The 4wd switch on the vacuum actuator will not light my dash light. I replaced the switch, but still nothing. If I push the switch in with my fingers, the dash light illuminates. The 4wd is engaging. How can I get it to light up, it just doesn't seem to be moving the plunger on the light switch far enough?

 

I would do vacuum holding tests on the vacuum motor. It may be in the early stages of failure. If the motor leaks it can engage the axles but not move the shaft far enough to actuate the switch.

 

Thanks Seal, that was the problem, installed a new vacuum actuator and now works flawlessly.