Front axle not engaging when button is pushed

COASTN

MEMBER
CHEVROLET S-10

'94 S10 with 140k 4.3 auto with push button, (electronic) 4 wheel engagement. The lights on the button illuminate and the vehicle will go into lo range, but the front axle does not engage in either hi or lo. I see many suggestions to replace the actuator in other questions. Does the actuator have anything to do with the hi/lo range? A local dealership gave 3 possible culprits: electric shift motor (actuator?), Encoder assembly and or the front axle lock switch. New, these items total just under $1000. Is there a way to bench test these componants? Are there other componants that could be responsible? I just purchased it from a dealer so I have no history on it. Thanks for your time and help.

1 Reply

CHEVY22

MECHANIC
1,375 POSTS

If the switch is working properly you should see all ranges light up when the key is turned and you stated the vehicle goes into 4x4 but the front axle wont lock in, as long as the transfer cse is shifting there are only two things it could be the front axle switch or the actuator located in the center lower of the cowl panel, as long a the front axle switch is getting vacuum you can rule that out and check the axle switch which is on the right side of the axle and has a two pin connector and cost 12 bucks, you can check it for an open, hope this helps

jim