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Topic: Dura max won’t downshift  (Read 861 times) previous topic - next topic
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Dura max won’t downshift

Yahoo Message Number: 16771
My 2005 C5500 Duramax won't downshift when pressing the pedal all the way, shifts fine for all other conditions. Any body else have this happen?

Re: [SuperCrvgroup] Dura max won’t downshift

Reply #1 –
Yahoo Message Number: 16772
I've noticed the same. It wasn't the case originally after I bought the rig about 18 months ago.

However, this problem only happens at speeds above 40 mph. It will downshift on a hill at slower speeds. The problem is most apparent on the highway on mountain passes where I'd rather be in a lower gear doing 45 mph rather than dropping below 40 before the downshift happens. But flooring it won't make that happen so I manually do it with the shifter on the steering column.

I was thinking this was a vacuum hose problem and was planning on talking to my mechanic next time I get her serviced. Most of the C5500s he works on are Top kicks with a lot more miles than most RVs so I am hopeful it's a common fix. He did tell me previously that the Allison is "bulletproof" and he never sees any issues before 300K...


Re: [SuperCrvgroup] Dura max won’t downshift

Reply #2 –
Yahoo Message Number: 16782
Sometimes it simply takes a minute to pull over and turn everything off and reset. It's really the first thing to do when something unusual concerning driveability happens.

 

Re: [SuperCrvgroup] Dura max won’t downshift

Reply #3 –
Yahoo Message Number: 16784
It went back to normal the next day. Hoping it doesn't re-occur.... Thanks for replying.