6x6 issue!

[Brushbuster]

Our fire department is having one single issue with our 5 ton m925. The truck will not engage the front wheel drive.
High Range: Truck in neutral and engaging the front drive lock switch on the dash, front drive light comes on, but the truck remains in normal operation. And to include air is purging into the intake piping draining the air tanks primary and secondary.

Low Range: Truck in neutral, Transfer case placed in low, truck place back into to drive, front drive light comes on, but the truck goes into low range but remains in 6X4 status, and air purges back into the intake draining the primary and secondary air tanks.

Has any one else experinced this and what can we can do to fix this? Help ASAP will be greatful.

 

[gimpyrobb]

You need to look at the TMs to see what isn't hooked up. If it drains the air supply, something is venting to atmosphere that shouldn't be. I wish I knew more of the 900 series to help.

 

[Stan Leschert]

Check the air lines. Chock the truck, get into a position where you can safely listen for leaks, and have a helper initiate the engage procedure.