I was wondering where its getting the signal to shift and lock up tc? Is it from the tone ring or camshaft or both? Something else?

 

I know Torque management is involved so I would say the computer which is reading several parameters. Fuel, RPM, Air intake, Boost would all have to be involved wouldn't it?

 

Throttle pressure.

 

I don't think it's completely mechanical. I think it's getting a quick primitive signal from the ECU. I think this because the engine defuels momentarily to allow a shift or TC lockup. In my case, I have a Goerend triple disc and my engine defuel doesn't time well with the shift because it takes longer for the triple disc to lock. At WOT this results in a thump because engine power is being applied at the time when the disc locks. Of course, it's not supposed to do that. It does and I manage it.

 

Ok, its not completely mechanical. It takes throttle pressure and road speed. How hard it applies depends on valves and hole diameters in the valve body. The computer commands lock up, the valve body completes the task.

 

The three biggest inputs are engine RPM, throttle position, and governor pressure (road speed). At a given RPM, higher throttle position creates higher throttle pressure and acts to make the shifts later and firmer. At the same time, the higher the road speed, the higher the governor pressure, which acts to make the shifts come sooner.

Traditionally, these functions were all completed mechanically. Governor pressure was created by a valve mounted on the output shaft that had a weight attached that would use centrifugal force to increase governor pressure in a linear manner as the road speed increased, approx 1 PSI per MPH I believe.

Throttle pressure on a Dodge was controlled by a valve attached directly to the throttle cable by a cable. Other brands used a modulator valve which used engine vacuum to modulate throttle pressure.

Essentially, throttle pressure and governor pressure would be applied to opposite sides of the appropriate valves in the valve body. They would create a delicate balancing act that would produce shifts at the proper time and speed with regard to your driving manner. If you took off with the pedal floored, your shifts would be late and firm, allowing your engine to reach high speeds before each upshift. If you started out from a stop with a very light foot, your upshifts would be very early and soft.

The automatic transmission and valve body are really an amazing piece of engineering. They have been evolving greatly in this age of electronic controls, as solenoids can control and modulate fluid direction and pressures with less and less need for a valve body. Of course, road speed and throttle pressure are now simply electronic signals that are already available for use by the transmission's processor. So while automatic transmissions are becoming more complicated every year, they are also becoming more simple.

 

That helps quite a bit. Where are the sensors that provide this information to the ecm? Im guessing one is the tone ring. Does it provide throttle position?

I know that there is a sensor on the cam but I'm not sure if this is providing any information for the tranny.

 

Typically, the engine's crankshaft position sensor (the sensor that reads the tone ring on the harmonic balancer) provides the RPM signal; throttle position sensor (or APPS) provides the throttle position information. Road speed data is provided by the transmission's own output speed sensor and governor pressure is then created by the governor pressure solenoid and monitored by the governor pressure transducer.