Turning on 4x4 for first time in years what to do first?
 

99, 5.4, electronic 4x4

I haven't used the 4x4 in years. the last time I tried it, it didn't work. One-tire-fire only. I have since replaced the pumpkin sensor, and a plethora of other issues that may have contributed to the 4x4 not work. I'm gonna kick it on this weekend or next, and wondered if there was anything I should do prior, or during to make sure i have the best chance of making it work properly.

Should it be warmed up? Cold? Flip the switch while moving? How fast? Any other tips?

Thanks guys,
-Mike

Try it in neutral first as that will most likely engage it. If you are moving it may not engage.

4H, anytime you like (shift on the fly). 4L = full stop and in neutral.

Oh- Don't do it while turning though lol.

And it won't work with bad vac lines or solenoids.

Excellent advice guys, thank you. If anyone else has something to add, please do.

And My Vac lines should be good. :unsure:

Yea, that's a common problem. As old as these trucks are, the lines can dry up and become brittle..at times shatter like glass.

I assume you're talking about the red and green vac lines? Have you had to replace any of those? If so, any comments or suggestions on how to test/find leaks and or advice on how to replace them?

Pink and Blue are 4x4. Green is EVR/EGR. Red is sometimes fuel regulator/main vac or canister.

Fantastic. I have no idea what I am talking about. This should go well.

Thanks Jbrew.

Fairly sure 4L also requires brake to be depressed while in Neutral to engage.

...or bad shift motor
...or broken shift fork ears

Basically, the whole system is failure prone POS.