No 4-Hi

I have an '02 Silverado 1500 Z71. It has push-button 4WD, but when i push the 4-hi button it won't shift over. The light changes, but you can't hear anything. 4-Lo works fine, but no 4-Hi. Any ideas???

Does it have a SERVICE 4WD DRIVE icon in the message center?

1999-2002 most common DTC is B2725(?) Active transfer case mode switch. Switch fixes 99.9% with a message. Also need to make sure the ground on the frame behind the body mount between the LF wheel and LF door is good. Leaking windshield can drip water into the ATCM under the LH side of the dash too but I've rarely seen that. There are other issues as well....but I could type all night long.

no, there's no error message

Are you sure it's still in 2HI?

yeah. im pretty sure. i cant feel the resistance that i should.

You need to see if the T/C case is staying in 2WD or if the front axle actuator is not locking.

It could be you push button switch. The switch went out on my 99Z71 and it did the same thing that your truck is doing. I replaced it and it worked fine. Before you go out and buy a new one, see if one of your friends will let you use their. As long as it is the same year I dont see why this shouldnt work.

i hope im not insuting anyone but....are you sure it isnt in 4wd? go into a parking lot and put it in 4wd, then turn the wheels as sharp as you can, go slowly and you should be able to feel resistance and some bucking.

i'm sure. ive tried that. i dont feel what i should. you can hear it shift over to 4 -lo and to 2-hi, but there's no noise for switchin over to 4-hi

If you are ever on the south side of austin, I could scan it for you to see what the problem is.

Sounds Like the TLA Is shot or the button is shot. Jack the truck up On all 4 corners and place it on jack stands and shift to 4 hi then low to see if 4wd works at all!

Tough to make an NP8 go into 4HI with the wheels off the ground. Put it in 4HI then roll a ways before lifting all 4 wheels off the ground and testing it.