1993 Chevy S-10 Transfer case

1993 CHEVROLET S-10
185,000 MILES • 6 CYL • 4WD • AUTOMATIC
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SCOTT56308
  • MEMBER
  • 3 POSTS
I have the NP233 transfer case and I was wondering
if there is a way to test the vacuum actuator,motor or the control module, It sounds like the motor is switching
when I push the button but its not in four wheel drive.
Dec 5, 2009 at 8:48 PM
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SWILLIAMS
  • CERTIFIED EXPERT
  • 597 POSTS
Well the actuator is on the inner fender with a cable down to the front axle.
The Control module is behind the passenger kick panel.
The actuator motor is on the side of the transfer case.
However the common failure is the vacuum switch located on the transfer case. It isn't hard to replace. It just screws into the case.

Easy way to determine where the problem is. Jack up either of the front wheels. NOT BOTH. Now with it in 2WD you should be able to rotate that tire. Now switch into 4X4 and try it again. If it is engaging you shouldn't be able to move the tire. Now apply a vacuum to the actuator and try again. If it still turns the problem is probably in the transfer case. If it doesn't turn the problem is likely the switch.
Dec 5, 2009 at 10:08 PM