Overdrive in automatic in cold weather?

[me and my metro]

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.

[ecocruze]

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

[me and my metro]

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.

[ecocruze]

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.

[me and my metro]

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.

[gumby79]

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

[oil pan 4]

Nothing quite like wasting fuel to improve exhaust emissions?

I like the switxhable series resistor idea.

[ecocruze]

Originally Posted by gumby79

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

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

[gumby79]

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

[ecocruze]

Originally Posted by gumby79

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