At 05:45 PM 5/22/05, you wrote:
>SNIP> I don't know about the newer trannies (46re and 44re) <SNIP>
> -Jon-
The 44RE is electronically controlled using a governor pressure solenoid
to vary the governor pressure. The shifts are controlled by the valve body
by conventional shift valves for 1-2 and 2-3 upshifts. The 3-4 upshift and
4-3 downshifts are controlled by a solenoid. Although the shifts are controlled
by shift valves for the lower gears, the higher gear is electronically
controlled
because the governor pressure acting against it is controlled by the PCM.
The throttle pressure is controlled by a standard cable and throttle valve.
The PCM inputs for this system include engine rpm, throttle position sensor,
vehicle speed sensor, transmission output speed sensor, governor pressure
sensor,
transmission fluid temperature sensor and overdrive "off" switch.
The PCM outputs are the 3-4 shift solenoid, the governor pressure solenoid
and the torque converter clutch solenoid.
Here's how this system operates: As the output shaft begins to move,
a 2-wire AC generator (transmission output speed sensor) begins to signal
the PCM of the rpm. As the shaft speed increases, the PCM controls
the governor pressure solenoid accordingly by a pulse-width modulated signal.
Feedback to the PCM is provided by a governor pressure sensor to verify
that the pressure actually changes. The pressure sensor is a 5-volt
reference sensor.
When the wheels are not rotating, voltage around 0.6 V is normal. As the
wheels begin
to speed up, the voltage should increase proportionately. If the voltage
does increase,
then the pressure is increasing as it should - this should be verified with
a pressure gauge.
This variance of pressure acts upon the shift valves in the valve body
along with
the throttle pressure to provide the shifts. As speed warrants, the PCM
will apply
the 3-4 overdrive solenoid, which is the only shift solenoid used on this
system.
The OD inputs are overdrive off switch, TPS, VSS, transmission temp sensor,
output speed sensor and engine rpm. The torque converter clutch (TCC) solenoid
will normally operate in overdrive, but the PCM can operate the TCC in
third gear
if the overdrive off switch is selected. Inputs for TCC include OD off switch,
TPS, engine rpm, VSS, output speed and transmission temperature sensor.
The transmission temperature sensor is mounted on the overdrive/torque
converter clutch solenoid assembly and provides input to the PCM. When
the temperature sensor reports 30 degrees F or colder, there will be no
overdrive,
and below 50 degrees F, there will be no torque converter clutch. If the
transmission
fluid temperature sensor reports an overheating condition (over 260 degrees F)
and the transmission is currently in overdrive, the PCM will downshift to
third gear.
The PCM will also light the LED in the dash-mounted OD off switch until the
temperature
drops below 230 degrees F. However, the torque converter clutch may still
be operational.
I'm guessing that the above would also apply to the 46RE.
Hope this adds confusion to the discussion :-)
Bob
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