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No Forward Motion!!!
No Forward Motion.
I had a failure in my Allison transmission ECU! Yikes!!
The symptoms were that the transmission would not shift into
forward or reverse. Instead of the
normal two digits being indicated, only the right hand digit would show and the
shifter would beep 14 times each time the key was turned on??.It happened when I was attempting to pull forward after
fueling at a Pilot fuel stop on IH-69, north of ,
. We blocked the fuel island for several hours
until the Allison technician arrived. He
placed a test ECU unit in and I was able to move to a parking spot in the truck
parking lot. There is no way to bypass
or manually place the transmission in gear, according to the Allison tech. The Allison transmission ECU has to get it status
from the engine computer
before it will allow a transmission gear shift.
After the ECU was replaced and software uploaded, all was OK again.This is one of those things that no amount of preventative maintenance can manage.
Comments.
If the coach does not move when you place the transmission
selector in gear, you have a 45,000 pound chunk of stainless and iron. This will most certainly bring a very
desperate feeling, I can attest. We
spent the night in a Pilot truck parking lot and was on our way by the next day. Two service trips later (one at and the second to bring the new ECU at the next day), 85 miles drive from each way to our location, a new Allison ECU and
of course $3,100.00 cost. Now that I
look at it, it was part of the cost of ownership. After traveling for 10 years, I have had two
occasions where my motor home was disabled.
This was one of them.We were held up for 24 hours until repairs could be
completed, then on our way.The ECU is located in the pneumatic compartment under the
drivers seat. It is an aluminum box with
a couple of cables plugged into it. A
couple of items to remember, if only one digit (the right hand side), the
shifter has identified a fault in the ECU and will not allow any transmission
action. Second, I asked the Allison tech
about low temperature issues that would prevent the transmission from
shifting. He stated that two low
temperatures exist in the Allison ECU.
At minus 20 degrees, the transmission will not shift above second gear,
until the oil heats up. At minus 50
degrees the transmission will not shift into drive or reverse until the
transmission oil heats above the stated temperature. Hell, I’m ,
if we ever see any minus degree temperatures on the thermometer, we stay inside
where it is warm……..FYI
Hector
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3 Replies
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Glad you are back on the road.
There is a second condition that will prevent any transmission from going into gear. That is an RPM above idle. On my coach I also need to have my foot on the brake. The point is that like the suspension our coaches continue to evolve and there are more and more conditions that have to be satisfied before we can engage D or R. Folks with slides also have conditions which must be met before the transmission can be shifted out of neutral.
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Hector, thanks for your story. Wondering did Pilot attempt to make you get a tow out of the fuel dock?
JIM
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The Pilot I was having the problem at did not seemed to be concerned. They sent a maintenance guy out to block the lane with a plastic caution barrel. I guess they have seen their share of broke down trucks.
Hector
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