Allison reprogram

[ready2retire&drive]

I was speaking to my Allison service department and told them I pull a trailer behind my unit about 80% of the time. He suggested I contact Allison engineering and see if they would recommend a program which would pull better and not lug engine as much, After they talked to the Cummins engineers, this was the response, they were pretty good and quick with some suggestion's which may help me.
Gord:
These were the three options that were suggested to me:
·******* Variable – same WOT shift points you have now, but lower part-throttle shift points
·******* SB – same WOT shift points you have now, but part-throttle shift points that are lower than Variable
·******* SA – same WOT shift points you have now, but part-throttle shift points that are lower than SB – this is potentially the highest economy option

Variable is going to lug the engine the least. I went ahead and made a calibration ,with that schedule in case you want to try it.
Matt Lazier
Calibration Support Service Engineer

I am anxious to try this, will take it in after I get it back from RV dealer (having some warranty work performed). Anything to help the unit work easier and keep it healthier. Will update after next trip, hope this helps, gord

[RVermont]

Does this mean the unit will down shift at higher rpm? Or is this related to upshifting while accelerating. My main issue is that the 2018 doesn't have the overdrive switch so if I start going up a hill at 55-60 the unit will slow down to about 40 before it downshifts and then really can not make up any speed. If I am driving 65-70 then it seems to go up almost hills without loosing too much speed. The power band seem right for the 65
Mph speed but is too low rpm for the 50-55 speed. I would love to hear more once you get the change made.


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[ready2retire&drive]

I believe it will down shift quicker at lower speeds keeping the unit in a better torque range. I will try and get the tech to clarify this when I go in. This whole thing started with me asking if they could help with a problem I had which was, when trying to drive up a 2x10( to level one end of unit) on my driveway it would seem to rev up and up and then go, almost like trying to start in a higher gear in a standard. The tech said this was a common complaint and they could reset it. He then asked what I did most with the unit and from there it progressed to a complete reprogram. His explanation was all these units have a base program in them, which are really easy to reprogram and tailor to the conditions the engine and transmission work in. Matt from Allison was super easy to talk too and eager to help out. I hope to get it reprogramed next week and then make a run with it at the end of the month, I will let you know if it helped or can feel a big difference in the drivability and ease of pulling effort.

[ready2retire&drive]

I would talk to Matt all he needs is your unit's full serial number and the serial number of the transmission. Also what kind of weights you may be towing. Let him know what you would like to accomplish. He is a great guy to work with on this. Here is his contact info (matt.lazier@allisontransmission.com). He may then send you to the closest Allison service dept. with his recommendations. The nice thing about this is if it is not quite what you need they can tweak the program, hope this helps.

[Mark S]

Thanks for the contact info. Where did you find the transmission serial number?

[RVermont]

You should have chassis sticker on your drivers side sun visor and it will be listed on that.


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[Robbbyr]

I really wonder why Freightliner / Jayco / Allison (don't know which) deleted the O/D cancel switch the earlier Freightliner Senecas have. Left to its own means, my transmission behaves just as you seem to experience, but a flick of the switch as I start to pull those hills (that I know will require a downshift) I am in 4th gear just that quick. And then it pulls like it was meant to without losing too much of my precious momentum. About 62-63 mph is where my unit tops out on the engine speed governor in 4th gear, but switching it off early allows me to maintain 60 or so on most upgrades when the big semis are slowing to 45 with their flashers on!

I also believe that switch somewhat alters the shift points; at less than expressway speeds I keep it locked out and acceleration seems (slightly) improved and the exhaust brake seems more effective since it stays in a lower gear. Two things helpful maneuvering around in city traffic when necessary!

I wonder if Matt the Allison expert has any opinions on the O/D cancel switch and its use? Could it be easily added back in a newer Seneca? I wonder if the wiring is till there, just unused and not programmed?

[submariner]

Hey guys,maybee some one could help me out.I have been kicking around getting a new Seneca and an trying to learn as much as I can about these units.My question is being it has a 6 speed allison transmission,cant you downshift manually to a lower gear lets say 5th or 4th when approaching a steep grade wnen doing maybee 50 to 55 mph?
Thankyou for any help
Marty

[Mark S]

No, you can not manually downshift to 5 or 4. You can move the shift lever to 3, 2 or 1. That's the only options with the transmission.

[RVermont]

From what I gather and I might be wrong. The allison manual states that the 2500mh is a 5 speed transmission, I haven't counted actual shifts and there is nothing that I can find to state the actual number of gears. There are four position ranges, drive which has a range of 1-5, 3rd which is 1-3,2nd which is 1-2 and 1st which is 1. So if you use 3rd range you are losing both top gears and the unit would be overspeed at highway speed.

To sum the performance up i believe it is good for the majority of roads and hills. It is just when certain conditions occur like people merging into the highway at the bottom of a long hill and you have to slow down, this loss of momentum is more of an irritant than a real problem. Would it be worth a few hundred dollars to install a overdrive switch if available? Yes. Would it be worth a few grand? Not in my opinion however it really depends on how fast you need to go.


