99 Yukon Auto-trac switch lights

[linust]

Most of the time, on startup, I get the correct flash of all four lights. Normal driving '2-Hi' light is on. For most of my around-town driving, all seems fine.

 

If I'm on the open road for awhile (say 30+ minutes) the 2-Hi light goes out...and none of the other lights are on. In this case, pressing on the 2-Hi or Auto buttons sometimes brings a light back on, sometimes not. If a light does come back on, it typically goes back out in a minute or two.

 

Sometimes, on startup, none of the switch lights flash, and none of them stay lit while driving.

 

I know the NP-246/Auto-trac system has a lot of self-diagnostics, but I don't have a scan tool for this car (yet). Any ideas here? Is this as simple as a faulty switch or something more serious?

 

Thanks!

[GM-Tech]

We've had some switch issues and programming issues, but not in '99 that I'm aware of. Need to have some diagnosis done on it and see if there are any DTC's related to the ATC.