During our recent trip to the Northwest we experienced two mechanical problems. First the ABS and ATC lights came on on our way into Yellowstone. At first we did not see any adverse effect. Before we made it through we were having problems with the transmission shifting up from 3rd to 6th. It was like it was jumping in and out of gear.The closest Allison Rep we could find was in Rapid City SD that would work on the coach.
The first issue was to address the ABS problem. The mechanic could not get the ECM to talk to the computer so it was condemned. The whole time saying that this could be causing the shifting problem or surging. Almost 2 weeks later the ABS?ATC was corrected ( broken wire on rear wheel ), still have transmission problems. The were no codes in ECM on the transmission or engine. The fluid was checked with the dip stick instead of electronically. With the unit hot it was about 2 qt's over full. This was drained off, gauges hooked up to measure pump pressure. We drove the coach and no shifting problems. To make a long story short after several trial and error checks and a lot of man hours this solved the problem. I don't understand why this would have been the problem. We drove the coach about 8K since the transmission was serviced however it wasn't in the Rocky's.
Perhaps someone can explain the problem or do I still have a gremlin in the background. I would like to thank Dave and Jim Edwards for the support and information.
Point of interest the ECM's for the transmission and engine are located under the shiftier panel. The electronic oil check will tell you if you are low not over full.
