Overdrive lockout switch? (w/Smarty)
 

I am a new member of the Smarty Jr club and I just realize since I've reprogrammed my ECM, that I have lost the ability to disable overdrive with the tow/haul switch (TSB 21-006-07 ). And of course I paid my dealer to install this update for me [verymad] [verymad] [verymad] !

Since I am hoping to keep the Smarty and I frequently tow (heavy!!), I need to find a new way to keep the transmission in 3rd gear. I've already taken a look at the ATS Overdrive Cancel Switch and the OD Lock-Out from BD, but...

It seems to me that making a simple OD selector switch is similar to doing the mystery switch (which I already have). Can I simply install a switch in the wire that goes to the 3-4 solenoid (pin 6 on the trans' connector)?? and then ground the wire from the ECM (through a 33ohm resistor) ??

Anybody done this? Got a schematic?
Thanx
-Mark

Seriously?
Nobody has made their own OD lockout switch?

Nope, you have to feed 12V thru to the ECU or it will see a failure. The ECU monitors the circuit for resistance between 5 and 100 ohms. If it is not in that range it throws codes and goes to limp mode. The only way to complete the circuit is 12V with the load taken out so it does cook the ECU.

wait... i just read this again slowly... you are running the smarty jr and lost the ability to lockout od..???...
mine is an 06 model that had the ability to run without od from the factory..

His is an 05. They came with Tow/haul mode and no OD lockout. The dealer reprogrammed it so it would act like an 03-04.5 truck with only OD lockout. I would get the BD kit. Rarely do I need to lock out OD, but when you need it, you need it. I would like to have both functions like the 06-07, but don't.

Thanks for the feedback so far...

Based on what I'm seeing in the wiring diagram supplied with the ATS OD lockout (below)... it looks like I can splice into the 3-4 solenoid wire and install a single pole switch that will prevent the transmission from shifting into OD and add a wire that supplies the ECU with 12V (through a 33 Ohm resistor) to keep the ECU happy.
http://www.simulationfx.com/odcancel.jpg
Anybody else done this?

I do think that the product from BD is interesting, but their operation method (single-tapping & double-tappong the tow/haul button) seems unpredictable, plus it costs over $200.

As Spooler said, when I need 3rd gear, I NEED it. For example; Towing heavy and descending a long grade... with the exhaust brake ON but the transmission in OD there are insufficient engine revs to maintain a safe downhill speed, but In 3rd gear it works great. Same goes for climbing a grade in 3rd with the TC locked.

The single tap and double tap are exactly how the 06' and 07' trucks work.

Uh... not "exactly".

The '06-'07 trucks have three options that you can scroll through in the following order: STD - TOW/HAUL - OD OFF

The BD controller works as follows:
To activate, press the TH button twice in rapid succession.
To execute a downshift and hold your transmission in 3rd while driving in Normal Mode, press the TH button once to turn on the factory TH light and cause a downshift, and then press it twice more to activate the OD cutout.
To execute a downshift and hold your transmission in 3rd while driving in TH mode 4th gear, press it in twice to cause a down shift and lock it into 3rd gear.
When you wish to execute a 3-4 up shift from either mode, simply press the TH button twice and you will deactivate the OD cutout and still be in the Same TH mode (on or off) but your ECM will then perform an up shift.

If you think the BD controller is unpredictable, just wait until you try to implement what you suggest. [laugh]

When you burn the OD sense circuit out of the ECM and the truck goes into permanent limp mode that $200 is going to seem mighty cheap. ;)

When you try to control the OD circuit without properly timing and controlling the lockup circuit and the trans stays in OD locked when you try to stop, you might have to re-think predicatability and cost.

The 33 ohm resistors we use for a lockup switch are all installed on the sense side, past the load. There is little current there so a 1-2 watt resistor works fine to route to ground and actiavte the circuit. If you tried to hook the 12 volt supply to the trans thru the resistor to ground it would just melt it, probably after cooking the ECU sense circuit. With 12 volts and that circuit you would need a .1 amp source to NOT blow things.

Second problem you will find is you cannot activate an OD lockout until the TC is unlocked in most builds. It just won't work so you also have to control the lockup circuit the same way, isolate the the lockup circuit and drop it before donwshifting. You will tapping the TH button and flipping switches in sequence in time contrained manner just to get the basic functionality.

