In 4WD or not?

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MassHoe04

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When I lift one front wheel off the ground at a time with the engine off and transmission in Park and the wheel can still spin freely by hand (not locked up)... It is definitely in 2WD.

Am I right in thinking that there is no possible way it could be in 4WD, if I can spin the one tire that is off the ground?

Could be just hypochondria, but push button indicator lights respond and stay solid when hitting the 2H and 4H buttons back and forth.
Just feels and sounds "different" than normal.

I am thinking it just feels and sounds like it might be in 4WD, but I don't know how that could be I could be if I can spin the wheels and the transfer case makes a much different noise when it moves into 4H.

I can't jack all four off the ground safely with things running to see if all four wheels turn, so I am stuck with two jack stands and trying one wheel off the ground at a time.

Based on spinning front wheels, can I be sure I am only in 2WD mode?

I could be worrying myself into a frenzy over nothing...
 

Mudsport96

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Im not sure how the front ends work in these things. The old blazers were vacuum actuated so if the engine was off or at wot for long enough the front would unlock. The EARLY K trucks were heated wax rods that expanded like in a thermostat that pushed a lever to engage the axle...if driven into a almost frozen creek the front would unlock ( that was a cold walk). But these i am unsure how the fronts are controlled. It may be that without the engine running it won't lock.
 
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MassHoe04

MassHoe04

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I think it might have been stuck even though indicators said otherwise... I put in transmision in N and shifted transfer in and out of 2H a few time then rolled back, put in drive.

Steering feels normal. Much more floaty on the steering wheel like before.

Vibes on slowing at certain speeds and on braking still there. I'll get back to zeroing in on that again. Suspect cv axle as originally thought before sidetracking on stuck 4WD.

Could also be the cheap rotors I put on the front last year too.
 

rockola1971

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Im not sure how the front ends work in these things. The old blazers were vacuum actuated so if the engine was off or at wot for long enough the front would unlock. The EARLY K trucks were heated wax rods that expanded like in a thermostat that pushed a lever to engage the axle...if driven into a almost frozen creek the front would unlock ( that was a cold walk). But these i am unsure how the fronts are controlled. It may be that without the engine running it won't lock.
Our chassis series is very similar to the old school vacuum actuator on the front diff but instead ours has an electric actuator but it is in the same place as the old school ones were.
 

Fless

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Your Tech 2 will tell you if the front diff actuator is commanded on or off. It can be removed from the diff and let hang down; verify physical operation by observing what it does with your dash switch commands between 2wd and 4wd (or as commanded with the Tech 2).

Some get lazy and take longer than a second to engage; time to change any that do that.
 
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MassHoe04

MassHoe04

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Whether the feeling the front end was in 4WD was real or imagined, I am definitely in 2WD mode now.

I think the rumble/grumble I still hear and feel when slowing and braking from certain speeds is one of the CV axles. I may remove them on my next day off (next Friday) to confirm that theory.
If it goes away, I'll definitely be replacing the CV axles in the next few weeks.
 

SnowDrifter

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A quick note about 4wd in our vehicles:
The front end is disconnected twice. Once from the transfer case, and once again inside the front differential.
In 2wd, you can just grab the front drive shaft and spin it with the vehicle in park and on the ground.

That also means you can tell from a quick glance which piece of the system is causing trouble. If you place the vehicle in 4hi (not 4 auto) and lift one front wheel off the ground, spinning the wheel will tell you everything. A spinning wheel with the driveshaft not-moving means the front actuator isn't triggering. A spinning driveshaft means something is up with the transfer case

Regarding the growling:
Be cautious removing the cv axles. The front nubs that go through the center of your wheel bearing are also responsible for holding your wheel bearing together. That is to say, don't drive the thing if you take the whole axle out because your front wheel will probably pass you on the freeway.
I'd also be very suspicious if the growling is from the CV axles. They're straight at ride height, and unloaded in 2wd. Nothing there to make noise. Toss your trans in neutral on slowdown to take load off the rear diff. Look at your wheel bearings and brake rotor surface.
 

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