2004 Silverado 2500HD 6.6 litre Duramax What fluid, and how much to change the transfer case fluid? The truck is automatic (Allison Transmission) and has push button 4WD. Also, I am going to change the transmission fluid and spin on filter, is there another filter inside the tranny sump?

SOURCE: Duramax Shuts off at 1000 rpms

I had the same problem and it ended up being the EGR Valve that was sticking.

SOURCE: 01 duramax allison changed fluid and filters now in limp mode

Make sure you have the proper amount of tranny fluild in it and get that Valvoline fluid out of it. Allison transmissons have there own type of tranny fluid and you want to use it. You can buy the right stuff from a Allison dealer. Most Detroit Diesel dealers are also Allison dealers. Look them up in your phone book and they will tell you the quanity and sell you five gallon pails of the fluid. Just get the serial number off of the side of the transmisson before you call. Change the fliters again too. Believe me, this is important. My company has Yard horses with Allison transmissions and you don't want to screw with the small stuff. Service them right and they work as hard as you want.

SOURCE: location of speed sensor 2001chevy silverado 3500

above were your electrical plugin plugs up on the rear left of transmission. that is your output shaft speed sensor.

SOURCE: rpm gauge, speedometer, & other gauges

This model always this problem, usually after about 90,000 miles and the other instruments will eventually follow. There are companies that will repair this for you just use google (instrumentclusters.com) to find them. I was charged 185.00 for the repair... GM wanted over 500.00!

SOURCE: Left front wheel clicking. think wheel bearing.

Clicking, especially while turning usually more so points to a problem with the CV joint, or axel, the easiest way to test a wheel baring is to jack up that side of the truck until the tire is off the ground, leave the lug nuts on and try to wobble the tire in all directions, if everything seems solid it is not likely the bearing casuse the sound, another note when a bearing starts to go bad, it usually hums opposed to clicks. Im sorry i dont have a diagram, but this proceedure should get you on the right track in diagnosing the issure, good luck!!