stuck in 4wheel

It's an 84' GMC S15 Jimmy.The 4wd lever wont stay in the 4hi position. The vibrations of driving cause the lever to slowly move back to the 2 wheel position. However, it feels like it is still in 4 hi.
any advice? thanks.

Welcome on your first post on AF.
Craw under there and check the linkage and adjustment on the shift levers and rods to transfer case.
They may be lose or out of adjustment
Are you getting any drive line or transfer case vibration?

It is a remote possibility that one or more of the motor or transmission mounts are bad causing the transfer case to move in relation to the floorboard/shift lever. This could cause the connecting rod to push or pull as you accelerate.

James

I pulled the apart the boot that surrounds the 4wd shift lever. It seems there is a small piece of plastic connected to the lever that is supposed to spring up into position to keep the lever in 2wd. It aint springing. I was wondering if this might explain my problem? It feels smooth while driving other than the resistence when I turn the wheel pretty far which I chalked up to damage from driving it in 4wheel on dry pavment. Everything else is real smooth. It fealt like a problem with the shifter to me, let me know what you think. Thanks

I pulled the apart the boot that surrounds the 4wd shift lever. It seems there is a small piece of plastic connected to the lever that is supposed to spring up into position to keep the lever in 2wd. It aint springing. I was wondering if this might explain my problem? It feels smooth while driving other than the resistence when I turn the wheel pretty far which I chalked up to damage from driving it in 4wheel on dry pavment. Everything else is real smooth. It fealt like a problem with the shifter to me, let me know what you think. Thanks

Not real sure what the plastic is unless it is a shift lever bushing.
But check transfer case shift arms to see if they are is locking in good.
They should like snap it to place or each gear.
MT

Today after a little research I found that the Plastic "switch" that runs next to a similar metal bracket, which has vertical indentations for each lever posistion is cracked. I also noticed what seemed to be the absence of a gauge pin. This site is extremley helpful, I really appreciate all the help.

The shift linkage to the transfer case was lying on top of the skid plate. Amazing I hadn't lost it because I was driving with the linkage there for a few weeks. I hooked it back up it was a lose fit but I got it out of 4WD which is the important thing. This site is an amazing resource, I wanted to thank everyone who gave me advice. Keep up the good work.

You are welcome and thanks for posting back how it went.
Glad you found the problem.
MT