1996 Gmc Front Axle Actuator

[alwinj]

Does anyone have info on how to troubleshoot a thermal front axle actuator on a 1996 GMC truck?

 

Thanks

[BigAssSuburban]

Does anyone have info on how to troubleshoot a thermal front axle actuator on a 1996 GMC truck

 

I have a 97 Sub and currently experiencing problems with 4x4 engaging and it seems to be up front. I removed the Front Differential Actuator (Thermal Type) and tested it by attempting to engage the 4x4 with the engine off to see if the unit would extend. I also disconnected and removed the actuator and bench tested it with a 12v power source as well and was able to determine the problem was not my actuator.