RV Transmission – Part 1
About 2/3 of the way between my house and destination Missoula a little warning light came on… icon looks like a round gear and it had an exclamation point in it – YIKES, WHAT NOW??? As soon as there was a safe amount of shoulder I stopped and got out the manual which has only this to say about that particular icon: “Transmission Fail Warning Light”. No other info like “it’s ok to drive for a bit, but get service soon” or “DON’T DRIVE ANOTHER FOOT”… I phoned my shop in Kalispell and it was generally agreed that things were not likely (no guarantee) to go bad soon and there were no symptoms in operation, i.e. shifting so I went on with no problems.
A Workhorse (my chassis type) shop could get me in yesterday provided I arrived at 7 a.m. which I did and spent 5 1/2 hours during which the tech tried to get error codes off the chassis computer, reset the computer, unplug -check – re-plug the programming modules for the transmission – a couple of test drives and finally a drive up the road to the Allison shop at which time I put together that the first place really did not have the equipment or knowledge to work on the Allison transmission. However, it MIGHT have been the modules which would have been quick and easy fix AND I never would have been able to get into the Allison shop this quickly without the “referral”.
The Allison tech put HIS computer in contact with my chassis computer and “Voila!” the fault code and while it is not absolutely definitive, the code plus the symptoms pointed to an electronic torque thing (Al, do NOT panic, I’ll get all the correct terminology!). So, I have an appointment for tomorrow morning at 8 a.m. at the Allison shop.
So the symptoms.. There was no indication of trouble in operation, shifting felt normal, no unusual sound, the gear icon was originally the only trouble indication. During one of the test drives, while we were turning around, the turn was a bit tight and the tech went to back up. Transmission would not go into Reverse and another light came on “Range Inhibited”. We turned off the engine, restarted, now we could go into Reverse. We tested this a couple of times – so, on a fresh engine start and/or before the gear icon appeared (it was appearing at about 28 mph or right after the shift from 1st to 2nd) Reverse was fine. But after the gear icon appeared, no Reverse, but we could put the transmission in 1, 2, 3 or Drive.
All of this made sense to the Allison tech in light of the fault code he was reading…Here is part of the explanation… First you need to know that 1st gear might use and A and a B “gear thingie”. Reverse might use “B and R”, i.e. there is some overlap and if “oops there is trouble with “B”, but the computer KNOWS that it already was able to use A&B, then it goes “back” to the last thing that worked and “inhibits” the full gear range. So…
- The transmission computer is sending a trouble code (that’s the fault that points to the torque thing) which lights up the warning icon.
- When Reverse is called, the computer believes it cannot go there and so the Range Inhibited message appears indicating that some transmission sequence is unavailable.
I kind of sort of get this and will get a bit more clarification tomorrow and correct anything I wrote wrong… Yesterday, the Allison guy was doing the Workhorse shop a favor by spending 15 minutes to use their computer to see the fault code.
It also turns out that Allison “plays their cards close to the vest” – they pretty much insist that their transmissions do not fail, it is the wiring, computer, electrical or engine and I guess this is mostly true. Only one bit of the electrical stuff for the transmission is actually theirs. In the name of protecting the Allison shops, they don’t let much info out and tech support only for the Allison shops – which is understandable but I didn’t KNOW that or could have skipped the Workhorse shop and 4 hours of labor (actually 5.5 but the service guy decided that was unfair to charge and I thought 4 was fair also – I knew the $$ racking up – I saw the labor rate sign – I didn’t expect them to give their time away BUT the Workhorse tech was a bit chatty and I wimped out on being assertive about it aside from retreating behind my computer…).
Based on the fact that “Allison transmissions never fail” and all of the info the Allison tech and I discussed, it was decided that the risk of driving the 2 miles back to the RV park and then returning to the shop on Friday was minimal as far as total inoperability (read “call the tow truck”) so I am back at Jim n Mary’s until tomorrow morning. If the problem is what they think and they can fix in 1-2 hours we will return yet again to Jim n Mary’s and go back home on Sat afternoon or Sun morning. If it’s something more awful, we’ll (Bob, Karl, me) stuff ourselves, the remaining frig food (I’m eating as much as I can!), computers and a few clothes into the Jeep and go home tomorrow.
Bob takes things in stride…
