Can someone explain the lock-up converter process on a 92 700R4. Mine will only lock-up when the motor reaches 220 degrees. I recently changed the trans cooler line routing to run through an external filter then cooler in front of the condensor and back to the trans. I don't let it run through the radiator anymore since every 10 degree drop in temp adds 10.000 miles to the life of a trans.

 

Really, 220?
It might be your computer, in which case you need a chip or maybe an inline resistor to trick the chip.
But if it's mechanical, then there's a thermal vacuum switch. It'll be threaded into the top of the thermostat housing, or right beside it, in the intake manifold. If so, then bypassing the TVS is easy and cheap.

 

Well I would like a chip to get rid of Vats and some other stuff but tell me how to bypass it and have it work like it is supposed to.

 

First you have to determine if yours is TVS-controlled or computer-controlled.

 

How do I do that? It has the cable going to the passenger side of the trans that goes up to the throttle body bracket. It also has the electronic plug in the drivers side. The car is a dead stock 1992 Z28 convertible 305 TPI automatic. I have changed some things but the motor and trans are dead stock at this time. I would like to have control over the lock-up with a rocker switch so I need to know what switch to bypass or what wires to splice into to run to a switch near the dash. When it gets warm (really warm) it will lock-up in what feels like second gear on. Untill it gets warm it will not lock up at all. It takes around 12 to 15 miles for it to start working. Once it starts working it works great.

 

Good news: it's working exactly as it is supposed to. Are you really sure you want to mess with a good thing? And if so, why? Did you swap in a big bad camshaft? Or a taller axle ratio? Or did you used to drive a non-GM automatic?
What you have now is the best automatic short of the latest 6L80E/6L90E. Anything else you may have gotten used to would have screwed you up.

 

The torque converter is electrically controlled - there were no vacuum controlled parts with a 700R4.

The ECM lockls/unlocks the converter, at speeds as low as 35mph, and in either 3rd or 4th gear.

To manually lock/unlock the converter, you must change the solenoids inside the tranny, which requires dropping the pan and losing all your fluid. You need a TC lockup kit from like TCI or others. About $100.

But, it sounds like your TC is locking as it should. Sometimes. folks have issues with it locking on hills and such, and sometimes it locks/unlocks sporacially under load or on hills - you just shift into D rather than OD when this irritation occurs.

 

If you must do it, you need to wire in a brake switch, so that the converter will unlock whenever you touch the brake pedal. Also wire in a vacuum switch, so that the converter will only lock when you are over 12" or so of manifold vacuum.

 

Thanks guys but you don't understand. The car is all stock except for the 9 bolt rear I installed. I bought it because it had posi, PBR rear disc and an aluminum driveshaft with it. The engine and trans are stock 92 Z28 convertible 305 TPI and 700r4. When it gets to 220 the trans locks up perfectly in third and fourth gear. I did add a bigger Be Cool radiator and routed the trans cooling lines to go through an external filter and front mounted cooler mounted on the condensor. It does not go through the radiator anymore making the trans fluid much cooler. It just takes about 6-10 miles for it to warm up and start locking up. It should lock up regardless of the temp or so I thought.

 

It should start to lock up under ECM control once the CTS is above 122* F. The ECM provides a ground for the TCC solenoid. Power is provided via a fuse, through the brake pedal switch, then on to the transmission TCC solenoid.

If the 220* engine temperature is correct (is the gauge correct?), the transmission may be getting hot enough for the thermal switch to close. I'm not sure which 700R4's have the thermal switch. I know that some '92 f-body's do have them. They are located in the trans pan.

Did this start to occur after the install of the trans cooler? If so the trans may be getting too hot.

Back to ECM control, pin F of the ALDL connector is the line from the ECM. At key-on, engine-off it should have +12 volts on it (measured to ground). It will get pulled to ground by the ECM when it locks the TCC.

You can ground that pin to force the TCC to lock up.

RBob.

 

Perfect, that is what I was wanting to know. I can simply add a toggle to the F wire on the ALDL and make it come on by grounding it. If it doesn't come on I have to drop the pan and start putting in new switches. I almost forgot. Has anyone added paddle shift to a third gen and if so how did they do it? Do you have to get a 4L60E or 4l80E? Will one of those new 6L90E 6 speed autos fit in our car?