Stand by for updated info. The wire which I thought was to the MDS was actually for the VCT.

If you do this and break something, or if any information posted is wrong, it is not my fault.

I got under the hood finally and tried the 2006+ MDS light mod. It does not work, the wires must be different. After tracing the some wires, I found that there is a harness that runs underneath the intake manifold and into one of the MDS harnesses. I think it is a lifter controller??

I just took a solid core wire and pushed it into the back side of the connector. I know this is not the preferred method, but it allows me to take it off when I want to go to the dealer for something. I don't want them to ask me any questions.

Check out post #16 to see the voltage. When MDS is off, meaning running on all 8 cylinders, it runs 6 volts. When MDS is on, there is .3 volts.

First. Loosen the worm clamp and pull off the intake tube.


Second. Slide the red button out and then press down the black tab shown by the yellow arrow and pull the connector from the sensor. Then, loosen the worm clamp and remove the intake tube and set aside.


Third. Pull off the engine cover. It just pops off, there are no screws or bolts. Then, find the blue wire in the connector shown. The wire goes underneath the intake manifold into one of the MDS connectors. I pushed a solid wire into the connector shown, on the back where the blue wire enters it. I did not solder or cut anything. I want this to be easily removable.


This is a picture of the wire in the connector.


Fourth. I drilled a small hole and put an LED in there. I wired one side to the LED and grounded the other side. This panel pops out after the three screws are removed.


I ran the wire through the nipple underneath where the big bundle of wires goes through the firewall. I poked a small hole with my knife.


I grounded the LED with this bolt.


Here is a quick video. The light comes on when on all 8, it is off when on MDS is on.


Lastly, good luck working on this thing.

 

Why not just look at the EVIC?

 

While this would be ideal, the trucks built on or before 10/08 do not have a fuel saver light.

 

Doh!!

 

Its okay. It gave me a chance to get under the hood and really look around. There is so much room in the engine compartment of the truck.

 

I toyed with adding a similar light to my wife's Magnum. But I figured it wasn't worth it for her car.

 

It is pretty easy once you find the right wire. Look under the intake manifold, if you can, and find the connector underneath that connects to something in the lifter valley. Follow it out and you should see another connector you can tap into.

 

I'm kinda glad mine doesn't have a light, it seems that it would be kind of annoying.

Enlighten me, why would I want the light? (No pun intended )

 

MDS comes on when exhaust gets quiet!

 

To try to maximize gas mileage and just for curiosity.