ISX 870 jake brake issue

[Chamberpains]

Your within spec's. I pulled that screen grab from Cummins quickserve. Its FREE! Make an account and Register your ESN (engine serial number).

The info to troubleshoot it is under Service; Manuals; Service Manuals; Signature,ISX,QSX15 Services manuals; Section 20 Vehicle Braking Group 20.

After that, follow everything step by step to ensure things are good and possibly find your problem. If you run down everything and still have a problem, come on back, let us know what you did and we'll go from there.