How Should The 4wd Operate?

sahls01gmc · February 24, 2011

I still seem to be having some issues with the 4WD on my truck. When I had the truck jacked up off the ground and ran it through the 4WD options, it performed fine. I had a few snags were the front wouldn't engage until I momentarily went in reverse, but then acted normally. Same goes for shifting into 2WD from hi or lo, sometimes I had to "back up" for a sec, then it would correctly. I have the Auto shift 4WD on the dash.

My question is, how is it supposed to work when the truck is not in the air? I went to a field to check the 4WD options again, but I couldn't get the same results as I did when it was in the air. I never noticed the 4WD fully engaging. I could hear the motor shifting into Auto, 2hi, 4hi, and 4lo just fine, but I couldn't seem to get the front to engage. Not even when I backed up.

Could I still be having a problem with my front axle 4WD actuator? Like I stated, it works in the air, but not on the ground (at least I can't get the wheels to spin with the back ones under power). Or am I in for something for worse (more expensive) like the front axle?

Any help is greatly appreciated!

James

gmtech4 · February 25, 2011

james ....

the driveline does NOT like and cant shift properly in the stopped position,....

the truck has to be in neutral rolling slightly ....they shift awesome everytime,

try that

sahls01gmc · February 25, 2011

I'll give it a try. The reason I switched while parked is because of how the truck reacted while it was in the air. The only time it would engage was when I went backwards.

What is a max speed to switch gears?

James

old-chevy-dude · February 25, 2011

my 2010 shifts fine in Neutral, it won't even engage in Park..

2WD -> 4Hi moving forward in Drive under 5mph or stopped and in Neutral no problem.

2WD -> 4Lo stopped and in Neutral no problem.

2WD -> Neutral, Stopped, on level surface, in neutral no problem.

same going from 4lo, 4hi, N to 2WD.. stopped and in Neutral.

if in Park or Reverse for any of them, no go the computer will not allow it to engage, the light just flashes.

sahls01gmc · February 26, 2011

my 2010 shifts fine in Neutral, it won't even engage in Park..

2WD -> 4Hi moving forward in Drive under 5mph or stopped and in Neutral no problem.

2WD -> 4Lo stopped and in Neutral no problem.

2WD -> Neutral, Stopped, on level surface, in neutral no problem.

same going from 4lo, 4hi, N to 2WD.. stopped and in Neutral.

if in Park or Reverse for any of them, no go the computer will not allow it to engage, the light just flashes.

Is that the recommended procedure for your truck, or your method? That's what I do every time, but I know it fully engages when you go in reverse for a sec.

I'm just wondering how well my 4WD works.....I can't see the front wheels (at least the driver's side) spin when the truck is on the ground, but they did spin when it was in the air.

James

old-chevy-dude · February 26, 2011

It's how the owners manual says to do it. It is possible or more likely that the programming between my 2010 and your 2001 has changed. But mine will not engage in reverse, and I just tried it a few moments ago to be sure. It has to be in neutral for 4pm and neutral. Or moving at very low speed for 4th

gmtech4 · February 26, 2011

stop with the "in the air " stuff james ,you're making me nuts ,,and yourself ....

take it to a tech that knows these trucks well AT A DEALER !!!

good luck

SouthCo · February 26, 2011

It should go in to 4wd (lo or high) and auto awd (if you have it) while stopped or moving forward. you should not have to go in reverse.

sahls01gmc · February 26, 2011

stop with the "in the air " stuff james ,you're making me nuts ,,and yourself ....

take it to a tech that knows these trucks well AT A DEALER !!!

good luck

That's what this forum is for, is it not? I posted in here because it says "Please, only questions you would go to the dealer for". Thought I was doing the right thing.

I thought I could post up my issues and attempt to fix them by asking every member on here.....perhaps maybe 1 of them has had the same issue, and know how to go about fixing this.

I just want to lay out what I've been doing step by step to give the best description for everyone since they can't witness it first hand.

Sorry to inconvenience anyone annoyed by this thread.

And thank you to everyone for providing their input!

James

zaac · March 18, 2011

I've heard that before "go to the dealer". With a little research I can fix my truck as well as any dealer mech who hates his job. So could you. There are some helpful guys over at full size chevy if you're still looking for help.

Diesail · March 18, 2011

my 2010 shifts fine in Neutral, it won't even engage in Park..

2WD -> 4Hi moving forward in Drive under 5mph or stopped and in Neutral no problem.

2WD -> 4Lo stopped and in Neutral no problem.

2WD -> Neutral, Stopped, on level surface, in neutral no problem.

same going from 4lo, 4hi, N to 2WD.. stopped and in Neutral.

if in Park or Reverse for any of them, no go the computer will not allow it to engage, the light just flashes.

This is exactly the way my 2001 worked. If memory serves it said you could shift to 4-lo while in park but even the slights bind would stop it from doing so.