[77newell]

  Hey all (well actually only those that have or had recently enough to remember), I have a question about how your electronically controlled Allison transmission hooked to a 2 stroke Detroit Diesel shifts. My 93 coach upshifts only when the engine has reached maximum governed speed which is 2100rpm and will stay in that gear unless road speed really drops no matter what I do with the throttle. With the 77 old school mechanically controlled Allison if as speed started to drop going up a hill I mashed the throttle the transmission would downshift a gear. The newer coach doesn't do that. How does your coach work?

The newer ATEC (I think that stands for Allison Transmission Electronic Control or something close) have an input for throttle position (TPS - throttle position sensor that feeds both the engine ECU and the ATEC. My 93 coach has that input disconnected. When I asked the Newell factory about that I was told that that was intentional to improve fuel mileage. I can see how avoiding constant downshifting could decrease fuel mileage but it is also distracting to have to manually downshift when going up hills to prevent lugging the engine.

I believe it will be easy to connect the TPS, but I don't know if the ATEC module will then also need reprogramming. I'm trying to find information just in case I decide to at least try it.

Again, how do your coaches work?

[rellick]

I posted this link for sopicki also this guy is the allison guru and very helpfull. TKT Sales: Allison Transmission Parts Supplier

[NewellCrazy]

Thanks for the link Keith I have bookmarked it for future reference in case others need help.

[77newell]

I talked with a local Allison shop and was told that if I hook up the TPS to the transmission ECU I will have to have it reprogrammed.

I'm wondering if those of you with 90's coaches with the 2-stroke have the same shifting pattern as I have which is it up-shifts only when the engine RPM maxes out and then downshifts only when the engine is lugging unless I manually do it.

[ccjohnson]

Sounds like our shift pattern. I usually manually downshift before the transmission does on long uphill grades.

[rellick]

Jon, That would bother me also, did you tell Allison how your transmission is acting? they should be able to change shifting points on it, or have different options for ecu programming. A tps would help, not sure why Newell would omit that part? my 6 speed will shift down if you mash the throttle. I would recommend calling Ted at TKT sales he is very helpful and really does know his stuff, ecu reprogramming is not really all that expensive should be around 300-500. He would have a tps for you as well.

[MrE]

Perhaps we can schedule a "Day at the Drags" during "Rellick's Rally" next year where Ted at TKT Sales will show up with his ECU programmer? I always wanted to know which Newell is the fastest.



If you're not into drag racing your coach, here's a video of another option.
[video=youtube_share;ohkAxbeMxVo]http://youtu.be/ohkAxbeMxVo[/video]

[77newell]

Keith: yes I would prefer to be able to mash the pedal and get a downshift. I have an electronic engine and therefore have a TPS (throttle position sensor) signal, it's just that Newell decided not to connect that signal to the Allison ECU (electronic control unit) so there is no way for the transmission to react based upon throttle position. The Allison shop stated the ECU would need reprogramming following connecting the signal otherwise it would just continue to ignore it. While reprogramming they could set the various shift points accordingly. I've found a diagram online showing the wiring, all I have to do is find them in the coach. My message here was to find out how common my current setup is and reactions by those that have it.

[rellick]

Jon you are definately the life of the party around here!!lol that's gut busting funny!!

[MrE]

The video certainly shows how poorly constructed those cookie cutter motor homes are.

[Neweller]

Jon, are those the true meaning of flap jacks! Once they pulled the cheap gnarly cabinetry out there wasn't much integrity was there. Makes a Newell or bus conversion much more sought after.

[rellick]

Jon, If your wiring is similar to mine, ( I think alot of the allison wiring harnesses are the same or close to) my plug for my tps comes out on the drivers side near the rear of the transmission, yours may be tied up somewhere in there. If I remember correctly its a 3 pin plug inline or flat, the allison manual will have the color and the wire number, I think there is even a picture of it. Then you would just have to mount the tps and run the cable to your injector pump, hopefully they have a place where it should mount. Hope this helps

[77newell]

Hey there Keith: the Allison ATEC (the ECM module in my coach, versus the newer WTEC) diagrams I've found that show the interaction with the 8V92TA DDEC III (Detroit Diesel Electronic Control version III) shows something different than you have described. It shows the signal wire (#105A) coming from the throttle pedal and going to terminal 6 on the ATEC. It also shows a connection to wire #105A somewhere between the pedal and the ATEC of wire #105B that goes to terminal P on the round plug on the DDEC. What I'm planning on doing is see if ATEC terminal 6 has a wire attached and then follow that wire. It is possible that the wire is already there but the ATEC lacks the programming to use the signal which would be really cool. The alternative is that I spend lots of time tracing wires.

I wonder if what you are referring to as the tps on the transmission is some kind of speed sensor rather than a sensor measuring throttle position. The diagram I have shows the only reference to the throttle sensor as being in the cockpit. I'm a thorough novice on this system so I could be out in la-la land somewhere so I appreciate your input especially given all the work you've done on your 77. I'll let everyone know what I find.

[rellick]

Jon, mine is a wtec11 and has nothing to do with the throttle pedal, it is a separate unit attached to the the throttle at the pump similar to how the cruise controls are connected, they show a picture of it in the world transmission manual. It may be different than your setup. It sends a signal to the allison ecu then it communicates with the engine ecu if it has one, my engine is mechanical but the trans ecu has the plug for the electronic engine, which is also different than yours. Hopefully it is an easy upgrade for yours.

[77newell]

Keith: thanks for clarifying. Your configuration is one I would never have guessed but as you describe it it all makes sense. Different engines, different wiring.