I know this is the Eco Hubs thread, but since we had some lengthy discussion here about my feelings that an exhaust brake was critical for mountain driving when you have Eco Hubs installed I thought I would post a follow up. So, back to the exhaust brake conversation. Since I have now installed my new PacBrake, Switch, solenoid, and associated air lines, I've now gotten focused on changing the way the exhaust brake functions to make it something that is useful in a truck that is now capable of cruising 75mph on the highway.
There was a previous post that identified that there is a "target gear" setting in the TCM. I have the Allison software, but can't use it as it needs to be activated. Way too expensive to buy, $1100 and then $590 each year to keep it active. So I'll have to find a commercial Allison tech here locally to change the target gear. Where this gets exciting though is that there is even more useful changes that can be made in the ECM with CAT ET, which I also have. These improvements require that you also have the ECM setup for cruise control. Here's what I (I means my daughter who is a computer genius
have done and it makes the exhaust brake function exactly how I want it to and essentially the same as the exhaust brake in my 2014 Ram.
In CAT ET you go into the cruise control menu and set the cruise control to "Latched". There is also a setting called something like "auto retard threshold" The lowest value this can be set to is 3 mph. We had to shut the truck down and restart for all of the changes to take a affect. Now with these changes you have three different exhaust brake modes based on the status of the cruise control.
Exhaust switch on/cruise control switch off - in this mode the exhaust brake engages when you lift your foot off of the accelerator pedal. The downshift to the target gear happens in this mode.
Exhaust switch on/cruise control switch on but cruise not set - in this mode the exhaust brake engages when you press the service brake and stays latch on whether you are on the brakes or not until you depress the accelerator pedal. The downshift to the target gear happens in this mode.
Exhaust brake switch on/cruise control on and set - in this mode with the cruise set when you are coasting with your foot off of the accelerator pedal, the ECM automatically modulates the exhaust brake to maintain your set speed. When your speed reaches the threshold value you set over the set cruise speed the exhaust brakes engages and stays latched until your speed is back withing the threshold range you set. In my case the threshold is set at the minimum 3 mph value. In this mode, the trans does not downshift to the target gear.
Hope you find this info useful. For me this is a MASSIVE improvement in the exhaust brake function and will be even better once I have the target gear changed.