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Hi, I read up on how to adjust the TCC Parameters but have one last parameter that is still a mystery to me, TCC Min and Max Pressures. I have already adjusted the PWM min to 90% and max to 100% and Now have a solid engagement of the TC. My stock TCC Pressure min is set to 0 and max is set to 120. How do the TCC Pressure min and max corrolate with the Pulse Width Modulation % (PWM)?
Thanks in advance!
Jo-eL
TCC pressure is controlled by the PWM duty cycle on the TCC hydaralic circuit...
TCC PWM DC 100% is TCC full pressure, TCC PWM DC 0% is TCC zero pressure, max and min are in between.
So changing the min/max pressures would't do anything?
TCC min/max pressure: These would do something, but leave them alone, they appear to be related to "available" range of pressure.
TCC min/max PWM: these determine the PWM range when the PCM applies the TCC; the PCM may fully apply (lock) the TCC (PWM > 90%), or it may partially apply it (30% < PWM < 90%) for some reason or other.
Typically, you would do this:
- TCC min and max pressures are left at 0 psi and 120 psi,
- TCC max PWM is set to 95%-100%,
- TCC min PWM is set to about 50%-90% below TCC max PWM (see note *).
* If TCC min PWM is set to 90% or higher, then a partial apply becomes a lock.
Why would the PCM ever want to do a Partial lock? Also, I was monitoring my TCC Duty and when the TC is unlocked, Duty is steady at 100% but once the TCC applies, Duty drops to about 98%. Why would the Duty be at 100% when the Torque Converter is unlocked?
Jo-eL
I've seen various GM cars where at light throttle/load the TCC is only "partly" locked (i.e. TCC PWM DC is somewhere between 30% and 50%)...
it takes more energy to lock the TCC, and if the turbine/stator are able to achieve fluid coupling/synchrinization (which easily happens at light throttle/load), then there might be a MPG improvement... GM has some reason for doing it.
4L60E:
when TCC is unlocked, the PCM will park TCC PWM at 90% or more...
I'm not sure of the real reason, but I suspect this is to keep the TCC PWM circuit clean (but I don't know for sure).
( this is why a 4L80E conversion cannot use the TCC PWM signal to directly drive the TCC PWM solenoid...
it must use either the TCC On/Off signa,l or it must use a relay to gate the TCC PWM signal with the TCC On/Off signal ).