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Discussion Starter #1
This is How to add a MDS light to your dash​

This will work for the 2006 - 2008 Dodge Ram as long as you have MDS​

The light will come on when the MDS is active (running on 4 cylinders)​

What you will need:
  1. Green LED from Rat Shack 276-271
  2. soldering iron
  3. rosin core solder
  4. drill with 1/4" drill bit
  5. about 10' of wire 22 ga
  6. wire stripers
  7. wire terminal crimpers
  8. a 1/4" ring terminal for 22 Ga (red)
  9. Inline wire tap for 22 ga (red)
  10. pliers to sqeeze splice
  11. 2" of shrink tube for the 22 ga wire
  12. 1/4 x 1 and 1/4 bolt and nut



First thing is to find the Brown/Orange strip wire coming from the C3 connector of the PCM located on the fire wall behind the air filter. The top connector is C1 and C4 is the bottom one. The wire bundle from C3 comes over to the fender and up, which gives you good room to pull the BR/OR wire out. Using the wire tap splice in the wire your going to run.



Now run the wire along the top of the engine compartment and I ran it through the existing tie straps that hold the existing bundle.



Then I poked it through the firewall through the grommet that has the hood release cable but you can go through where ever you want.

\

I used a small plastic plug that is in the drivers side knee booster to mount the light in. I could pop it out with out removing the whole panel. Drill a 1/4 hole in it and you might have to ream it a bit and debur. Mount the led and then side a 1" piece of heat shrink over the wire and then solder the red led lead to the wire. Then solder a short lenght of wire to the black ground lead. Slide another heat shrink tube over that solder connection and shrink with heat, and do the same to the red wire tube. I like to use a portable butane powered soldering iron for this kind of work and as a added bonus, you have a hot exhaust from the iron to shrink the tubing. Now crimp the 1/4' terminal end on the ground wire. The 276-271 LED has a internal resistor to make the install easier. If you hook it up backward you will not hurt a thing, It just will not light up.



Reinstall the plastic panel plug and then go under the dash and attach the ground. I used a 1/4" hole in the large cast aluminum part that supports the steering column and the 1/4" nut and bolt.



You can add a small toggle switch inline to turn off the light. It doesn't matter which wire you put the switch in. Since its mounted so low it doesn't shine in my eye and the steering wheel blocks it for the most part. I have been using it for a few days and here are a few observations - MDS will kick in at a slow speed, accelerating from a stop slowly it will come in at about 10 mph and I could accelerate to highway speed without it dropping out but you better not have anybody on your bumper. At 70 mph it will still kick in but I haven't tried it at any faster speeds yet. It will come on and stay on when you are decelerating or coasting. If you have a heavy head wind it will not come on to often.
 

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2010 SRT8 Challenger
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this is freaking sweet...wanna come to ohio and install another?? :D :D
 

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I like the Mod.... I have been wondering when my MDS is kicking in....Just have one question..... How important is it to use that specific led from Radio Shack.... Thanks for the write up I think im going to try this this weekend....
 

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Discussion Starter #4
You can use any led but that one had a internal resistor so it made the install easier and it had a low profile. If you use a plain led you will need a external current limiting resistor.
 

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Cool.... Thanks for the info.... I like the one you used because it is low profile, just wanted to check before I went to radio shack and the didnt have that one..... Thanks again....
 

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Just installed mine and it works great... went smoothly... thanks for the info!!!!
 

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Milo
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Sweet !! Thanks for the info.
 

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can you use any of the 4 MDS control wires at the PCM? also does this wire produce 12v when activated? if not what voltage does it produce? the reason i ask is i know RS sells LED's that dont require 12v. some 1v ro 3v. i have a bunch of 12v alarm LED's that i could put to use. thanks in advance.
 

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Discussion Starter #9
piper18 said:
I used a small plastic plug that is in the drivers side knee booster to mount the light in. I could pop it out with out removing the whole panel. Drill a 1/4 hole in it and you might have to ream it a bit and debur. Mount the led and then side a 1" piece of heat shrink over the wire and then solder the red led lead to the wire. Then solder a short length of wire to the black ground lead. Slide another heat shrink tube over that solder connection and shrink with heat, and do the same to the red wire tube. I like to use a portable butane powered soldering iron for this kind of work and as a added bonus, you have a hot exhaust from the iron to shrink the tubing. Now crimp the 1/4' terminal end on the ground wire. The 276-271 LED has a internal resistor to make the install easier. If you hook it up backward you will not hurt a thing, It just will not light up.
You can hook to any of the control wires, the one I picked was just the easiest to get to since I have the stock air intake. They are 12 volt when active. If you use a plain LED then you will have to add a external current limiter to keep the LED from burning up on 12 volt but if you use the one listed, its already there.
 

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Premium Member
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RedHemi07 said:
Just installed mine and it works great... went smoothly... thanks for the info!!!!

SWEET! Any pics? Where did you mount the LED?
 

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Hi, thanks for your post, very useful to understand what to do...
I have a 2006 Durango Hemi with (I suppose) MDS. I would like to do the same thing. Could you tell me how you found the right wire for your Ram ? Do you think my Durango has the same color patern as yours ? My PCM is not easy to access, I think I will have to remove the battery and the tray.
Thank you,
Dominic
 

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Great View
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Discussion Starter #12
You will have to find a shop manual and verify the wire color for the durango. You have 4 wires to pick from.
 

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Just installed mine today, works sweet. :rck: Thanks for the write up.
 

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grunt
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Sweet Write-up Will Do Mine Soon. How Did You You Do Your Tailgate?
 

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I did mine last week,work great!! it's real nice to know when it is actually activating the MDS. thanks for the right up nice job. :rck:
 

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253 Posts
sweet! i'm doing this for sure.

now, do a write-up for us on how to hardwire some kind of toggle/switch to manually engage the MDS system without letting it switch back to 8 cyls unless the switch is manually turned back off. :)
 

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Remeber 9/11
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324 Posts
Thanks for the write up! I installed mine last week. That little light explains alot. The little surges and rpm jumps are from the MDS! I was thinking something was wrong with the truck. I can see why some on this board want to deprogram MDS.
 

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In my Ram, I don't see that wire coming off of the C3 connector, I actually only see the BR/OR on the C2 Connector, can somebody help me out?
 
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