Just wanted to offer this fix for anyone else whose been frustrated with the random lights, operation and "service 4-wheel drive" message on their silverado. I have a 2000 silverado 1500 and have been putting up with a lot of randomness in my 4wd indicators for about 2 years. The past few months it has started to actually affect the mechanical shifting into/out of 4wd so I figured I couldn't put it off any longer. I've heard horror stories of high repair bills ($900 to $1500) which only sometimes or only temporarily fixed the problem. I've noticed that hot and cold, bumps, and out of frustration... hitting the dash would sometimes "fix" the indicator lights. After reading a post online about a loose wire, I thought it would be worth it to check it out since I'd have to tear it apart to replace it anyhow...

Here's the fix:
remove the trim piece from the dash face (just spring clips on there)
pull out the control board (pry with screwdriver on top and left side)
unplug both wire harnesses
pop open the box (3 plastic prongs on each side of the box)

carefully check the connections on the circuit board opposite to where the plugs connect

solder as needed (I had 4 cracked solder connections at the lower plug site)

put it back together and you just saved $80-100 bucks on the part

Not to mention the damage that the random on/off signals will eventually cause your mechanical components.

 

bump.