what kind of transmission do I have.

[gmcbuffalo]

I have a 91 xl chasis what type of transmission came with these units?
Greg

[Jon Wehrenberg]

Five speed Allison. I can't remember if it was the 754 or 755.

Good transmissions. Robust.

[gmcbuffalo]

Thanks Jon
One of the short comings of Prevostcar site is that no matter what year you type in you get the same engine and transmission. 60 series.
Greg

[Loc]

Greg

My 91 chassis had an Allison 755HT.

Loc

[gmcbuffalo]

Jon or loc
Is this anything that can be done with the shifter keyboard beside shifting. Like different mode or codes since there is no display?
Greg

[Jon Wehrenberg]

Not that I am aware of. On the "world" transmission there is a lot that can be done, but not on the five speed.

[gmcbuffalo]

Thanks Jon
Greg

[Loc]

Greg,

My 91 chassis had the ATEC (Allison Transmission Electronic Control) system for the transmission. In the utility bay below the driver's seat were two switches for the DDEC and ATEC. If you switch the ATEC switch you could read any codes by turning the ignition key to the on position and reading the light pulses in the transmission light on the dash board. My Prevost manual had a key code to decipher the light pulses. There was no economy versus power mode setting like the newer 6-speed World Transmissions nor was there a way to check the fluid level through the key pad. I asked the folks at Stewart & Stevenson if there was a reader for the ATEC like can be used for the DDEC. They told me no. I only had one problem with my transmission in 120k miles (five years). The speed sensor went out and it resulted in a tow back to Houston and a $900 bill to replace a $79 part.

Loc

[Orren Zook]

Not that I am aware of. On the "world" transmission there is a lot that can be done, but not on the five speed.

The five speeds are able to flash a simple error code to the driver if there is a problem and can be plugged into diagnostic equipment at Allison repair shops, as they are electronic too, but as Jon says no mode or operator selectable options.

[Jon Wehrenberg]

Actually the DDEC reader is used to access ATEC codes for the five and six speed transmissions. In fact flashing codes is an excellent way to get an idea of the code subject, but the reader is specific. I had a problem that was actually a connector issue, but the DDEC reader showed the transmission thought it was at minus 20 degrees, at which temperature it is programmed to prevent shifts. We were actually at about 60 degrees so we knew it was either a sensor problem or a communications issue and not a transmission problem per se.

Some software is required.

The world transmission however has the ability to be accessed and connected (I believe at Allison) via the internet and complete diagnosis of its internal condition can be made. The amount of wear on each individual clutch can even be measured, so anybody contemplating the purchase of a coach with the world transmission can avail themselves of some powerful diagnostics at the local Allison dealer.