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Transmission problem
Towards the end of a 1500 mile trip, the Allison B 500 transmission in my 2002 Marathon XLV started doing something funny: I would start off and when it was trying to shift from 2nd to 3rd (or maybe 3rd to 4th, not sure), it would pop into neutral and the keypad would just flass “D”; if I hit the N button and then hit the D button, it would engage and then continue to shift normally.
At first this was intermittent but by the last day of travel it was occuring every time it went up through the gears. Got it to it’s winter home but now it’s time to move. Obviously needs to get into a shop but I was wondering if I should be prepared for just something bad, or something just horrible. It’s 30 miles of freeway to the shop – safe to drive it functioning this way? It cruises fine, downshifts OK, no other problem than the predictable glitch upshifting.
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11 Replies
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Mike,
It is definitely something Allison needs to sort out, but the flashing D occurs if I try to put it in gear when the revs are too high such as on fast idle, or if I haven;t got my foot on the brake.
If you have slides the issue could be related to a problem indicating to the transmission the slide is not closed.
Whatever it is have you tried reading the codes? You can access them through the key pad. If you don’t have the manual let me know and I will try to pull out my information so you can see if it is something you can chase yourself.
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Flash the codes to be sure but it sounds like the turbine speed sensor is acting upgood luck
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Mike,
I will send you a private e-mail with my cell number. I have experienced exactly what you have described last year.
It’s not a serious problem and you can dismiss the B-500 being removed from the bus. But, coach must go to Allison for repair.
I’am not trying to hide what this fix is all about to other PC members but will be easier for Mike with contact phone numbers I have..
I want to give Mike info I have on this issue which also scared the hell out of me. The Allison tech along with his team leader including myself spent a lot of time on our bus.
When all the pieces fell together the fix was less then 30 minutes…. 6 hours later.
Mike, open your e-mail through your profile update or send me a e-mail through mine.
AL
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Email is open on my profile. Thanks all,
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Al – thanks for the tip – turned out to be an easily solved problem. Thanks to this forum I think I saved a ton of $$$$.
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How about letting folks know what the problem was and how it was fixed?
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The inquiring minds of coach owners want to know!
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Short story of repair was a ground issue at ECM. It required pin replacement and wiring update. Three (3) ECM’s were installed as they learned from there Allison factory techs that …HAD.. to be the problem. It was not.
I was in contact with Mike (dfwcantor) and after our phone conversation faxed him the Allison shop ticket so when he arrived at Allison that invoice was a detail customer complaint …cause and cure and not some BS where the owner does’nt know what he’s talking about.
I had a very large shop Allison $ ticket. On the plus side the problem was repaired properly.
AL
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key point was electrical problem where codes were not that helpful. I had visions of my tranny sitting on a bench somewhere being “rebuilt” …. I had a large bill but also had a lot of maintenance done, work on the shifting priblem accounted for less than a quarter of it.
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Now heading back from 6000 miles+ traveling this summer, and the tranny started doing exactly the same thing! Looking at service ticket from when they fixed it last time, it says they replaced grounds on TCU. Anyone know where the TCU is on a 2002 XLII? maybe I can do it myself. I’ve looked in engine compartment, drivers bay door etc, can’t locate it.
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It should be in the front service compartment (where the steering gear and windshield washer bottle are located). It is mounted on the ceiling of that compartment in that year.
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