DIY - Inverting the Overdrive Switch - DodgeForum.com


DIY - Inverting the Overdrive Switch

 
 
 
  #1  
Old 10-08-2011, 06:54 PM
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Thumbs up DIY - Inverting the Overdrive Switch

Credit for this goes to DodgeRam.org, and credit for finding it goes to EndIsNear here on DodgeForum.com.

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For Most 2nd Gen Rams (1994-2000):
It's a VERY easy thing to do... I came up with this one night, and was surprised how simple it is. All you need is a regular accessory relay and some wire.

But first, some info on how the OD switch works. TO turn OD on or off, it requires a pulse of ground, which is what the OD switch does. It is a momentary-contact type switch, and when you press it, it gives ground to the PCM telling it to turn OD on or off. ***FYI, the Ford E4OD and 4R100 work the same way, but just use 12V+ to the PCM instead of ground.
So basically, all you need to do is give the PCM a ground pulse when you start the truck. Standard relay terminals are:
  • 85: Coil 12V+
  • 86: Coil ground
  • 87: Normally open
  • 87A: Normally closed
  • 30: Common feed
Wiring needed:
  • Connect the relay coil (pin 85) to the starter relay wire - dark blue with a yellow tracer in the steering column wiring harness.
  • Connect ground to pin 86.
  • Connect ground to 30 - this will be the ground feed for the pulse to the PCM.
  • Connect a wire from 87 to the OD wire - orange with a white tracer.
When you turn the key to the START position, it will trigger the coil in the relay, and give ground to the OD switch wire going to the PCM, thereby locking out OD, until the button is pushed. Basically, it would be like holding the OD button down while you start the truck. It works. Try it.



For 2001 Rams:
For the 2001s, the starter relay wire is yellow and it runs through the clutch in switch which is just a jumper on the AT's. I hooked the positive of a 24V relay to the wire on the clutch in switch. The negative to ground and then jumpered the ground to common on the relay. Then the orange with white stripe wire coming from the OD switch is tied to N.O. on the relay. At start up the relay activates and gives a ground pulse to the OD switch turning it off. Just pull off the knee plate under the dash and everything is right there. Plenty of room to mount the relay too.

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Source:
http://dodgeram.org/tech/mods/transm..._inverter.html
  #2  
Old 03-06-2017, 02:53 PM
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Default DIY - Inverting the Overdrive Switch

I finally got around to doing this mod, it was low on list. I have a few tidbits to pass along...

My truck is a '99 but it had the yellow wire , not the dark blue with white tracer. While I was checking to make sure it was the correct wire, I was checking voltage. I had some strange readings, 12v on the yellow, with ignition on, but in "start" AND in "R, D, 2, 1." The voltage dropped to zero in "P, N." This was obviously because it was being grounded through the start relay and grounding the signal. But why the 12v in the other positions, is it going to cause it to switch in and out of OD when shifting? No. It must be some vague transient voltage. It works fine in my truck.


Also, the or/wh wire and a blk/gr wire are all by themselves. Mine were on the driver's side of the column, twisted like cat 5 cable, in black shrink tubing. Those two go back to a 2-pin connector clipped to the steering column. These are actually the only other two other wires you want, the or/wh is the signal and the blk/gr is a ground (which I used for my relay and signal ground).

So,

Yellow wire is "start" positive 12v to the relay coil
Blk/gr is ground for relay coil AND OD signal terminal on relay
Or/wh is signal out to the PCM from the relay






Mods- feel free to add this to the DIY thread on this that already exists...
 
 
 

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