AWD clunks and shakes while 4WD smooth?

[SnuffThePunkz]

Hey, had to sum it up in a quick title, but I have a new to me 97 Expy.

I noticed this on the test drive, but didn't give it much thought as I'd eventually get to it. Well I'll be heading through the mountains end of the month so it's time.

Forgive me as this is my first "newer" vehicle, and only ever driven leaf sprung tanks.

When I engage AWD it almost feels like a u-joint is toast and bucking around in the axle housing, or that a wheel is seriously miss-weighted at any speed. However if I engage 4wd the truck runs smooth as butter without any issues.

As far as I can tell the ABS sensor on the passenger front has had the cables cut/ripped and I'm trying to source a new cable vs splicing one together but haven't had any luck so far (Read: Lazy). Does the ABS affect the AWD? Or is something else likely up?

 

[k9education]

The A4WD is designed to engage when the system senses that the vehicle is losing traction, so I would imagine that a non-functional ABS sensor would prevent the system from operating properly.

 

[nsperf]

Yes ABS sensor affect the AWD.

The sensors feed back wheel speed informatio9n to the PCM which then determines if it needs to engage the front drive shaft via an electric clutch mechanism. Faulty or poor operating wheel sensors will give you some very strange fits when in AWD mode.

 

[SnuffThePunkz]

Alright that makes sense I suppose. I'm not used to these fancy new fangled AWD, PCM and functioning ABS sensors... My right foot has generally been responsible for all that with my last truck.

Thanks!

 

[k9education]

Alright that makes sense I suppose. I'm not used to these fancy new fangled AWD, PCM and functioning ABS sensors... My right foot has generally been responsible for all that with my last truck.

Thanks!

Welcome to 1985.