Chevrolet Equinox Service Manual: Drive Range, Third Gear Default Automatic Transmission Unit

If the transmission is in 1st, 2nd or 3rd gear during a transmission electrical componentfailure, the transmission will default to 3rd-gear. All solenoids will default totheir normal state. If the torque converter clutch was applied, it will release. Thisdefault action will enable the vehicle to be safely driven to a service center.

1-2-3-4 Clutch Stays Applied

Shift Solenoid 2

Shift solenoid-2 defaults to it's normally-closed state (OFF), and SOL-2 fluid exhauststhrough the solenoid.

Clutch Select Valve 3

Solenoid-2 fluid pressure no longer holds the clutch select valve-3 open. When thevalve moves back to the closed position, it opens the 1234-clutch default fluid circuit,and 1234-default fluid is routed to the 1-2-3-4-clutch regulator valve.

1-2-3-4 Clutch Regulator Valve

With the absence of PCS-1234 clutch fluid, due to the default state of the 1234-pressurecontrol solenoid-5, the 1-2-3-4-regulator valve would close from spring force. However,the 1234-clutch default fluid enters behind the 1-2-3-4-regulator shuttle valve andkeeps the valve in the open position.

1-2-3-4 Clutch

With the 1-2-3-4-clutch regulator valve still held in the open position, the 1-2-3-4-clutchwill stay applied.

3-5 Reverse Clutch Applied or Applies

35R Pressure Control Solenoid 2

The normal state for the 35R-pressure control solenoid-2 is ON, therefore PSC-35 reverseclutch fluid will still be routed to the 3-5-reverse clutch regulator valve and the3-5-reverse clutch boost valve.

3-5 Reverse Clutch Regulator Valve

PCS-3-5 reverse clutch fluid moves the 3-5-reverse clutch regulator valve against3-5-reverse clutch regulator valve spring force and 3-5-reverse clutch feedback fluid.This allows 3-5-reverse feed to pass through the valve and enter the 3-5-reverse clutchcircuit. 3-5-reverse clutch fluid is then routed to the 3-5-reverse clutch, the 3-5-reverseboost valve and the clutchselect valve-2. When the 3-5-reverse clutch regulator valve is in this position, PS2-fluidfrom the pressure switch-2 exhausts through the valve, allowing the switch to close.

3-5 Reverse Clutch Boost Valve

PCS-3-5 reverse clutch fluid pressure acts on a differential area moving the 3-5-reverseclutch boost valve against the 3-5-reverse clutch boost valve spring. The 3-5-reverseclutch fluid passes through the valve and enters the 3-5-reverse clutch feedback circuit.As PCS-3-5 reverse clutch fluid pressure is increased to a given value, the 3-5-reverseclutch boost valve opens the 3-5-reverseclutch feedback circuit to exhaust. This results in the 3-5-reverse clutch regulatorvalve moving to the full feed position sending full 3-5-reverse clutch feed pressure(full line pressure) to the clutch.

3-5 Reverse Clutch

The 3-5-reverse clutch fluid enters the 3-5-reverse/456 clutch housing to move thepiston against spring force to apply the 3-5-reverse clutch plates.

Drive Range, Third Gear Default

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