Every time I have fuel saver light I have MDS on.I can hear it swap back and forth plan as night and day with my exhaust.I have paid attention to how mine functions,Its EVERY time fuel saver comes on MDS comes on.Even at very low speeds and before any measurable temp on the temp gauge. I had a FLASH update done many months ago.After the REFLASH the MDS/Fuel saver light are a lot more sensitive.

 

Ya a loud horn or the mygig radio voice says MDS is now on.

 

I hear what you are saying, but Chrysler states that MDS will not engage until the engine is at operating temperature.

Mine comes on with a cold engine also and I doubt it is in MDS mode at that time, more like an economy mode, light on the pedal.

The only real way to tell would be to monitor one of the spark plugs that turn off in MDS mode.

I saw this done on one of these forums, a person that did just that. Don't remember which one though. He ran a wire to the spark system and to an LED in his cab. When i was on it was 8 cylinders, LED off it was on 4 cylinders.

 

With my exhaust I can hear EVERY time it drops four cylinders.After the latest FLASH UPDATE mine comes on COLD engine right out of the yard.They made some changes that were incorporated in the NEW flash.MDS lots more sensitive after the flash update.

 

Service techs have a scanner they plug in that shows them full details of MDS activation while driving. I watched a tech do that in our Grand Cherokee while diagnosing some issue. They can see all of the parameters that MDS bases its 'activate/deactivate' status on and then see when MDS activates.

Rob

 

I'm sure service techs do have a scanner/interface. Sad to say I don't have one or most of the rest of us here don't have one either.

Since you have seen them diagnosing the MDS system maybe you could help the rest of us on some of these requirements for it's activation. Seems to be a lot of confusion on this.

As it stands now and within this thread, most people think the Fuel Saver light is both for the MDS system and economy mode, ie: the light doesn't always mean it is in MDS mode, given the parameters from Chrysler and observations by some individuals.

I was saying the easiest way for "us" to determine if it is on or not is to build this little LED monitor to actually see when the ignition system is on or off.

Any additional information would be helpful and appreciated.

 

What I find amazing is all the bitching about not having the light cuz of buying and early model and well we finally get a fix and you have some yahoos in here tearing it apart. All I can say is the reason we get some of these things is because Chrysler or in this case Dodge monitors these forums to see what we are saying about the trucks, whatever and I think they go from there to try to help us get our trucks to be the way we want them.
We wanted the light we got it now why all the negativity. It works when it is supposed to. Mine does not come on right away unless it is a very warm day and the truck has been in the sun or it will be a few minutes since it's summer and warm here. When it was cold it took a few more minute before it appeared, depending on how I drive.
I think this thread has run it's course...reallly it is just like kids on the playground now.

 

72 is correct. Time to close this thread. It served its purpose. I now have the light, thanks to Dodge. It works. I had the mds update flash for drivability. It works. There is nothing negative about having the fuel light added. For those that are annoyed. Just unselect it in the evic.

 

Well, on the Grand Cherokee (2005 model) the MDS system came on based on parameters being within range for things like engine temp (maybe coolant temp?), RPM, vehicle speed, engine load, and a couple I don't remember.

My knowledge of the ECO light on the RAM is limited to speculation based on how the Jeep worked and what I see when driving the RAM. I see that the ECO light never seems to be on with accelerating, even lightly. I also see that the ECO light comes on at slow speeds. MDS on the Jeep didn't activate until something like 30 mph. MDS on the Jeep could also be active when under light acceleration. The RAM's ECO light doesn't act like this.

All I'm saying is that the ECO light is not 100% exactly an MDS indicator light unless MDS has been dramatically redesigned. They are related but slightly independent of each other. Or maybe it was dramatically redesigned. I don't know...

Rob

 

Just wanted to say thanks to those who put out the info on this flash. Got mine done yesterday and was amazed on how many times it comes on. Again Thanks to all for the info.