Lockers, Not getting Air!

IIRC,the hot wire goes to a solenoid that sends the air to the locker...
I think that's where the problem will be....

 

X2....

... Philip

 

In vest in a $10.00 DVOM (mater) and check where the power stops... and verify the 12vdc is arriving at solenoid/or not..

 

Your truck is controlled by a body controller computer. Troubleshooting is a bit more complicated. The dash switch is only a digital input to the body controller. The body controller will then turn on the solenoid for the diff lock. On the left hand frame rail, usually near the rear of trans, is the air solenoid pack. Depending on how your truck was spec'd you could have several solenoids, or just 1 or 2. Air suspension and air horn are typical accessories that will also be included in this pack. The way it works is, the main board has about 4 sockets for air solenoid blocks to plug into. All the blocks get a common source of air from the tanks. The solenoid board is supplied with 12 volts constantly, and the body controller closes the ground circuit to actuate that particular solenoid. The air line to your diff lock should be a unique colour. Follow it the best you can to locate the board. From the factory each solenoid block does have a sticker on that says what it is for. Hopefully they are still legible. Once you find your board, hopefully there are other solenoids also in it, such as and air horn. Basically if the air horn function works, you know the board is getting power. If the diff lock is the only solenoid on that board, you will see a 5 wire connector. Unplug it and power should be on one of the pins, (key must be on). If you have power, then either the ground wire back to the body controller is open somewhere, or the solenoid block itself has failed.