Pac Brake pops out of second gear for an instant

Question

We have a Monaco dynasty 1998 with An Allison world transmission and  pac brake. About a month ago,  the pac brake  failed.  we thought it was the pedal but when I took it in to Freightliner, it was a relay they replaced. it worked fine on the flats, but on vacation now, on the big hills,  we've noticed  the pad brake pops out when activated. it'll drop down to second gear right away and then it'll pop out and release the paycheck brake, and go back and pop out over and over again.  The transmission indicator shows it flipping from 2 to 6 back to 2 to 6. other than that,  it works fine I'm wondering what might be causing that little glitch.  it's almost as if I'm going too fast for the gear but I've slowed down and it still will blip out back and forth.   Thank you

wolfe10 · Answer

No if you were in danger of overspeeding, the Allison shift pad would NOT go back to 6th.

You have an electrical problem between before the Allison ECM. Fuse sounds like it is still good as it does work at times. Switch may be an issue, relay may be an issue, connection to Allison ECM may be an issue.

mandalay_parr · Answer

wolfe10 wrote:No if you were in danger of overspeeding, the Allison shift pad would NOT go back to 6th.You have an electrical problem between before the Allison ECM.  Fuse sounds like it is still good as it does work at times. Switch may be an issue, relay may be an issue, connection to Allison ECM may be an issue.X2

11178adm · Answer

you may have a ecm programing issue if the minimum engine brake speed is set too high it will disengage at the speed it is set at and then reengage when the coach speeds back up. this parameter can be checked and reset at any cummins shop

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Pac Brake pops out of second gear for an instant

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