Chevy & GMC Vans

No I think that would burn out the motor.

A possibility could be a pulse switch that you hold down for short intervals, but there's almost no point. The AWD works great all on its own.

Why would it burn out the motor?

The encoder motor isn't an ordinary motor like in a cordless drill. It's not driven by steady current.

Your transfer case isn't part-time 4WD. It's an active on-demand unit, that automatically sends just the right amount of power, at the right time, to the front wheels through a clutch. The clutch is actuated by the encoder motor, but a simple on/off switch is not precise enough to deliver little bits of torque. Instead, the motor is regulated by the transfer case control module (TCCM) which sends a pulse width modulated (PWM) signal thousands of times per second (think ABS). Putting a steady current to the encoder motor would be like pulling the trigger on your cordless and then stopping it from turning.

More sophisticated transfer cases like the NV236 do allow you to switch to 4WD. To do this, the encoder motor closes the clutch and then locks. Current to the motor can then be turned off.

OK, well, that is quite interesting.

Hmmm....

Imagine my surprise that this thread was still going
Thanks timelessbeing for digging up such great info!

john

I'm a science geek. It's what I do.

It snowed a bit up here in Columbus, Montana-about four inches or so. The snow is light and fluffy-easy for 2wd truck to get around in. So, not a big challenge. But still, I had to take the van out and play with it.

One thing that I need to get used to is the use of the gas pedal. Since the AWD engages only when the rear wheels are traveling faster than the front wheels, if I get into a front end push, I need to give it just a bit of gas to bring the front end around. I think that is about the only time my 4runner has an advantage-and it has low range.

For running around, hitting the occasional road or showing people what this van can do-it's perfect.

What I do want is an "off" switch so I can do cookies in the parking lot. Sounds cheesy but hey-what is an all wheel drive van for if not to do donuts?

I did do donuts with the AWD and it was weird. The front end would push-then not push. Very unpredictable compared to a full time case which would allow one to skate around.

All in all, AWD with the help of a computer is far more preferred than a 4wd case when it comes to ice and snow for me and my wife.

I've had a lot of success doing doughnuts with the AWD on. I can get it to spin around on one spot like a top! It sounds like your AWD may need some maintenance. It shouldn't lag or be inconsistent like that. When's the last time the TC fluid was changed?

But if you do want to turn it off, like if you have to mount a different size spare, just yank the ATC mini fuse from under the hood.

Well, I didn't have the wheels turned until after I was moving forward. The fluid was changed regularly and on schedule.

On my 4runner, it has a locking rear axle which-well, you know what can happen then.

timelessbeing wrote:No I think that would burn out the motor.

A possibility could be a pulse switch that you hold down for short intervals, but there's almost no point. The AWD works great all on its own.

I have thought about picking up an encoder motor and putting 20 amps to it. Seems to be a good test. I wonder how long it would last?

Ultimately, the heat has to go somewhere. I wonder what would heat up first?

The motor will probably spin away. But sitting in the transfer case it will stop when the clutch is at 95%. If you really want 4WD, I think you'll need another TC.

What I don't want is to lose my clutches if I am cruising up a long snowy/muddy hill. Is there a danger of that?

I don't think I understand your question. Can you elaborate?

i think he means he doesn't want the computer to burn them out.

OK I think I get it.

If you're going through a lot of very slippery stuff, and the clutch is constantly being feathered, I suppose the clutch lining will be eaten up quicker. It will be evident because the blue fluid will come out black. If you get into a lot of situations like that, I would be considering better tires or chains. Or going somewhere else.