Jagger

So I have a 1999 Silverado 1500 with the manual select NP261 transfer case . Here is the problem. My 4x4 indicator light popped on earlier today while in 2H I was able to shift my transfer from 2H to 4H and back, and it went away for a while, but came back. At first I figured I didn't adjust the linkage correctly after I rebuilt my transfer case, so after playing around with it I went for a drive to check it out, nothing was different.

After a few hours of playing with the transfer case, the light now stays on. My transfer is not shifting or slipping out of 2H into 4H, unless I shift my selector into 4H, because there is no power going to the front axle. The light comes on no matter what range I have the transfer case in, 4H - 2H - N - 4L.

It sounds like an electrical short in the switch or connections, so I cleaned out the connections on the transfer case with no change, but I have to admit I'm not too familiar with Silverados, I just picked this one up a few weeks ago, and shortly after I found this forum.

If anyone has any ideas, that would be great.

mudmaniac

The indicator light is sent power from the front axle. There is an electric actuator and a contact switch that closes when the axle is engaged. Either your front axle is engaging for some reason or the switch may be sticking. Have someone look at the front drive shaft while you move, if the shaft turns the axle is engaged, if not than it is probably the switch.

Jagger

Yeah the front drive shaft is turning. So I'm going to assume that actuator is bad? Or is there something else that I should be looking at?

mudmaniac

I don't think it's the actuator that is the problem. The actuator fails in an open position. You need to remove the 6 bolts that connect the CV shaft flange to the axle flange on the passenger side, then you remove 2 bolts from the support bracket on the end of the axle. Next remove the 5 bolts that connect the axle tube to the differential and carefully remove the axle.

In the diagram above you can see a clutch fork for that rides on the actuator plunger, (this is not the actual diagram for your truck), there is a spring that pushes it back when the 4wd is disengaged, if this spring is broken it would allow the axle to engage but not disengage. The spring is very inexpensive but it sure is a pain to get to. Maybe one of the GM techs can post an actual parts diagram for you, if not I can take a pic of one I have laying around.