If there is a thread on this already kindly direct my noob behind to it.

I would like to know when the MDS is on. I am thinking that the MDS cuts the spark to the four cylinders that are deactivated. If this is true, can a splice a wire into one of the coil wires with a NOT gate and then run to a LED that I can place in the dash? I want the LED on when the MDS is on.

Or, can I simply splice into a coil wire and run it to an LED? So then the LED would be on when all eight are up and running and off when the MDS is off.

I know an LED draws only a little current, but I want to make sure this won't screw anything up.

If I am way off base please be gentle!! I know from other threads I may not be the only on interested in this.

 

https://dodgeforum.com/forum/diy-do-...tor-light.html

I found this thread. I wish we had a service manual to make sure the wires on the 2008 and 2009 are the same. I don't want to randomly splice with out knowing for sure.

 

I believe can field this one for you. BY a NOT gate I assume you are referring to an inverter. An Op Amp, TTL or CMOS gate can handle the logic, unfortunately nether one will survive direct connection the coil circuit. To do so would require level translation and you will still be dealing with the HV component of signal path - not the place to play. By contrast, Power budget (Current consumption) is at the bottom of your design list. The place to do this with is somewhere in the ECM areana since there will likely be a logic flag accessible via *some* control port at MDS activation. This flag begins somewhere in software and source code is likely never to be released. Decompiling firmware/software is way beyond the realm of a hobbyist trust me. Now, if you can map external control lines that reflect for MDS then the use of a buffer gate and/or Op Amp to LED is a relatively easy chore.

 

I forgot one other point here - the MDS activation/off cyle may occur in very short intervals (mS) rendering the inherent lag of a simple visual state indicator of little value. Thats why its likely Dodge did not employ an indicator? Just speculation on my part.

 

This is why I love forums. Thank you for the information. I threw the coil wire out there but didn't know for sure.

I am going to do some more research, if I can find anything, on the MDS.

 

Just for clarification, I did mean the wire/wires that feed the coil, not the spark plug wire. There is a coil per cylinder.

 

My bad, I misunderstood. I'm sure you will verify the voltage levels. If you find info on the MDS let us know. I would like to get into the firmware to change the computer display. Instead of the Ram's head logo I could put my own, something like that. A rainy day project..........