Cat C-12 and Allison 4060 Reprograming

[Dick Simonis]

I'm getting ready to take the Beaver to a Cat dealer (thinking Empire Cat) in Tucson for some maintenance....mainly an oil change and etc.  While it's there I'm also thinking about having some reprogramming done.  Mainly:

1)  Currently the Jake Brake defaults to 2nd gear when activated by the switch on the console.  It also disconnects the cruise control.

2)  I would like to have it default to (I think) 3rd gear...perhaps 4th.  Still thinking about that.  My logic is that a 2nd gear is just too much braking in most circumstances and I can always manually select 2nd if need be.  The other thought is that I don't want to go fumbling for the tranny pad at higher speeds if it defaulted to 4th or 5th.

3)  I would like to have the Jake engage with an application of the service brake pedal instead of when releasing the go pedal.  I'm not to comfortable with the rapid shifting when the accelerator is used.  Not explaining it well but I reckon you know what I mean.

4)  I would like the cruise control to stay enable until the Jake actually engages and not upon activation of the switch.

I know there has been multiple conversation regarding the engine going to 2300 rpm when the Jake downshifts but the manual seems pretty clear that that is normal and OK.  Problem is, there is also some well reasoned opinions to the contrary...so I'm kind of twixt and tween on this subject.

I'm curious as to what others have done along this line and if what I looking for is possible/practical.

Thanks for any input.

Dick

[Gerald Farris]

Dick,
Changing the engagement trigger for the Jake brake is very doable on your coach, however I think that it requires a wiring change in the left front electrical bay to accomplish it on your model coach. It is a fairly easy wiring change, however if the Cat dealer is not familiar with the way the coach is wired, it might get expensive to pay for their learning curve.

The Allison default gear with the Jake brake is in the Allison programming, and I do not think that all Cat dealers can reprogram the Allison. So you may want to call the dealer first to see if it will be necessary to see an Allison dealer for this programming change.

As for the issue of what gear to set as the default gear, I very strongly prefer 5th or 6th. The use of fourth or lower as the default will remove the option of using the Jake as a speed control on long down hill slopes where you can maintain the speed limit with only slight engine braking. I use 5th in my coach as the default, and there is no way that I would go to fourth as the default because it gives to much braking for so many situations that you loose the use of the Jake in situations where only slight speed control is needed.

Gerald    

[Dick Simonis]

Gerald,

Thanks for the info.  I'll probably take your recommendation and program the tranny to 5th.

Regarding the wiring change.....what is this for, the cruise control interlock???  And, do you have any idea of what I should look for to see if this is necessary?

Is the progamming I'm looking at all Allison?  I have several choices one of which is an Allision dealer (H.H. Williams) but they may or may not be able to reprogam a Cat ECU if necessary.  Anbody can change oil and check the coolant SLC is suspect.

[Phil Sales]

Dick, I agree with Gerald on the ability to use the Jake more,and had mine reprogrammed to not shift out of sixth. It still shifts down as your speed drops to 5th and 4th in logical order. I had mine done at the Allison shop in Syracuse last summer. The price was $120.00 took him about 10 min, then he looked underneath to do a leak check, spotted nothing. He checked the oil stick , found out  my trans was not set-up to check the oil on the console and was converted to Transyn only 20,000 ago. was well worth the $ 120.00

[Dick Simonis]

Interestingly I called the local Allison dealer, and yes they can reprogram but insisted the 4th was the best they could do.  Now I have to figure how to diplomatically tell him he is full of monkey dung.

Got a call in to the local Cat dealer to ask about reprogramming the thing to come on with service brake application....with a bit of luck they can do the tranny, but not holding my breath.

Then there is the wiring Gerald spoke of....still have to attack that, but I figure the end result will be worth all the effort.

[Marty and Suzie Schenck]

Unless the CAT dealer you are going to is an Allison certified service facility you will have to take it to Allison to reprogram the downshift defaults. I had mine changed to 6th gear and love it. The CAT dealer is the one that can change the parameters for the Jake Brake and the cruise control. While you are there he can print out exactly what all the parameters are set at for future reference, you just have to ask them to do it. Marty