How To Control TCC Lock Up
 

I own a 1991 F-250 with the fuel efficent 460. I am getting the truck repainted at maaco $4000. I will be linexing the bed and hand brushing the frame. I love the truck except for the early torque convertor lockup in second gear. Is there any way I can manually control the TCC lockup with a switch?

Yes you can, I have a box that will even change gears.
I take it you have an E4OD so you would cut the circuit #480, a Pink wire with a Yellow stripe.
Tape back the end going to the PCM.
Take the end going to the Transmission and run it to a switch and the other terminal of the switch needs to go to a good ground.

With switch off the clutch is off and when the switch is on the clutch is on.

The above decryption was for a 1992, yours should be the same.

He could also put the switch inline to produce:
OFF- Clutch is off
ON- Clutch operates normally

or use a 3 position switch and have on off and auto.

That is the way I have it in my box.

Were do I find this Pink wire with a yellow tracer at? I will probably just have a switch inline to make it easy. Is there any concern in leaving the torque convertor Disengaged, are there any guidelines? I think I will install a Temp gauge in the outlet cooler line to get the hotest fluid temp out of the TQ.

I am not sure on a 1991 but if it is like a 1992 the posted diagram below will show you. C103 should be on the driver's fender.
No, the clutch is to give you more MPG, with out it, it will act like a TQ without a clutch.

https://i54.photobucket.com/albums/g...DSolenoids.gif

That sounds like nice performance trick. I guess I need to buy a manual to find these wires. Can you do all the wiring under the hood ? I have a 93, will it be the same ?

I do not know what you mean by performance trick, this will cost you MPG and give you no more power. Yes you can and no place else. Yes it will if you have a E4OD.

It main use is to turn off the clutch while troubleshooting shudder in the Transmission.

Cool Thanks for the reply. I wonder were the Transmission tempature sensor is located at, and if it would be possible to tap into it for a temp gauge?

If you use a hi-impedance 0-5 Volt DC meter I would think you could tap into it, if you do let us know how it works out.

Transmission Fluid Temperature (TFT) Sensor 7H141:

The transmission fluid temperature (TFT) sensor is located on the main control valve body (7A100) in the transmission sump. It is a temperature sensitive device called a thermistor. It sends a voltage signal to the powertrain control module. The voltage signal varies with transmission fluid temperature. The powertrain control module uses this voltage signal to determine whether a cold start shift schedule is necessary. The shift schedule is compensated when the transmission fluid temperature is cold. The powertrain control module also inhibits torque converter clutch operation at low transmission fluid temperatures and corrects EPC pressures for temperature.

The Transmission Fluid Temperature (TFT) sensor is a thermistor that changes resistance in response to temperature. The TFT sensor resistance decreases as the surrounding fluid temperature increases. The resistance variation is converted into a voltage signal and sent to the PCM to give an indication of the transmission fluid temperature.

Note: Voltage values are calculated for VREF = 5.0 volts: These values may vary 15 percent due to sensor and VREF variations. Transmission fluid temperature must be minimum of 10°C (50°F) before taking transmission fluid temperature sensor resistance measurements.

https://i54.photobucket.com/albums/g.../TFTSensor.gif

https://i54.photobucket.com/albums/g...ission/TFT.gif


Good Luck

Will having the c103 coming from trans grounded for a long time hurt it ?

C103 is a connector, how are you going to ground it?
If you mean circuit #480 the engine will die when you come to a stop. It would be like trying to drive a standard (stick) shift without ever pushing in on the clutch.

Sorry, I was confused. I thought I was reading it would keep the Tourqe Converter from locking up. Thats what I would want it to do till atleast 55 mph intead of 35 mph.

You would need to open (break) the wire or put it on a switch that would open (break) it then. That way the computer could not ground it to make the clutch come on.