2012 Speed Limiter Not Working

[BigCE]

I had a customer request a 105kph speed limit be installed, I changed both limiters to 105kph and it doesn't seem to be working. Anyone ran into this before?

[Road]

Your most likely using someone's modified file that has changes your not aware of....

[GMPX]

Mike, is the Ram like some GM vehicles where the vehicle speed limiter is not actually controlled by the ECM?

[Road]

Mike, is the Ram like some GM vehicles where the vehicle speed limiter is not actually controlled by the ECM?

My knowledge is it is controlled solely with the ecm, but like GM you can change how it is controlled within the ecm. So if you are using a file that has it turned off then you will not be able to use the speed limiter tables or changing them will have no control.

[CumminsTwang]

Halfway through the 2016 model year, Cummins made a logic change inside the ECM. Many things, inside of Ram tuning changed to flash only. Other things, like speed limit changed from a calibratable to a trim. Trims can be changed realtime. Calibratables need to be flashed. One thing about trims...when you key off they reset to the stock values. Therefore, the speedlimit needs to be changed EVERY time the vehicle is keyed off... Hope this helps!!

Respectfully,

PCS Tuning

[Road]

Halfway through the 2016 model year, Cummins made a logic change inside the ECM. Many things, inside of Ram tuning changed to flash only. Other things, like speed limit changed from a calibratable to a trim. Trims can be changed realtime. Calibratables need to be flashed. One thing about trims...when you key off they reset to the stock values. Therefore, the speedlimit needs to be changed EVERY time the vehicle is keyed off... Hope this helps!!

Respectfully,

PCS Tuning
If you make changes while the calibration is loaded into ram then it will revert back when the power is cycled. When you flash a calibration what in that calibration gets loaded into ram...

[GMPX]

Trims can be changed realtime. Calibratables need to be flashed.
As far as I know the trims (or any realtime changes) can only be done over J1939, for 99% of our customer base they are using the OBD-II port so such features aren't available.

[CumminsTwang]

The speed limit parameters reset every time a power cycle event occurs. Anything that is a trim will reset during the power cycle events. That is why it will not take effect. If you notice the newer truck will not accept timing, fueling, etc changes until it is flashed... I assume they pulled this functionality out with a calibration/software upgrade.