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Automatic Transmission - 6T70/6T75 - Specifications: Other GMC Acadia I

Automatic Trans ~136 words

Shift Solenoid Valve State and Gear Ratio

GearShift SOL 1Shift SOL 21-2-3-4 CL PC SOL 5 N.L.2-6 CL PC SOL 4 N.L.3-5 REV CL PC SOL 2 N.H.LOW REV 4-5-6 CL PC SOL 3 N.H.Gear Ratio
ParkONONOFFOFFOFFON
ReverseONOFFOFFOFFONON2.88
NeutralONONOFFOFFOFFON
1st BrakingONONONOFFOFFON4.484
1stOFFONONOFFOFFOFF4.484
2ndOFFONONONOFFOFF2.872
3rdOFFONONOFFONOFF1.842
4thOFFONONOFFOFFON1.414
5thOFFONOFFOFFONON1.000
6thOFFONOFFONOFFON0.742
Effective Final Drive Ratio - 6T70/75 - 2.77/3.16 For shift solenoids 1 and 2, "ON" = Solenoid Energized (Pressurized) "OFF" = Solenoid De-energized (No Pressure). For pressure control solenoids, "ON" = Pressurized, "OFF" = No Pressure

Shift Speed

Shift @ TPKm/hOSS (RPM)
1-2 @ 12.513283
2-3 @ 12.526566
3-4 @ 12.540870
4-5 @ 12.551.51120
5-6 @ 12.568.51490
6-5 @ 12.5671457
5-4 @ 12.5501088
4-3 @ 12.535761
3-2 @ 12.523500
2-1 @ 12.511239
1-2 @ 2526566
2-3 @ 25481044
3-4 @ 25621349
4-5 @ 25901958
5-6 @ 251002175
6-5 @ 25851849
5-4 @ 25611327
4-3 @ 2541892
3-2 @ 2523500
2-1 @ 2511239

Note. Shift speed points are affected by many different vehicle and transmission operating conditions. The table above represents shift speed points calibrated at specific throttle angles during normal operating conditions and a temperature range between 0-130°C (32-266°F). These shift speed points are also based on an effective final drive ratio of 3.16, and assume a production-intent tire size. The table below illustrates a number of different variables that influence these shift speed points. Based on a given operating condition, these variables may override the normal shift speed points. To assist in monitoring the different variables, the respective scan tool data parameter is also listed.

Scan Tool ParameterShift Speed Variables
Calc. Throttle PositionCalc. Throttle Position (TP) is one of the most important inputs in the transmission shift pattern logic. A very low TP angle will impact the shift pattern by causing upshifts. A very high TP angle will impact the shift pattern by causing downshifts.
Commanded GearBased on numerous inputs, the transmission control module (TCM) selects the optimum gear. Once the TCM commands a gear, the pressure control solenoids are activated to hydraulically control engagement of the proper clutch.
CruiseWhen cruise control is activated, the shift pattern is altered to reduce excessive shifting.
ECTShift speed points may be offset to enhance engine coolant temperature (ECT) warm-up. Also, operating the vehicle at higher engine speeds will reduce the time to warm the ECT and the TFT.
Engine SpeedTo protect against an over speed condition, engine speed is monitored. If the engine speed becomes too high, an upshift will occur.
Engine TorqueEngine torque is used to predict vehicle operating conditions, in order to determine the optimum gear and provide for a smoother ride.
IMSThe internal mode switch (IMS) indicates the position of the transmission manual valve. The operator controls this valve by moving the gear range selector. Therefore, the possible gears may be limited by this valve position.
TCC PC Sol. Duty CycleThe torque converter clutch (TCC) pressure control (PC) solenoid duty cycle indicates when the TCC has been engaged.
TCC Slip SpeedThe TCC Slip Speed indicates the difference between engine speed and transmission input speed. The TCC is locked when slip speed is at or near zero, and may be controlling slip when at lower slip speeds.
TFP Switch 1, 3, 4 or 5The transmission fluid pressure (TFP) switch is used to indicate if fluid pressure to a specific clutch has been applied or released.
Trans. Fluid Temp.A lower TFT will extend shift speeds, a higher TFT, or hot mode condition, will invoke shorter shift speeds in order to establish a shift pattern required to cool the TFT.
Transmission Hot ModeIf the TFT becomes too hot, a hot mode shift pattern is used. The hot mode shift pattern will invoke lower shift speed points to establish a shift pattern necessary to cool the TFT.
Transmission OSSThe transmission output speed sensor (OSS) is one of the most important inputs into the transmission shift pattern logic. A very low transmission output speed will impact the shift pattern by causing downshifts. A very high transmission output speed will impact the shift pattern by causing upshifts.

Shift Speed Variables

Transmission Internal Mode Switch Logic

Gear Selector PositionSignal ASignal BSignal CSignal P
ParkLOWHIHILOW
Park/ReverseLOWLOWHILOW
ReverseLOWLOWHIHI
Reverse/NeutralHILOWHIHI
NeutralHILOWHILOW
Neutral/Drive 6HILOWLOWLOW
Drive 6HILOWLOWHI
Drive 6/Drive 4LOWLOWLOWHI
Drive 4LOWLOWLOWLOW
Drive 4/Drive 3LOWHILOWLOW
Drive 3LOWHILOWHI
Drive 3/Drive 2HIHILOWHI
Drive 2HIHILOWLOW
OpenHIHIHIHI
InvalidHIHIHILOW
InvalidLOWHIHIHI
HI = Ignition voltage LOW = 0 volts

Solenoid Valve Pressure

Requested Pressure (kPa)Actual Pressure
MetricEnglish
None345-900 kPa50-130 psi
200690-900 kPa100-130 psi
4001100-1310 kPa160-190 psi
6001520-1725 kPa220-250 psi
8001860-2070 kPa270-300 psi
10001860-2070 kPa270-300 psi
12001860-2070 kPa270-300 psi
14001860-2070 kPa270-300 psi
16001860-2070 kPa270-300 psi
18001860-2070 kPa270-300 psi
20001860-2070 kPa270-300 psi

Line PC Solenoid Valve Pressure