Wiring the 42RLE overdrive for off by default

[Maso]

Like I said, it's all done and running fine. This is on a export RHD TJ, so if something looks strange, that's why. No longer do I have to press the OD switch every time I start up. I managed to pull the wires out of the connector, just had to insert a pin in and lift up a little tab that holds the wire in. The pin worked, but something a little bit stronger would have been good as I bent the pin trying to lift the plastic tab, it did work though. Then I stripped some of the wire bare and soldered on the ones from the relay. I didn't want to cut the wires. Then I slid two pieces of heat shrink over the joins and inserted the wires back into the connector.
I have put the relay in behind the glove box since there was a tab there I could bolt the relay bracket to.

 

[LakeBeard]

this is great, I'm going to do this tonight, one question I have, does the white / green reverse wire get tapped into or cut and ran over to the relay? probably a dumb question, but wiring makes me nervous...

 

[Matt1964]

Maybe I'm stranger than I thought.

I always feel like a WWI fighter pilot when I get in my Jeep.

I say "Switch off?" and then yell "Contact!" when I turn the overdrive off.

 

[Onewing]

Tapped into. But you need to verify the wire, mine is purple with black stripe. Of course I didn’t at first but it just takes a few minutes to pull the tail light to see what color feeds the backup lights.

 

[Maso]

this is great, I'm going to do this tonight, one question I have, does the white / green reverse wire get tapped into or cut and ran over to the relay? probably a dumb question, but wiring makes me nervous...

I just tapped into it. It was the white wire with green stripe. 2006 TJ. It's been working well since I done the mod.

 

[Hoboscratch]

Just did this. Awesome mod. Can confirm my reverse light wires were purple/black too, on my ‘04

 

[pagrey]

Although it isn't too important I think because you are using the O/D light to operate the circuit if you turn the O/D back on so the light is off and shift into reverse at anytime it will again set O/D to off if that makes sense. The circuit will only trigger when the light is off, once it is on the relay doesn't do anything. Once you manually turn the O/D back on then the circuit is enabled again and will work when you put it in reverse. Somebody that has done the mod might test this but that's how it "should" work.

(it is very clever to use the O/D light output from the TCM to operate the circuit by the way, you are also applying a +12V signal to a TCM input that is expecting a ground signal whenever the Jeep is shifted into reverse with the O/D off but that's probably not an issue)

 

[LakeBeard]

Although it isn't too important I think because you are using the O/D light to operate the circuit if you turn the O/D back on so the light is off and shift into reverse at anytime it will again set O/D to off if that makes sense. The circuit will only trigger when the light is off, once it is on the relay doesn't do anything. Once you manually turn the O/D back on then the circuit is enabled again and will work when you put it in reverse. Somebody that has done the mod might test this but that's how it "should" work.

(it is very clever to use the O/D light output from the TCM to operate the circuit by the way, you are also applying a +12V signal to a TCM input that is expecting a ground signal whenever the Jeep is shifted into reverse with the O/D off but that's probably not an issue)

Yup, that's how mine works.

 

[pwrtstdan]

I added the relay to my 2003 TJ Rubicon today. My wire colors were a little different:
-Purple/Black is my backup/reverse wire color so that went to pin 86.
-Dark Green/Light Blue went to pin 30.
-Orange/White went to pin 87 (I don't have the blue wire)
-Black went to pin 85 (grabbed the ground from the overdrive connector)
I have auto dimmer rear view mirror so I used the backup/reverse wire that goes to it and tapped it on the top of the dash at the right side.
It works great.

 

[pwrtstdan]

Oh...and I used @Maso method of removing terminals from connector which is a pain if you don't do it right. I used an eyeglass screwdriver, the tiniest one. You want to slide it down the top of the metal of connector to push up on the plastic tab. I don't know how @Maso did it with round pin...I had to use a flat tool.

 

[pwrtstdan]

Although it isn't too important I think because you are using the O/D light to operate the circuit if you turn the O/D back on so the light is off and shift into reverse at anytime it will again set O/D to off if that makes sense. The circuit will only trigger when the light is off, once it is on the relay doesn't do anything. Once you manually turn the O/D back on then the circuit is enabled again and will work when you put it in reverse. Somebody that has done the mod might test this but that's how it "should" work.

