99 gmc 1500 pick up 4x4

try the bulb, or could just be a bad earth connection at the lamp unit, I hope this helps

The wires are probably broken. They follow the shifter down into the steering column. After many years of shifting the wires break. You can find the wires inside the rubber piece that surrounds the gear shifter. They're orange. You can splice them and put them back in.

could be the switch or modual.check wiring for worn through or earthing.

This is only an idea-pull column shifter boot-you will notice a ORANGE wrapped wire which runs from the button on the shifter down toward the steering column. This is the Tow/haul wire. The way this is positioned on the steering column will cause the wire to be pinched when ever the steering wheel is adjusted. This pinching can cause a short or cause the tow/haul not to work at all. NOTE: Inside this orange wire wrap are two very fine fiber wires. Be careful and good luck

There is a 3/4 clutch pack in the trans that when it fails you loose those two gears. There is nothing you can do other than to pull the trans and do an overhaul . I started rebuilding those back in 1982 when they first came out in the old 700r4. Even though the new 4L60E is all computer controlled, it is still doing the same thing.

If you tow with it and do not push the tow/haul button it will burn the clutches, especially if you are towing a large heavy load.

Sorry for the bad news

You are talking about the trailer option button on the end of the shift select lever ?
I would say a fuse, check there first, and there is also a relay.
As far as I can tell all this switch does is take the tranny out of overdrive, which you can do with shift lever manualy.
If you do not find the problem, you may have to replace the switch.

 u can get it from google.com

I had a problem with my tow/haul button not working. I came to find out that the gear shift had cut the wire running to the button in two. You may want to check that.

tow in tow/haul and use 4x4 when necessary..it is how the truck is designed ..... :) have a good day

Hi, the problem is when you are tilting the steering wheel all the way up it's putting to much tenstion on the wires that come outof your shifter that run to the tow/haul button. i am 99% sure your wires are disconected. rewire them and add some extra wire so next time there will be more slack in your wires.