The das 4x4 switch has been replaced once and needs another. The indicator flashes on everthing except 2 wheel drive. However it does lock into 4x4. Is the better switch out there somewhere?

is your Z71 a Silverado (new body style in 1999)? If it is, it's likely not the switch.

If you have the 4 button switch with the round AWD button, you most likely need the actuator position sensor replaced. It's quite common for those to fail by rubbing through the resistive coating on the ring, thus causng a voltage error and throwing a switch code. There's also a programming update available.

Don't program it without replacing the sensor.

Where is that sensor located? The repair garage advised it was the switch the first time it this happened. I have not gotten it diagnosed other than this forum this time. What do you mean programmed? I do have the 4 button type.

First, shift the transfer case into neutral and set the parking brake.

There's an actuator assembly bolted to the side of the transfer case, above the front drive shaft. It uses 3 15.. bolts to hold it on. You'll need to remove the front drive shaft to take it off. There's a harness plugged into the actuator. Be sure to disconnect it.

After you remove the actuator assembly, there's 4 screws (2 different size torx, 2 ea. #15 and 2 ea. #20 IIRC), then the end with the long plastic cover slides off. There's a big gear in there with a little dot on it (embossed). Make sure you note the position of this dot. It's very important to put it back in the same position. The gear slides up and out, disconnect the 3-wire connector on the back and look at the back side of the gear. That big round black thing is the sensor. It pops off with a flat bladed screwdriver. Pop the new sensor on in place of the old one. Reconnect the 3-wire connector to the new sensor, making sure to put the connector on the right way (it ]is possible to put it on wrong. Reinstall the gear, making sure to line the dot in the same place it was before you started. Replace the orange gasket around the perimeter of the actuator assembly, reassemble and reinstall. Use a zip-tie to replace the boot retainer ring on the drive line. Start the engine and shift the transmission back into neutral. Shift through all the transfer case selections, then back to 2wd. Drive happy.

Make sure you take it to the dealership for TCCM reprogramming. That's the part of this repair that makes it permanent.

The chevrolet place stated they did not sell the parts seperatly it was sold has one unit. I called two different dealerships.

If I remember, I'll call tomorrow and get the part numbers.

I replaced the whole encoder today. The same thing is going on. The little lite in the dash switch to flashes when you change it from 2whl to 4whl high or 4whl low or auto 4x4. The message center does not show anything. When a computer is hooked up there are no codes. It is only in the switch on the dash. I also replaced that switch, but same problem. Should the lite be constant in other than 2whl?

It is supposed to flash when transitioning between modes. If it flashes when changing modes, then stays on solid in whatever mode you chose, it's working properly.

It continues to flash until I return it to 2whl. It used to flash only during transition period then illuminate solid while engaged.

Evidently things are worse at the Chevy dealership I worked at than when I left. They are no longer open weekends.

You're probably going to need a Tech2 in order to scan the TCCM. It's separate from the PCM, so simply doing an engine scan won't bring up any code. You should head for the dealership on this one.