jplante4 wrote:
Ok, there are a couple of things that can go on with an Allison.
Firstly, the mode on mode usually delays the downshift on hills until about 1500 RPM. It prevents the constant shifting when doing the rolling hills. If you're a driver, you already speed up in anticipation of hills anyway so you probably don't notice this. On my Allison, I go to mode when I get to the big roads.
If you have an exhaust brake (PAC brake etc), the Allison ECM will select either 4th or second gear on the pre-select and will downshift to the pre-selected gear when RPM allow it as soon as you start braking. Once you come off the brake and go back to the accelerator, the Allison will shift to the normal gear for that speed and start upshifting again. Some people drive around with the PAC brake on all the time. I don't like the way it jerks out of the lower gear when you step on the gas, therefore I turn on the PAC brake only when I need to slow down.
My guess is you turned on the PAC brake at some point.
Agree, this is the most likely cause. Turn OFF the exhaust brake to verify. BUT, any throttle should turn off the exhaust brake (and transmission left window should show "6". Could be the throttle position sensor is mis adjusted. You really want to address this, as you MAY also have the exhaust brake active with this happens. That would be very hard on the engine (on throttle AND exhaust brake at the same time).
Wouldn't hurt to check the transmission for diagnostic codes-- easily done from the driver's seat:
Turn on ignition (engine off).
Press the transmission shift pad up and down arrows at the same time. Your coach is right at the break point for adding checking fluid level from the shift pad, so you will see one of the following come up depending on whether you have this feature: OL or d1. If OL, press the up and down arrows again to get to d1. If there is a diagnostic code, it will display as d1, then a two digit code. Record it. If you get a d1 - -, there are no codes. If you do have a d1, press the mode button to go to d2. Continue until you get a d_ - -.
To exit, just turn off the ignition.
Let us know what you find
