4x4 Full Time Problem....

When I shift into 4x4 PT, my dash light comes on and lets me know that I'm in PT4x4. The problem I'm having is when I shift into FT4x4, The indicator light stays in PT. Sometimes it will kick in after driving for 10-15 minutes. When it does finally kick in and when I'm ready to shift back to normal, the indicator light tells me that I'm in PT for some time...

I was told to check the vacuum line???????

I found the vacuum line on the Transfer Case this morning. I follow it up & over the Tranny, from there I don't see where it ends up.

Where does the other end of that vacuum hose end up??

Chiltons and FSM don't show the other end.

The most common vaccuum leak is at the 4 plug connector on the tcase. The lines go up the pass. frame rail into the engine compartment about about where the vapor collection canister is. From there they split off & go back down to the disconnect axle. Check for leaks at the vaccuum actuator on the axle housing too, this is pretty common. I believe this system is tied into the large vacuum accumulator that is behind your front bumper, if these lines are leaking you'll have problems too.

You should also find (in the corner by the blower motor, IIRC) two small vacuum switches that look like little blue cannisters (about 1/2"x1") on brackets - these are the vacuum switches that engage the lights. Check the lines to these as well. I don't recall exactly where they trace back to, but I do know that the vacuum signals to these are not entirely dependent upon shifting (I see a light lag on my 89, but 4WD kicks in and out right now.)

5-90

check to make sure all your tire PSI are the same or close.

same problem i had a while back. one tire was much lower than the others.

vintagespeed said:

... Check for leaks at the vaccuum actuator on the axle housing too, this is pretty common...

Click to expand...

No vacuum disconnect if the vehicle has full-time 4WD. Selec-Trac never had the dosconnect, only Command-Trac.