How to: Default Overdrive OFF modification

[Cobraguy]

I've always been irked that the transmission on Ford products defaults to Overdrive being activated. Since it's not a good idea to let your transmission be hunting back and forth between direct and overdrive while you drive around town, I try and remember to shut it off. However, I usually forget until it shifts into overdrive the first time...then I go "Doh!". I've always thought it dumb you couldn't switch the default around. So today, I did just that...kinda...

First thing I did was build me a circuit with a 555 timer and my breadboard. Although it was fun, getting it all onto a circuit board was going to leave me with a rather large electronics piece. I may be able to design and built the circuits, but making them small and usable isn't my cup of tea. All thumbs I guess!

So I looked up on pegboard and found a couple of TR7 modules there. Perfect! So I programed one up to Feature 17, and wired it up. By the way, Feature 17 isn't on any instruction sheet. You need to go to PAC's website and find it. They won't support it either...but it's still there and very usable. Let me know if anyone wants to try this and needs the programming instructions.

Anyway...here's the module in the first picture after I soldered the supply and trigger wires together. I want it to trigger a pulse 3 seconds after the key is turned on. This does that. It pulses down the blue wire. The shrink wrap on the blue wire is for a diode to prevent 12V from going back into the module when I manually trigger the factory switch. I'm not sure you need this...but it didn't hurt.

Then you go under your steering column. Remove the lower panel and support for access. find the small connector from the OD switch. It's to the side of my finger in this horrible picture. (2nd picture) There are two wires to this connector and you need to tap into each of them.


The Violet with Orange stripe is the power line. It's hot in run. Tap your red lead into this wire. The other wire is Tan with a White stripe. This goes to the ECM and tells the ECM to toggle the OD feature on and off. Tap your blue wire into this wire. Solder an appropriate end to the black wire and fasten it to the green ground bolt to the right of the steering column. Fasten the TR7 module out of the way and your done. (last picture)

Now, everytime I start the car, in 3 seconds, the OD light turns on and I default to no overdrive. The factory switch on the end of the stalk still operates as normal. Just a little something to do on a slow day!

By the way...I have an $800 Fluke meter that does a LOT. But I haven't had it out of the case in months now. I keep fishing out this cheap Walmart meter you see. I think it cost me all of about $10. I bought it when I needed it at my son's house one day and we didn't have one. I use the hell out of it! And I just toss it in the tool box. I don't treat it nice at all. Had it for about 3 years now. EVERYONE needs a meter...and this is about as cheap as it gets. And it works! (if I need very precise measurements, I get the Fluke out...but this one is good enough for 99.9% of your needs)

 

[Fabbed4d88]

My hat's off Cobraguy...you have some serious electrical skills.

 

[kert0307]

Nice idea, think you can figure out how to manually shift the tranny too?

 

[Cobraguy]

Nice idea, think you can figure out how to manually shift the tranny too?

Well, as a matter of fact...

Seriously...I know of a 5R55 that had paddle shifters installed on a Lincoln LS. But I believe it had to come with the Select Shift option to be able to do that.

 

[chance942]

Cobra you do seem to be really good with electronics! I agree also that EVERYONE needs a meter. I'm jealous of your Fluke and enjoy your posts. TIL

 

[Corny1]

My overdrive light is off (doesnt appear) I have to remember to press the button everytime i start the car! Is there a fuse or something to activate this light??

 

[Rick]

Nice writeup I set you up with an extra three months of Elite time.

 

[energie]

i didnt even know that about the overdrive but great write up, thanks! i should try it one of these days. or just remember to even put od off

 

[Scotty J.]

Holy bumps batman! LOL

Good info, I'll have to give this one a shot.

 

[po-po 5.0]

What kind of driving do you do that you feel this is necessary?

 

[Cobraguy]

What kind of driving do you do that you feel this is necessary?

You missed the entire point of doing this.

 

[po-po 5.0]

You missed the entire point of doing this.

Obviously...............which is why I asked. I can't seem to envision a style of driving that would make this mod beneficial. The only things that come to mind are a strictly race-only truck or one that tows heavy loads in the mountains on a regular basis. In which case, you'd probably want a larger truck as opposed to electronics hacking.

 

[Maniak]

City driving where the speed limit is 45mph would be a possible spot for this mod.

Around here (Tucson, Az) the speed limit ranges from 25 to 55, in town. When the speed limit is 45mph or so, the trans will tend to go into OD but if you need to slow down a little or step on the gas a little it will normally drop out of OD. Having the transmission hunt in and out of OD often is hard on the trans. Its better to leave it out of OD in that case.

~Mark

 

[mustangsrus]

wow nice mod !!! learn something new everyday

 

[BobWiersema]

Wow thats a great idea.
Probably the first use of a 555 I have seen in a Explorer.
I'm wondering if something like this can be adapted to the brown wire mod for the newer Explorers. Something like a delay on make, delay on break would stop it from kicking in and out of 4x4.

Bob

 

[V8BoatBuilder]

Awesome write up. I just ordered a TR7 from Amazon, and found the "Bonus Features" pdf on the website. Will let you know how the install goes.

The TR7 is a cool little problem solver - I love it.

 

[wpurple]

Here in CT, I always run with the OD off unless I am on the highway, lots less un-needed shifting.

 

[Explorer Power]

Would it be possible to make a meter/guage that show's wich gear the tranny is in?

 

[Cobraguy]

"Maybe" would have to be my answer. Depends on the trans and how much information you need/want to show. Most automatic transmissions have pressure taps for different gears. It's possible, depending on what your trans has available, to use a Hobbs switch and something like LED's to indicate what gear you are in. It's also possible you could utilize the solenoid controls to trigger a low voltage relay of some sort to do the same thing...or a combination of the two. I'm just throwing things at the wall here, but I'm betting it could be done.

 

[inh]

Very cool, I like this. I'm going to try and design a one shot 555 circuit. Using some creative component placement it should be possible to get the entire circuit not much larger than the 555 IC itself I'll keep you posted.