2002 Chevy Astro All wheel drive

DFRIESEN

MEMBER
2002 CHEVROLET ASTRO
6 CYL
4WD
AUTOMATIC
225,000 MILES

The van appears to be in 4 wheel drive all the time. When I turn a sharp corner, the back wheels seem to lock up, that is, they both turn at the same rate, as though there is no differential. When the front wheel drive shaft is removed, this does not happen.

I have replaced the transfer case and the motor attached to it. Nothing changes.

4 Replies

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Hi:
Is the vehicle full time 4wd, or do you have the option between 2 and 4wd?

My first question would deal with the rear differential. There are clutches inside it that allow for the limited slip to function and prevent exactly what you have described. If you lift both rear wheels off the ground and spin one of the wheels, does the other one spin in the same direction or the opposite?

Let me know.

Joe

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Tuesday, December 16th, 2008 AT 5:35 PM

DFRIESEN

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3 POSTS

Thanx for the reply.

This is a safari van all wheel drive.
The front wheels are in neutral until the back wheels turn a fraction faster than the front wheels. This happens automatically. Or is supposed to.

When the drive shaft to the front wheels is diconnected, the diff acts as normal. When the front drive shaft is connected, the van remains in 4 wheel drive all the time. This should not as per above paragraph.

I suspect that the problem is electrical or electronic but don't know where to start looking. Neither does anyone in Winnipeg, Canada.

Any idea's?

Thanx

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Sunday, December 28th, 2008 AT 9:12 PM

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

I hate to say it, but I'm not sure. I do know that the automatic 4wd is engaged by the computer. Are the tires all the same size on the vehicle? Smaller ones on the front or back would trick the computer into thinking they are at different speeds. I read that you had people look at it. Has a dealer checked it?

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Monday, December 29th, 2008 AT 12:44 AM

DFRIESEN

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3 POSTS

Hi

This is what I've done so far. Put all new tires on all 4 wheels at the same time. Replaced the transfer case and the motor that activates it. Replaced every movable part in the diff. The diff works fine if the front drive shaft is removed. Does not work as it should as soon as it's re-connected.

Hate to go to a dealer ship because I know that will be big bucks but may have to resort to that.

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Monday, December 29th, 2008 AT 6:19 AM