Overdrive in automatic in cold weather?
 

Curious if anyone has come up with a bypass to the transmission temp sensor or a way to trick it into thinking it's always warm. Not a fan of automatics but going to be my winter vehicle. And time to time driver in the summer. 02 explorer v6 with 260k miles on it. Looking to squeeze out a few extra mpg during summer. I have a short commute so waiting for trans temp to reach 110° is 1/4 of the way there. I still manage 22 mpg but would easily reach 24 with some earlier jumps to OD. Going to get an upper grille block going as well shortly.
Hate filling this beast up since I drive a 14 Cruze eco normally and break 50 mpg regularly in warm weather.

Either do a manual TCC lockup or do a pan mounted heater to warm the fluid up.

Pic coming soon for TCC Lockup wire info!!

http://i1076.photobucket.com/albums/...psqy1ndxtk.jpg

As you can see, Pin 14 is where to start

Wiring is Violet with a yellow tracer

How would you go about bypassing it. I've seen some shady looking creations. Would like to do something easily removable. Would be in just for summer driving.

I finally got to double check the diagrams, looks like all you have to do is ground the wire I told you about and it will lock up the converter, it may be easier to find the wire at the computer and then run it to a switch and ground it, I would also suggest an indicator to let you know that it is engaged

I'm just trying to.figure out where to do.this exactly. Started thread on a whim someone else had played with the torque converter lockup. I was thinking I just need 2 wires to a switch. How does the system ground itself out unless I completely misunderstand. I'm terrible with wires.... probably from being electrocuted a lot lol.

Their may be a reason lockup is locked out when the fluid temperature is below a certain temperature.

That would be to warm up fluid...from my understanding the fluid has to hit the set temp they want. All to achieve smoother shifting and warm the vehicle up to reduce emissions.
I drive with an extremely light foot. Rough shifts shouldn't be an issue which is what the main concern seemed to be on another thread I viewed. I just want it to lock up during summer. Winter which it will be driven more for safer travels particularly​. I would leave it to adjust itself most likely. At least until up to operations temp. Current driving conditions for my time of day are around 40-60°. No real issue with fluids at these temps. Just my thoughts for that. When I hit winter and have -20° and lower again that's another story.

I would be tempted to add a resistor to the temp circuit to trick the computer. This is the chart out of a 2002 4t40 manual. I would think 400 ohms would do the trick. I did this to the iat and coolant temp sensors a few years ago while playing with a Geo Metro. I could start the car like normal and within 1 mile from cold start I could flip the switch and the car would tolerate warm fuel trims. Put it on a spdt switch so you could make it lock up when you wanted. You will loose the overtemp ability if you lock the temp with a resistor. Verify that this chart is accurate for your car, as always use at your own risk.http://i863.photobucket.com/albums/a...o/IMG_0059.jpg

What over temp ability do you mean? I have the 5r55W I believe it is. According to torque od kicks in at 110° normal startup it's around 40-50° this time of year. Wouldn't resistor only need to swing the reading up that 60° and operate normally? Not sure how all this works I need dummy terms and things broke down Barney style. Very capable of turning a wrench but like understanding exactly what I'm doing when doing things. Wires are a nemesis of mine lol

If the diagram in post 3 is correct and the resistance chart for my 4t40 is right what I would do is add a single pole dual throw switch. This is a switch with three posts on the back. The center post goes to the computer, one of the outside posts goes to the factory temp sensor inside the transmission. The other outside post goes through your resistor to ground. The switch has two positions so it is either one way or the other. So if overdrive works over 110 degrees then a resistor with a value of 400 ohms would make the computer think the oil was 175 degrees or so.
Your car is pretty smart though and it may not like seeing the trans oil temp at 175 when the cold soak tells it everything else is 60 degrees. I would drive it a mile or so before flipping the switch, this might avoid a check engine light.
The computer is also looking for overtemp conditions also, you will be taking that away with the resistor.

That sounds feasible. I will look into that. Will I be able to pick the resistor up locally at an auto parts store or would I have to order it online. Wiring shouldn't be too much trouble but sure I'll need some help. Nothing is ever easy for me with wires. I mean a fan with a light and two switches was enough trouble lol didn't get tagged though

I got my resistors at radio shack, they add up when in series. I had to use three in a row to get my car to do what I wanted. I was playing with fuel trim and this was several years ago.

