The 4wd has stopped working and service 4 light is on its a 4 button system that i believe rhe electro vaccine solenoid in the cowl has died as long as i bypass it and send vacuum directly to the front axle it indicates 4hi and 4 lo respectively any way to test this switch?

 

Sorry i got in a hurry earlier but its a 99jimmy slt that I working on

 

The post is very hard to understand with no puncuation. Some words appear to be spelled wrong as well. Could you possibly edit it so it's easier to understand?

 

Sorry for the lack of punctuation in the previous post I am working on a 99gmc jimmy 4x4 slt trim with 4 button 4wd system. It recently started misbehaving in that it won't ever complete the shift of the front axle when commanded to. I have found that if i bypass the electric vacuum solenoid and hook the actuator directly to vacuum it works fine for 4 hi and 4lo.so that kind of rules out the encoder motor on the t/c just wondering if there's any way to test this solenoid before I order a new one

 

Sure there is. It has two contact pins. If You apply 12V DC to the valve coil, it should get open. Try blowing the connector peg and see if the air flows though when You apply the power.

 

Give the solenoid a smack ...I have unstuck them this way