in
The redesign.
Leftover parts?
I guess when I bought a new 97, it was an XLT with
Dash switch.
OP. Checking vac. Is a good start point.

 

With an answer like he gave in reply #5, he does not deserve any more help.
Comes here for help then offers back talk.

 

bluegrass I dont no what your problem is,I didnt think I was giving any kind of answer in #5,your the one that said {{read line 4 what does it say }}all I said was I did read it...how do you ppl stand this guy,

 

thnx khadma,and steve in ill ,im in ill to. i will check that vacuum tomorrow,but every time I go to look at it it works fine,