Wire harness on 700R4??

[Hair]

What exactly does the wire harness that plugs into your overdrive transmission do?

I have a 700R4 and a couple of years back it was shifting up and down and jumping out of gear and acting all crazy. While tinkering with it, I unplugged the wire harness and took off down the road to see what changed. I expected it to not shift at all. But to my surprise I noticed that it shifted out just fine after that. So I left it unhooked and have been driving it that way.

As far as I can tell it has ran fine ever since. No gas mileage loss, no problems whatsoever. It still goes into overdrive...or al least it feels like it does. I hardly ever drive over 60mph. Unless I'm on the interstate and the wife hollers at me :-)

So, what exactly do those wires do?

[robin58]

Should be for torque convertor lockup I think if you're referring to the one I think you are. If not it is the vehicle speed sensor. Take your pick.

[piecesparts]

The plug on the side above the tranny is the power to the lockup converter. If it is a late enough model, then there is a plug at the back on the tailshft for the speed sensor.

The tranny will shift normally, but the .05% gain in the converter locking up will tend to take some milage gain away. If you have the converter working, then you would change your RPMs by about a 200 RPM drop as you driving the same speed on the highway.

[rss396]

The harness affects torque converter
lock up. You will see a light gain in fuel mileage if it is working properly. Several things affect lock up. Throttle position (vacuum switch) early model, TPS later models etc. You did not state the year and engine in your truck. Is the transmission failing now? No lock up creates heat in the convertor.

[Strodder]

So is there a way to activate the lock up converter manually without a computer?

[piecesparts]

There are companies out there that do that or you can do it yourself. Street and Performance used to have a schematic for wiring your harness yourself, but I haven't found it yet on their website.


http://www.bowtieoverdrives.com/cata...AT&CATID=UA1A1

[Strodder]

On my 82 Vette, I had a switch that I would turn off when on the freeway going up hill. It used to bog unless I floored it. That 82 Vette was a DOG.

[robin58]

There's a bunch of diagrams here:

http://www.rowand.net/Shop/Tech/LockupTCCWiring.htm

[EyeH8the24]

have mime locked with the brake light switch ....locks in overdrive till i press brake pedal.but somtimes wish i could unlock it when driving around town and at slower speeds

[arkie726]

I'm not sure on your particular trany, but they used to just run a power and ground in through the plug, when you hit the brake you loose the power, cruise switch I think, anyway I used to put a switch on the dash and run the converter wire to it so when in the city I could shut off the converter, ya know how they shift in and out at about 40mph, it worked great! A couple of bucks for a switch and 30 minutes good to go!