Transmission Shift problem

[rbeecher]

Hi Tuga,

Does the tranny need to be at normal operating temp for the code test? Trying to remember...

Richard Beecher
02 Marathon XLII 45
96 VOGUE XL 40 For Sale

[merle&louise]

Richard,

Yes I think it does have to be at operating temperature (180 degrees)and level for the correct oil level reading. However, I would assume that the codes would be displayed regardless of whether or not the engine is at operating temp.

[aggies09]

Getting the codes was a very easy task. It does not have to be at operating temperature. I displayed two codes that indicates an "open circuit" and an excessive temperature. I am trying to get into an Allison service center later this week to have it checked out. I will keep the group posted in case anyone else experiences same.

[merle&louise]

Tony,

Is your transmission temperature gauge showing higher than 210 degrees?

That is the limit where the thermostat is supposed to open. I thought mine was overheating, but Allison told me that as long as it stays under 210 it is o.k.

Hope it is something simple to fix like a bad sensor.

[JIM CHALOUPKA]

Tony, how many miles are showing on your odometer.

I hope your alarm is a sensor problem, as the other thing that can cause excessive heat is slippage, and that means clutches or pump pressure.

Good Luck, JIM

[Jon Wehrenberg]

210 degrees is not the transmission limit. The temperature is sensed at the retarder output, the hottest possible temperatures will occur here.

If I am not mistaken the transmission computer will reduce the effectiveness of the retarder to keep temperatures below 300 degrees. As drivers we should work to keep the temps down anyway because high temps are not good for the fluid. My guess is a sensor is reading temps incorrectly.

[phorner]

Transmission temps of 200 degrees or so don't seem that out of the ordinary to me. Ours runs typically at 205 to 215 depending on ambient air temperature, grades and use of the retarder.

An occasional, almost momentary, reading of 220 or 225 was also not that unusual, with 225 being about the maximum that we experienced.

[aggies09]

Tuga: I have never seen my gauge heat up above 205. It typically reads right at 200.

Jim: I forgot the exact mileage, but it is about 82,500.

My initial conversation with Allison indicated several things to check upstream and if nothing was evident there the reservoir would have to be opened up and there are a couple of sensors there that need to be inspected. It looks like it is going to be next week before I can get into the shop. Holidays and vacations.