I need help! I don't have 4WD on my Daihatsu Hijet because the front axel lock is not coming on. When I press the button on the 4WD shifter, I hear some vacuum sounds under the seat, and the actuator in the rear works, but the front actuator does not actually push out to engage the axel lock. I tested the button and it is good. No green light is coming on on the dash though. I've read that it can be a problem with a switch or something behind the dash? Can anyone tell me exactly where the problem might be? Thank you!