I hear people talk about knowing when their MDS is on or off. Is there supposed to be some indicator light showing MDS status that you can enable via the EVIC somehow, or are people thinking the ECO light relates to MDS, or is it just that sometimes you can 'feel' it engage and disengage?

Rob

 

In a 2009 you go to the setup screen and there is a setting to show the fuel saver light or not. I believe that in a 2010 it says ECO or something like that instead of fuel saver

 

OK, thanks. But the 'ECO' light is not directly related to MDS being on. MDS is on engaged often then the ECO light displays. Hence my confusion.

Rob

 

The ECO light and MDS are directly related.
The ECO light (2010) comes on when the MDS is engaged. I believe it says Fuel Saver for the 2009.

 

09 mine says Fuel Saver is to let you know when your MDS in active

 

You sound very confident. How are you so sure? I was under the impression that ECO was an indication of driving 'lightly', in a way that gets great gas mileage. The MDS, on the other hand, can come on far more often. In our Grand Cherokee it could be on while driving 50-65 mph and actually accelerating lightly. The ECO light is NEVER on while accelerating.

So, I've always been under the impression on the RAM that ECO <> MDS. If you can show me something that proves that wrong I would be very interested, because it means MDS works significantly differently on the RAM than on the Hemi in the Jeep.

Rob

 

Your impression is correct.

 

You raise an interesting question.

Everything I read about MDS and the "fuel Saver" light says that it will not come on until the engine is warmed up.

I have an 09 2008 build and had the flash to update to the fuel saver indicator, But my "Fuel Saver" light will come on with a cold engine, right after I pull out of the driveway.

The question is, is it in MDS mode at this time? According to the published information it is not and is most likely an indication of driver efficiency.

So I would have to believe that it is an ECO/MDS indicator (driver/engine) or strictly ECO.

Questions abound.

 

My source is the owners manual for my vehicle, Page 228:
"The FUEL SAVER MODE message will display above the average fuel economy in the EVIC display. This message will appear whenever MDS (if equipped) allows the engine to operate on four cylinders, or if you are driving in a fuel efficient manner. This feature allows you to monitor when you are driving in a fuel efficient manner, and it can be used to modify driving habits in order to increase fuel economy."

The light may or may not come on during acceleration simply due to the level of acceleration. If the 4 cylinders can handle it the light is on. If it requires 8 cylinders the light is off.

 

Therefore:

If MDS is activated you WILL ALWAYS get the ECO/FUEL SAVER msg.

If you get the ECO or FUEL SAVER msg. it WILL BE either MDS activated or driver efficiency in which case I assume that equates to MAP (vacuum) readings.