(it is very clever to use the O/D light output from the TCM to operate the circuit by the way, you are also applying a +12V signal to a TCM input that is expecting a ground signal whenever the Jeep is shifted into reverse with the O/D off but that's probably not an issue)

So when you start the Jeep, pin 30 = ground. The instant the relay closes, due to voltage from reverse/backup tap, pin 87 connects to ground via pin 30 and toggles OD to OFF. Pin 87 only sees ground for milliseconds until the TCM sends voltage to pin 30. Pin 30 then always has voltage so it can't toggle OD again until the ignition is cycled. Right?

 

[pagrey]

So when you start the Jeep, pin 30 = ground. The instant the relay closes, due to voltage from reverse/backup tap, pin 87 connects to ground via pin 30 and toggles OD to OFF. Pin 87 only sees ground for milliseconds until the TCM sends voltage to pin 30. Pin 30 then always has voltage so it can't toggle OD again until the ignition is cycled. Right?

Sure, but whenever you put the Jeep in reverse with the O/D light on pin 30 is connected to pin 87 the whole time. It's no big deal but that pin is designed to be pulled to ground with a simple switch. You are using the relay to short the light output from the TCM to the switch input and hoping it doesn't blow up. It's not just milliseconds, you are connecting those two TCM pins the whole time the Jeep is in reverse. Obviously it works, cool. You can toggle O/D again. Just turn O/D off so the light is off and shift into reverse, the light will go on. Think of it as a one way latch and pressing the O/D switch on the dash resets the latch.

 

[pwrtstdan]

Sure, but whenever you put the Jeep in reverse with the O/D light on pin 30 is connected to pin 87 the whole time. It's no big deal but that pin is designed to be pulled to ground with a simple switch. You are using the relay to short the light output from the TCM to the switch input and hoping it doesn't blow up. It's not just milliseconds, you are connecting those two TCM pins the whole time the Jeep is in reverse. Obviously it works, cool. You can toggle O/D again. Just turn O/D off so the light is off and shift into reverse, the light will go on. Think of it as a one way latch and pressing the O/D switch on the dash resets the latch.

Yep. Not ideal to expose that pin to voltage when it is only expecting a ground. The ECM must be protected somehow. I've been using it now for a week a love it. In my opinion this is the best value upgrade for a TJ with a 42RLE. Cheers to @AndyG !

 

[Hoboscratch]

Sure, but whenever you put the Jeep in reverse with the O/D light on pin 30 is connected to pin 87 the whole time. It's no big deal but that pin is designed to be pulled to ground with a simple switch. You are using the relay to short the light output from the TCM to the switch input and hoping it doesn't blow up. It's not just milliseconds, you are connecting those two TCM pins the whole time the Jeep is in reverse. Obviously it works, cool. You can toggle O/D again. Just turn O/D off so the light is off and shift into reverse, the light will go on. Think of it as a one way latch and pressing the O/D switch on the dash resets the latch.

I’m confused. Are you saying this is not ideal or ok? Just looking for clarification, thanks!

 

[pagrey]

I have not tested this so am not really in any position to say either way. I haven't even heard from anybody confirming that I even have a clue how it works with respect to it latching. I will say without measuring the current draw on the orange and white wire when you apply power I wouldn't use this on a daily basis on my Jeep. If the current is low, specifically lower than when the circuit is pulled to ground I wouldn't worry.

 

[LJRubicon]

Mine already defaults to off so the PO must have done this mod

 

[AndyG]

Mine already defaults to off so the PO must have done this

Cool...If you ever can get some idea of how he did it it might be good to know there could be a better way to do it

 

[Honeybadger]

Just did this on a 2006 sport 4 liter I6 recently purchased for my daughter. Reverse wire in this rig is white w/ light green. Pre loaded relay with some extensions, connnected Green & Blue just behind O/D button & to reverse wire on drivers side.

 

[AndyG]

Just did this on a 2006 sport 4 liter I6 recently purchased for my daughter. Reverse wire in this rig is white w/ light green. Pre loaded relay with some extensions, connnected Green & Blue just behind O/D button & to reverse wire on drivers side.

How do you like it -

 

[Honeybadger]

How do you like it -

It awesome, pretty much did this so my daughter doesn’t have to think about it every time.
Been driving my manual for years so when I picked up this auto Jeep I had to get used to the shifting patterns. Didn’t make sense to have O/D ON all the time and I don’t really like the way it feels driving around town in that mode.