I have a 2001 GMC Sierra 1500HD with the 5.3 in it.

The first problem.

My tow/haul mode button on the shifter handle doesn't work. No light comes on, and the truck doesn't shift down, or rev higher between gears. Where is a good place to start trouble shooting?

And another problem. The dash lights in my headlight switch, and in my heater switch control don't work. Good place to start trouble shooting that?

Thanks

 

Your Tow/Mode button. I would start with the fuses

Your headlight and Heater light is a simple bulb replacement.

 

I have already checked those, everything is fine, including the relays.

 

tow haul inop from broken wires in column usually at base of shift lever. Heater switch wont work? No hot/cold? blower? vents? or lights? Headlamp switch could just be the switch?

 

Everything works fine. Just the illumination lights don't come on.

 

The bulbs are probably burnt out. I think they are soldered to the circuit boards.

 

I think the little bulbs are burnt too.
When my fog light SWITCH BULB burnt out I had to solder a new bulb after I figured out how to get to it

 

Mine has the little snap in bulbs. I have already changed them.

 

U da man

 

but it didn't fix anything :/