Did the lights ever come on before?

Also, what exactly do you do when you try to engage it in 4lo?

 

yes the lights did come on and as for 4 low i put it in N first

 

From what it seems, Dodge has been a hit and miss with the working 4x4 light. I've had two different NV231 transfercase in my truck, and one light up and the other didn't. I'm pretty sure it's the little switch inside that detecs whether or not it's in. If that's replaced, the light should work again.

 

Yellow....I don't know which Trans case I have (I can chose 2 wheel or 4 lock), but my light does not work....tell me more if you can.

 

What year is your truck? I assume it's an 02 by your screen name.

If it's a 2000 or older, there's a little electronic detector which senses when the shifter fork has been engaged in 4wd or not. If you're is, then it should just be that.

If it's a 2001+ then I'm not sure. I'm not familiar with those transfercases or types of actuators. It could be within the actuators, or actually have a seperate detector.

It seems as this is a VERY common problem with this platform, and should be addressed to Diamler-Chrysler.