1993 Exploder - 4x4 Engaging weird.

[94Sierra4x4]

Hey there just picked this thing up a few days ago.
Anyways it's a '93 Exploder XLT Limited, 4-door 4x4, 436k on the body, newer motor/tranny unsure of actual kms. Got it cheap to say the least.

Anyways, a description of my 4x4 issues. Haven't had a chance to actually test in offroad conditions to see if all 4 are spinning, nor have i had it up on stands to spin the tires.

Cruising at 50km/h, into 4x4 high, both the dash and the little light beside button come on.
I hit the 4x4 High dash button at a stop, I hear the relay making its clicks etc. No dash lights.
4x4 Lo, in neutral, foot on brake, no engagement, no relay clicks (that i could hear) no lights, no nothing!

The explorer actually rolls aswell while in park. Read something on the sunvisor that it could be a transfer case problem with not engaging?

I read the troubleshooting guides already but can't seem to come up with a diagnosis. Thanks for the help

 

[Anime]

Welcome to the forums.

First thing I'd suggest is not engaging 4WD on pavement. Ever. You will break the system if you do so. The axles are geared such that the front end "pulls" the rear, and so the front wheels need to be on loose ground (dirt, rock, sand, etc.) so the wheels can slip to make up for this. If you engage the 4WD on pavement, the wheels can't slip, the 4WD system winds up, and something is going to break - and it won't be cheap to fix.

It sounds like the system is engaging normally if you engage it on the fly and the lights come on, and go off when you hit the switch again.

You need to have 4WD Hi engaged before you can engage low range.

After 4WD Hi is engaged, you hit the "Low Range" switch and the lights for that should come on. Sometimes you will need to drive a few feet or so in 4WD Hi before you will be able to use low range.

If there's ever an issue with the system engaging or not, it's usually the 4WD module with the relays you hear clicking, or the transfer case motor. There are threads on fixing both of those.

If it rolls in park then the parking brake pin might be broken, or it could be another transmission/transfer case issue. Likely something internal.