2000 GMC K3500 4X4 engangement issue.

[biggman100]

I recently purchased a 2000 GMC K3500 4X4, auto, 5.7, short cab, that has an issue with the 4 wheel drive not engaging. I first thought it might be the actuator, but, after further inspection, i found that no power is going to the actuator at all. The 4 wheel drive is engaged by a lever on the floor, not a button on the dash. I have checked all the fuses, and unless i missed something, i dont see any that are blown. I dont have the manual for the truck, and i cant seem to find out if there are any relays, or even which fuses, are for the 4 wheel drive system, so, my first question is, does anyone know which fuses or relays i would specifically look for, and where they might be located? Any diagrams you can post, or point me to, would be greatly appreciated. Next question, because it is lever actuated, and not button actuated, would it still have the control unit, that i cant remember the name of, that the electronic systems have on the transfer case, and, if so, where would it be located? I cant seem to find anything on the transfer case that looks like what i found for pics of that part online.

 

My other issue with it is unrelated to the transfer case, but, the PO installed an aftermarket cold air intake, that i had all kinds of issues with, due to air leaks at all the clamps, the filter laying against the exahaust, and basically very poor installation. My question there is, which would be the better option, as i bought the truck to use mainly as a plow vehicle, so, would it be better to find the original air box and plumbing, and install that, or, does the cold air intake really make a difference in power and fuel economy on these trucks?

 

Thank you in advance for any help you guys can give me with this.

[biggman100]

I may have fixed the 4 wheel drive issue myself, but, im lost on what might have caused it to happen in the first place. I found the diagram for the fuse box, figured out which fuse is for the 4wd, replaced it, and now the 4 wheel drive light works, and there is power at the actuator, so, it seems the fuse was the issue, but, my question is, what caused it to blow in the first place. Would driving it at highway speeds in 4hi cause the fuse to blow? Or, would something else be the more logical reason?

[Moses Ludel]

More like wiring or a short, biggman100...As you well know, anything that raises resistance, in 12VDC that means on the positive or ground side, will blow a fuse.  If the new fuse blows, run a resistance check or a check for insulation resistance and short(s) to ground...

 

Moses