How to tell if MDS is on or off

jwheeler · Apr 22, 2015

Quint said:
This is an old thread, but in the 2015's is there any visual alert in the EVIC that says that MDS is on? I've noticed the droning noise at times but I'm not always sure.

No. A scan tool is the only way to tell when it is actually in mds mode. But you can usually hear a change in exhaust sound.

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Quint · Apr 22, 2015

Thanks - that's what I thought. It's too bad as it would be nice to know when it's on as I might be less tempted to get on the gas

RCFiddyOne · Apr 22, 2015

IHRedRules said:
I just bought a 2012 Ram 1500 with the HEMI and was wondering if there is a way to tell when the MDS is 4 cylinder mode. As I understand it, the ECO symbol is nothing more than an indicator of light throttle and has no ties to the MDS. I'm switching over from a Chevy that had a indicator that let you know if you are in V4 or V8 mode, and I really liked knowing what the motor was doing.

You are understanding it correctly. At least with the Rams, the transition from V8 to V4 is not as bad as on the Chevy's. I drove a Tahoe as my company car for 6 months and was dramatic. Maybe because of the 5.3 vs the 5.7, I'm not sure.

Trupiano said:
When it goes into ECO mode, that's the MDS kicking in. When you see that ECO indicator light, that's the MDS. You can also hear the difference like the others have said.

Sorry pal but OP is right. The ECO light and MDS are NOT tied to each other. It just so happens that when you see the ECO light, 80% of the time you are in 4 cylinder mode but there are some times you will see it and all 8 cylinders are firing. It is a "pretty good" indicator but you should know that is not a sure thing. I can get my ECO light to come on with all 8 going. Put yours in Tow/Haul mode where it locks out MDS and you will still see the ECO light. The only way to know is when you hear it.

InspectGWS · Apr 22, 2015

My ECO light used to come on all the time, but when I disabled the MDS with my Diablosport inTune DCX, the ECO light went away and has not come on since...haven't seen it in about 6 months and 10,000 miles...coincidence? I think not...

Squidbilly · Apr 22, 2015

Actually there is a mds light mod. Wire up the led and you can see whenever your mds is on. Found it on Ramforumz.

dtru1222 · Apr 22, 2015

InspectGWS said:
My ECO light used to come on all the time, but when I disabled the MDS with my Diablosport inTune DCX, the ECO light went away and has not come on since...haven't seen it in about 6 months and 10,000 miles...coincidence? I think not...

You are the first person I have seen report that your eco light does not ever activate.

In my two rams and challenger 5.7, the eco or fuel saver light still comes on after disabling MDS.

13Ram1500EXP · Apr 25, 2015

Trupiano said:
Who told you that?

When it goes into ECO mode, that's the MDS kicking in. When you see that ECO indicator light, that's the MDS. You can also hear the difference like the others have said.

My understanding is that The "ECO" is not an indicator of the MDS but only that you are driving in a fuel efficient way.

jon0m0berry · Apr 29, 2015

The ECO icon isn't an MDS indicator. It just says weather your driving efficiently or not. I just read my manual. It said nothing tying the ECO icon to the MDS being on or not. In my manual it's on page 207

jon0m0berry · Apr 29, 2015

That's because the tune just turned the MDS off. It didn't change how the ecu determines what is fuel friendly. That's why the ECO icon never/nor will ever come on. The truck is pretty much telling you its not driving in its most fuel efficient state.

saintsreturn · Apr 29, 2015

I turned off my MDS and the eco light would still come one. I was also running an efficient tune versus a performance tune. The light and MDS are not related. That said, you could be in ECO while in MDS. But that's just good driving.

InspectGWS · Apr 30, 2015

jon0m0berry said:
The ECO icon isn't an MDS indicator. It just says weather your driving efficiently or not. I just read my manual. It said nothing tying the ECO icon to the MDS being on or not. In my manual it's on page 207

Apparently "ECO" light indicates the "FUEL SAVER MODE"...This is from a 2010 DODGE RAM 1500 Owners Manual...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."

From my 2014 RAM 1500 Owners Manuel, page 341...

Fuel Saver Display In Cluster
The “ECO” message is located in the instrument cluster display, this message can be turned on or off. To make your selection, touch the “Fuel Saver Display” soft-key, until a check-mark appears next to the setting, showing that setting has been selected. Touch the back arrow soft-key to return to the previous menu.

and then page 521...

FUEL SAVER TECHNOLOGY 5.7L/6.4L ENGINES ONLY — IF EQUIPPED
This feature offers improved fuel economy by shutting off four of the engine’s eight cylinders during light load and cruise conditions. The system is automatic with no driver inputs or additional driving skills required. NOTE: This system may take some time to return to full functionality after a battery disconnect.

So let me interpret this for everyone who thinks the ECO light has nothing to do with MDS...It has EVERYTHING TO DO WITH MDS - and absolutely indicates that your MDS is engaged...

