No Auto 4X4 ABS Light on. Speed sensor???

[FireZingr]

OK here is what my symptoms are:

ABS light constant ON. ABS non operational at all, slick road slam the brakes wheels lock up.
Auto 4X4 apparently non operational. Snow covered road in auto mode stomp the gas and rear wheels only spin. Turn to 4 High or 4 Low and all 4 wheels spin.

Now my questions is:

I know that the ABS system uses speed sensors to determine speed/wheel lock-up but does the auto 4X4 system also use the speed sensors to determine when and if to lock the 4X4 in auto mode. I have replaced both front wheel bearing hub assemblies so I would assume that the rear speed sensor is probably the culprit. Am I correct in my assumptions??

If it is not sensing real wheel spinning/change in speed from the front wheels then it doesn't know when to lock the auto 4X4 in right??

And the ABS not working at all would also be caused by the sensor not sensing the rear wheels locking up while the front keep turning or the front locking up and the rear keep turning.

 

[gijoecam]

I'd say you're on the right path on all counts, but it's a guessing game at best without knowing exactly what code it's got stored. I'd give the rear sensor a shot. It's a common failure item, and if it's not the problem, it's only a $15 part (or less) so it's not a lot of extra dough.

-Joe

 

[FireZingr]

Anyone else have any ideas?