Exhaust Brake C 333ISC Target RPM Setting

[Flagelpater]

My 2005 Monaco Knight, Cummins 330 ISC, Allison 3000MH is downshifting at Max RPM of 2250. If it was shifting at 2600 RPM, could the value change without resetting the software? I can not be sure this coach ever did reach 2600 RPM. I also can not find the operational specs for the setting either.

[ua40j]

Here is the Cummins EPA data for your engine. Just click on your engine.

Cummins Every Time - Motorhome - EPA 04 ISC?

Based on this data, your engine is shifting at the correct rpm.

Just in case though, that you have 2002 engine (Cummins had some difficulty in meeting EPA 04 standards and had credits to put 2002 engines in after 2004, the engine max rpm is the same as EPA 04.

[Flagelpater]

Thank you for the link. I could only find the RPM Limit for Under Power. I think there is another RPM Limit for when you are using the Exhaust brake. One limit for under power, and another when you are Grade Braking. My 03 and 04 would go up to 2600 RPM down grade with the Exhaust Brake ON. I am not sure this 05 Knight ever went over 2300 RPM. Has anyone had a unit that Monaco failed to program for Exhaust Brake operation? That may be my problem and the reason it is shifting at the lower RPM Limit

[ua40j]

As I understand the exhaust brake operation as tied to the transmission, the brake will only go to max governed rpm and will downshift to keep it there as long as possible.

But I don't think it will always go to Max exhaust brake rpm (300 to 400 rpm over governed) unless it's forced to.

I think you're seeing correct operation unless you're experiencing these differences over the same grades as your 03 and 04s.

My 02 ISC only shifts to maintain max governed. I've seen go over max governed a couple of times but I was headed downhill way too fast and had to supplement with service brakes.

[Flagelpater]

The way it was working on my 04, as you started down hill, from level cruise, in 6th Gear, the EB comes on and the RPM builds to 2600 RPM, then it downshifts one gear, the RPM will be about 2100. As the RPM builds to 2600 again the transmission shifts down another gear, this goes on until you reach 2nd gear, if that was the programed Grade Braking Gear. By not going to the higher RPM most of the breaking is accomplished with the Service Brakes. The higher RPM is needed to derive the maximum engine braking. As I understand it, the Governed RPM is for the Engine system and the Transmission is supposed to govern the Grade Braking RPM.