RCFiddyOne · Apr 30, 2015

Not worth getting into an internet argument over. I just know that if I'm on a level ground at certain speeds, I can feather the throttle in such a way to make the ECO light come on with all 8 cylinders firing for about a good 5 to 10 seconds before the MDS kicks in. That tells me, among other things, that the 2 are not connected. I'm running a muffler delete so trust me, I hear the change from 8 to 4. Maybe my truck is different. Believe whatever you want...

saintsreturn · May 1, 2015

As I mentioned, you could be in Eco while in mds but you can also be in Eco without mds. I turned off my mds and still reached Eco as I was driving in a fuel efficient manner. They relate that way but are not linked 100%.

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InspectGWS · May 1, 2015

RCFiddyOne said:
Not worth getting into an internet argument over. I just know that if I'm on a level ground at certain speeds, I can feather the throttle in such a way to make the ECO light come on with all 8 cylinders firing for about a good 5 to 10 seconds before the MDS kicks in. That tells me, among other things, that the 2 are not connected. I'm running a muffler delete so trust me, I hear the change from 8 to 4. Maybe my truck is different. Believe whatever you want...

I believe my owners manual...

saintsreturn said:
As I mentioned, you could be in Eco while in mds but you can also be in Eco without mds. I turned off my mds and still reached Eco as I was driving in a fuel efficient manner. They relate that way but are not linked 100%.

Most of us have a better chance of being hit by lightning than somehow driving our 5.7L Hemi's in such a fuel efficient manner that the ECO light comes on to congratulate us...

The ONLY TIME the ECO light comes on in 99% of these trucks is when the MDS is engaged...

Here is a little something for the other 1%, the vocal minority, the tree huggers, the DNC, etc...

jon0m0berry · Jun 3, 2015

InspectGWS said:
Apparently "ECO" light indicates the "FUEL SAVER MODE"...This is from a 2010 DODGE RAM 1500 Owners Manual...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."

From my 2014 RAM 1500 Owners Manuel, page 341...

Fuel Saver Display In Cluster
The “ECO” message is located in the instrument cluster display, this message can be turned on or off. To make your selection, touch the “Fuel Saver Display” soft-key, until a check-mark appears next to the setting, showing that setting has been selected. Touch the back arrow soft-key to return to the previous menu.

and then page 521...

FUEL SAVER TECHNOLOGY 5.7L/6.4L ENGINES ONLY — IF EQUIPPED
This feature offers improved fuel economy by shutting off four of the engine’s eight cylinders during light load and cruise conditions. The system is automatic with no driver inputs or additional driving skills required. NOTE: This system may take some time to return to full functionality after a battery disconnect.

So let me interpret this for everyone who thinks the ECO light has nothing to do with MDS...It has EVERYTHING TO DO WITH MDS - and absolutely indicates that your MDS is engaged...

ill try to break this down for you. in the first tid bit you talked about from pg 228 it says fuel saver indicator will appear if mds "ALLOWS" engine to operate on 4 cylinders, or if you are driving in a fuel efficient manner. meaning it can be on (eco mode) while running on 8 cylinders. so eco mode IS NOT an mds indicator......second part comparing a 2014 to a 2010 doesn't make sense. different tuning, and I don't see anything about eco or mds on pg 341. it just tells you how to turn the indicator off.....thirdly on pg 521 it just tells you what mds does, again it doesn't say eco mode will come on while mds is on.

so ill say again, eco mode is only an indication if your driving in an efficient manner. its not an "mds is on" indicator

BlownGP · Jun 4, 2015

I'm glad I have none of this **** on my 09.. I just drive the *** out of it!!!!!!!!!!!!!!!!!!!!!!!

lol

RCFiddyOne · Jun 4, 2015

True dat! but I heard that the HEMI engine blocks where piped for MDS long before Chrysler starting using it. Maybe back in '04, I think.

BlownGP · Jun 4, 2015

RCFiddyOne said:
True dat! but I heard that the HEMI engine blocks where piped for MDS long before Chrysler starting using it. Maybe back in '04, I think.

Well I mean I have MDS, but I don't have any eco lights or MDS lights. Nothing.. haha

MDS does nothing to save mpg anyways.. Just another idiot light for the dash..

QwikKota · Jun 4, 2015

RCFiddyOne said:
True dat! but I heard that the HEMI engine blocks where piped for MDS long before Chrysler starting using it. Maybe back in '04, I think.

I don't see what the block has to do with anything? It should just be all top end and electrical items.

I turned on eco light a second ago, let's see if it keep me from driving like a pizza delivery guy.

jag1886 · Jun 5, 2015

You can tell you haven't owned your truck long. I said the same thing when I got mine. Now after 7 months I can hear it turn on every single time and it blows especially when it's on at 15MPH in the neighborhood.

How to tell if MDS is on or off

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