Inverting OD Switch - DIY

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kpd12

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Overdrive Switch Invert Mod



Edit: I should hope it goes without saying, but I accept no responsibility for anyone screwing up there vehicle while attempting this modification. It worked for me and although it's only been a couple days, I have seen no adverse affects from completing this simple task.

Our Rams with a 46RE transmission and possibly other electronic transmissions, require a ground pulse to activate and deactivate the OD. From the factory the OD is ON at startup and to deactivate or turn off the OD you must push a button on the end of the gear shifter. By “inverting” the OD switch on a 46RE transmission the OD will be turned off at startup. This can be easily done by adding a relay between the starter wire and the OD wire which sends a ground pulse to the OD system at the time your truck is started. I decided to complete this mod and have done a very brief write up as to what I did.







What I used to perform this mod:

30/40 Amp Relay with wiring connector (so as to not need a bunch of female connectors and to make a cleaner looking install)

16 gauge wire

Wiring butt splices ( I used a combination of splices with heat shrink already attached and the plastic covered kind that I then covered with heat shrink)

A spade connector for the ground connection

Heat shrink tubing

Zip ties

Wire loom



I began by labeling the wires on the relay with tape as follows:



Pin 85 (red wire on my relay) – Starter

Pins 86 (yellow wire) and 30 (black wire) – Ground (taped these wires together)

Pin 87 (blue wire) – Overdrive)







I then removed the knee kick panel under the steering wheel. All the wires needed to splice into are located here, as well as room to mount the relay.



Starter Wire 2.jpg



You will then need to locate the starter wire located in the ignition harness (red arrow above is pointing to harness). On the 2001 Ram the starter wire is a yellow wire, but I believe on older models this may be a different color.



As I have an aftermarket alarm, with a starter kill feature, my wire had already been spliced into. The red arrows below are pointing to the yellow starter wire in the ignition harness after I had already spliced into it for my alarm starter kill. I just connected the red wire from my relay that I labeled “starter” and is connected to pin 85 to this wire using a butt splice.



Starter Wire.jpg



I then located the OD wire which is an orange wire with a white tracer. There is a connector on the left side of the steering column where you can locate this wire. The red arrow below shows what the connector looks like. You will need to unplug this connector then remove a portion of the black plastic shielding that houses the wire you will need to splice to. In the picture below I have already begun removing some of the black plastic protecting the wiring.



OD Wire Connector.jpg



Below the red arrow is pointing to the orange and white overdrive wire. I spliced into this wire with my blue wire (pin 87) attached to the relay and replaced the black plastic that I removed with a short amount of small diameter wire loom



OD Wire.jpg



I attached an additional amount of wire to the black and yellow wires (pins 30 and 86 respectively) that I already connected together, on the relay and using a spade connector attached this to a ground location under the dash.



I then zip tied the relay to a metal portion of the dash sub frame and added a small amount of wire loom to protect the relay wires and to clean up the appearance.



Relay Location.jpg



The OD light should now be on at startup and the OD off, until the OD switch button is pushed.



Hope this helps anyone interested in completing this modification.
 
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kpd12

kpd12

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Driving at lower speeds, towing heavy loads and driving up certain grades can cause erratic upshifting and downshifting. I personally see erratic shifting due to cruising speeds and grades and completed the mod in an attempt to alleviate them and hopefully extend the life of my trans.


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Merc225hp

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I forgot about this mod. Moved it to the top of my list as its the next thing I do after I start the truck and put it in N or D.

Thanks for the DIY and nice work.
 

russellle

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Maybe another addition to this would be to reverse the OD lamp so that it comes on when the OD is back on. That would prevent you from burning out your OD lamp early and having to pull out the cluster to replace it. Just a thought.
 
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kpd12

kpd12

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I know this is an old thread, but since I started it, I'm awakening it...... Since completing this mod, I haven't used my cruise control. Yesterday I put another couple hundred miles on her and tried to use my cruise. It didn't work, although cruise power did turn on. I know this, as the "cruise" light on the dash lit. Just for giggles, I disconnected the relay for this mod this morning and wala, cruise worked. Apparently, this is a limitation of this mod and I will have to research this to see if it's resolvable. Not sure if others who have completed this have seen the same problem or knew about it ahead of time, but I did not. Of course this isn't a huge problem, but still would like to have cruise as an option on long trips. I'll update this thread if I find a way around this issue.......


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01rammer1500

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What is the difference between this mod and pressing the button on the shifter?

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dodge dude94

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It's off automatically when you start the truck.
 

Gr8bawana

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Why bother? It might take half a second to push the button to lock out the overdrive, big deal.
 

Dan98

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I'm 5 years late but thanks for the info I converted my 98 back to carb still running the 46re with toggle o/d and lockup.
 
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