[Hal Brodmann]

No 4WD on my 2004 Z85 LS. When I press the button, it flashes a few times and then stays lit on 4HI and 4LO, but the front driveshaft does not turn. Most problems I've read about here are the lights flash, but then go back to 2WD. Mine lights up like it's working, but it doesn't. I've never owned a 4WD before, so I'm lost. I hate to just start replacing parts, since they are a bit $$. Can someone please provide a step-by-step diagnosis process that will allow me to narrow down what part might be the problem? I have volt meters and know how to use them, but have no idea where to start and what to look for.
I appreciate any help that you can supply!

 

[Savet]

If you don't get the answer on here, I would look for a digital copy of the service manual. It will provide the diagnostic steps.

 

[Hal Brodmann]

Actually, no. I got now answers here, so I purchased a Haynes manual from my local Autozone. Thar was a real waste of money. I've used their manuals in the past, but the 4WD section didn't have a single picture, no diagnostic information, but only instructions on how to remove and replace the individual components, with now real description of where the parts were located, what they looked like, or what the symptoms would be if the part was defective. as far as any internal repairs to the transfer case, it was recommended that you take it somewhere to have it rebuilt, or purchase a rebuilt unit and replace it yourself. Very limited instructions on how to remove and replace, and again - not a single picture.

 

[Savet]

Sorry, that sucks. Out of curiosity, how are you confirming that you are not getting 4wd? If you follow the instructions to shift the transmission into neutral, does the truck go into neutral? If so, do you see any improvement going from neutral to 4wd? When you shift, are you traveling at a low speed (5-10mph)?

I understand your frustration. A friend of mine rebuilt the rear of his late model Silverado with a rebuilt unit and encountered similar frustrations. It's easy to get 100 different opinions on the best bed cover, but people doing this level of work on their trucks are really hard to find.

You might also try one of the more specialized subreddits on Reddit as you might be able to target your question at people who do auto repair and have familiarity with these systems.