Suspension dump switch

[DVT873]

The switch will flash for one of 2 reasons. Either there is a fault, which should throw a code in Diamond Logic, or a condition (interlock) to dump has not been met. Condition not met does not code.
Indicator Flashes Fast (Twice per second) - There is a problem in the switch or corresponding circuit.
Indicator Flashes Slow (Once per second) - This indicates that all the interlocks have not been met to operate the selected feature.

Key switch in Ignition position.
• Dump switch On.
• Vehicle speed less than or equal to 5 MPH (8 KM/H).
• Solenoids A and B have a good status.

When you are in DLB make sure you are in diagnosing mode. The program can be in editing or diagnosing. Look in the far upper right hand corner. Hope that helps. The DLB manuals are a little vague.
This link should take you to the tool site. The current DLB manual should be a free download.

https://navistarservice.snapon.com/Shopp...Number=DLB

This link takes you to the free public bodybuilder website. The circuit diagrams are there

http://bodybuilder.navistar.com/General/Home.Htm
The air solenoids under the cab apply and release air to a port on the leveling valve thru an air line between the solenoids and the valve. First thing to figure out is what the flashes are telling you.