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[Mark S]

Originally Posted by Robbbyr

I really wonder why Freightliner / Jayco / Allison (don't know which) deleted the O/D cancel switch the earlier Freightliner Senecas have. Left to its own means, my transmission behaves just as you seem to experience, but a flick of the switch as I start to pull those hills (that I know will require a downshift) I am in 4th gear just that quick. And then it pulls like it was meant to without losing too much of my precious momentum. About 62-63 mph is where my unit tops out on the engine speed governor in 4th gear, but switching it off early allows me to maintain 60 or so on most upgrades when the big semis are slowing to 45 with their flashers on!

I also believe that switch somewhat alters the shift points; at less than expressway speeds I keep it locked out and acceleration seems (slightly) improved and the exhaust brake seems more effective since it stays in a lower gear. Two things helpful maneuvering around in city traffic when necessary!

I wonder if Matt the Allison expert has any opinions on the O/D cancel switch and its use? Could it be easily added back in a newer Seneca? I wonder if the wiring is till there, just unused and not programmed?

Adding the OD lockout would end this thread

[RVermont]

Totally agree with Mark.


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[Mark S]

I just emailed Matt at Allison transmission and asked if we could add a Tow Haul mode, OD lockout or reprogram to downshift at a higher RPM. I received an automated out of office until Wednesday message. Hopefully he will give some good answers.

[Mark S]

Originally Posted by RVermont

You should have chassis sticker on your drivers side sun visor and it will be listed on that.


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Yup, it was right there. Thanks

[Robbbyr]

Originally Posted by RVermont

From what I gather and I might be wrong. The allison manual states that the 2500mh is a 5 speed transmission, I haven't counted actual shifts and there is nothing that I can find to state the actual number of gears. There are four position ranges, drive which has a range of 1-5, 3rd which is 1-3,2nd which is 1-2 and 1st which is 1. So if you use 3rd range you are losing both top gears and the unit would be overspeed at highway speed.

My 2500MH has 6 forward gears. Top 2 are overdrives. Depending on application, overdrive ratios can be locked out by the manufacturer via programming when originally installed in a vehicle.
Here is a data sheet that shows the ratios that the 2500 transmission has built in and other specs in case "inquiring minds want to know"!
http://www.allisontransmission.com/d...k.pdf?sfvrsn=2

[RVermont]

Makes sense that they produce a standard unit and then just use programming to control functionality. I believe your unit has the overdrive switch which has been removed. It will be interesting to hear back from Mark and Gord on the response from Allison.


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[Robbbyr]

Originally Posted by RVermont

I believe your unit has the overdrive switch which has been removed.

I moved my OD cancel switch to make it very easy to operate, since originally it was installed at the far right side of my switch panel. All six gears are available in my unit unless switch is activated and then it is only 1 - 4.

[RVermont]

Sorry. I meant it has been removed in the new Senecas. 2017-2018 models don't have the switch.

All the switches in the drivers compartment should be moved, kind of surprising that a vehicle chassis that is designed for constant commercial use has such poor ergonomically located buttons and switches.


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[McGintys924]

I am with you on the poor ergonomics of the cab as nothing is at your fingertips, and some things are hardly at my arms reach (cruise control activator switch). I would still rather be driving it than our car however as it is a pleasure to drive.

In another life I used to work on boats. Mercruiser made one engine in particular (496ci) that had a $10k price difference if it made 375 hp vs 425 hp (HO version). When a customer had ordered (and paid for) the larger HP and it came in from the factory with the lesser HP engine, a merc tech came from the factory with a little laptop that was almost handcuffed to his wrist. 30 min later with it connected to the boat it was now the 425 HP 496 HO. There are probably many times that the things we purchase are generic but can be reprogrammed if nessesary. I am willing to bet that Allison tells us the OD cancel switch is an easy put back for those of us who don't have one. Wires are likely there, and computer could be programmed for its use. I will be excited to see what Wednesday holds.

I too feel that it waits a little too long to downshift, but I figured this had been done on purpose to prevent high engine RPM in a Diesel engine for prolonged periods of time as would be experienced on climbing a steep grade.

[Mark S]

This is the email I just received from Matt at Allison transmission:

Mark,

3ALACXFC0JDJG1060 currently has the performance shift schedule on secondary, which is controlled by wire 142. If the OEM has not provided any means of controlling this wire, then you will always be in economy mode.

I made a calibration that has the shift schedules switched, so that it will default to performance. Your service outlet will need the TCM assembly number to install it. The TCM assembly number is:

6ABR0D0D

Thank you,
Matt Lazier
Calibration Support Service Engineer
O 317-242-2287 | M 248-640-9421
matt.lazier@allisontransmission.com
Mail Code M5C
One Allison Way
Indianapolis, IN 46222-3271

I guess I need to make some phone calls now.