Any chance you have some pics so I can wrap my head around what I need to do. I understand how to hook a switch up but playing with existing wires always throws me off. Am I cutting into a wire or running new wires and just unhooking old and leaving suspended so I could switch it back if I needed to? Sorry I'm such a newbie at this.

I looked through all my Photobucket pictures and I no longer have those pictures so here goes. You are going to cut and extend one existing wire. You are going to attach both halves of that wire to the switch. The switch has three posts and works like a three way house light switch. That type of switch is usually used in your house on stairway lights one at the top and one at the bottom. You are going to connect the part of the wire from the computer to the center or common post. Connect the part of the wire from transmission temp sensor to one of the outside posts. If you did not hook up a wire to the other post the switch would just make or break the circuit.
Solder the resistors end to end to get to the resistance value you want, I would want some value that works and the computer will believe. Add wire to both ends of the resister string long enough to work with, cover securely with tape. Connect one end to chassis ground preferably where another ground attaches. Connect the other end to the switch. Now when you flip the switch the computer either sees the actual temp in the transmission or the fixed value of the resistor string.
I would start each day with the switch in the factory configuration until you need overdrive. Then flip the switch, if you drive far enough to warm up the car flip it back. Repeat....
I hope this helps.

Cut the transmission temperature sensor wire , inside the cab .solder extension, could use bonded pair speker wire.
Insted of running to pin 3 to ground with resistors. Add the resistor/s from the transmission feedpin 1 to the fake signal 3rd turminal. Use a resistor sized to make the fake signal +20to60° this way you also have a functional over temperature, it just kicks in 20-60° earlier if you forget to turn it off.
Would look like this
http://ecomodder.com/forum/attachmen...1&d=1494268671

Nothing quite like wasting fuel to improve exhaust emissions?

I like the switxhable series resistor idea.

Now that makes sense to me and it wouldn't be hard to remove.

Always solder when dealing with the computer... It helps keep the electric Gremlins at bay.

Not my cup of tea but I'll figure it out.have to find the resistors first and a pick up a solder gun. I'll use that for some other things as well at least. Kid have a lot of toys lol

That diagram is a better idea!

You mean Gumby's sweet drawing? I like that too lol that's what I needed to figure it out though sadly

Probably another dumb question but what kind of resistor (s) am I looking for. Feel silly looking for them but started looking yesterday... Really not sure what I'm supposed to pick up. Hook me up with a link if u have one ready. Haven't slept much lately so mind is kinda frazzled. Pictures help lol

Search ebay for this: 1/2 Watt Carbon Film Resistors, 390 ohm, 5 pieces.
The temperature coefficient varys greatly on the temp sensor so I would still add a fixed value. The sensor is also negative coefficient so you have to remove ohms not add to raise temperature. Use the drawing but add the resistor and ground the end to the switch.

Found the parts just need time to pick them up and need to dog around to figure how much wire I need. With Gumby's method when the switch is off it would act like normal or would differential just stay unlocked. Just not sure due to the fact my wife may have to drive it time to time. In my head this way seems it would be normal op with the switch off. Anyways one other quick question. How much slip would be worrisome when not in lockup. Torque was reading as high as 1700 rpm on acceleration.

1700 is a normal stall speed for a car with a small engine.
I would use this drawing since the temperature coefficient is reverse for the tranny temp sensor. You need to remove resistance not add a fixed amount to the existing value.
http://i863.photobucket.com/albums/a...o/IMG_0066.jpg

^^
Good ketch on the decrease....

So I don't need resistors now? Or I need them for the ground? Also need an answer to the wife driving it question lol

I would try a 400 ohm resistor to ground like my drawing. I would only use the switch to get lockup to work while the car is cold. As soon as the car warms up I would flip it back to normal. I would leave the switch in the normal position when another driver uses the car.

Perfect that's exactly what I'm looking for. I can keep it incognito​. Also an anti theft device if u switch it when u park lol