Buy the OD lockout controler from whoever you want and spend the $200. In the long run it will cost you less and be much easier to make work consistently.

Thank you no_6_oh_no
I most definitely don't want to damage my ECU! That is why i am asking questions first [redface]

So are you saying that the Overdrive Cancel Switch that ATS sells does not work? Their wiring diagram doesn't show a connection from the 12V supply connecting to ground... From what I can tell, that's a single pole switch and the ground is for the lamp that's in the switch.

I took a look at the installation manual for the BD controller and it doesn't appear that it has the ability to unlock the TC before de-energizing the 3-4 solenoid. Hmmm......

Mostly I wish that MADS would give me the option to have the same OD lockout that my dealer enabled.

No, both the ATS and BD OD cancel switches work fine. Its how they are activated that is the key. The double tap in 2 seconds on the TH button does that.

Anytime you tap the TH button on the shifter stalk it puts the ECU into a 5 second cycle. Since it is almost always in OD, the first tap cycles the TH which will tell the ECU to drop lockup then OD, then the second tap in 2 seconds tells the OD controller to activate its circuits which bypass the ECU sense wire from the OD solenoid so it won't engage and feed a false signal to the ECU so it thinks it is engaged.

The internals in the controller box handle the current step down so it doesn't screw up the ECU and the timing lag that is needed for the ECU to disengage lockup and OD so it can do its job.

If you slow tap the TH button its just like normal, the ECU drops lockup then OD, activates the TH algorithm then proceedes to run its altered shift pattern. If you double tap the button in a 2 second period it does the same thing with the additional action of activating the OD lockout. The box is tapped into the circuits needed to tell when OD is dropped so it can do its thing.

Thats the thing that gets dicey with a manual system, you have to get lockup and OD dropped before you can activate the lockout or it just won't drop it or it goes into limp mode. You still have to tap the button then hit your switch in the 2 second period AFTER OD has been disengaged to activate a home made lockout. It gets tricky getting it right when you need it becuase of the timing. Thats what missing is the automatic delay and sense of when to switch circuits for lockout.

It works much better if your locking out OD from a stop then activating it when needed. Even then, disengaging OD in a manual system will immediately force a locked to locked OD shift because there is cycle to drop lockup. In a built trans that is not a big deal, BAD idea without a billet input and beefed up TC.

Seriously, unless your just set on perfecting a home made system and really want to test your reflexes, get an OD lockout controller. The home made system is novel for a while until you miss the timing sequence when you NEED it, then its just annoying. [coffee]

Here is another thing to think about, the programmed OD lockout does not give you the TH algorithm. With the BD controller you have a choice of locking out OD and using either TH or regular mode. It all depends on WHERE you activate the lockout. Really, the switch back to just OD off was a cheap fix Dodge did to stop the complaining. I wanted the ability I have now which is even more than the 06+ trucks so to me it was well worth the cost. One of the cheaper mods I have done to the trans. :)

Again, thank you no_6_oh_no. This is very helpful stuff!

What about the ATS switch? It doesn't interface with the button on the shifter-stalk (or associated wiring) at all. How does it work?
Click here to see the ATS installation manual...

I have no idea how the ATS piece works. From the pictures and wiring it will NOT work on an 05 without issues. That doesn't mean the instructions and diagrams are correct for the product either. I have seen incorrect info posted on their downloads for install docs.

The BD box not only taps the OD circuit but it also taps pin 13 on the ECU B connector which is the TH momentary button interface. I seriously do not know how the ATS box works or can work as shown becuase I had the same typer of setup and got codes from it. Maybe there is more in the switch than what is shown.

The BD unit is proven and reliable. Some of the ATS stuff, wellll, lets just say the final results are less than stellar. ;)

Quick update:
I installed the BD Overdrive LockOut and it works as advertised. Definitely worth the $200 price tag!
It's not as simple (operationally) as the factory mod was, but on the other hand the tranny sure shifts nice in tow/haul mode.
Thanks for all the advice!

It may not be as simple as the OD off, but, the bonus is you get TH in 1-3 with OD locked out. Towing at speeds under 60 mph with the better shift and lockup algorithm is a huge bonus. :)