Hydraulic Circuits

Hydraulic Circuits


Hydraulic Circuit Identification and Function






Hydraulic Circuit Identification Chart









Main Control Hydraulic Passage Identification



















Line Pressure Hydraulic Circuits

The Transmission Control Module (TCM) controls line pressure with the Line Pressure Control (LPC) solenoid. Varying pressure from the LPC solenoid effects shift feel while allowing sufficient pressure for clutch application.

When the engine is running, the pump supplies pressure to the main regulator valve through the PUMP circuit. The position of the main regulator valve controls line pressure (in the PUMP circuit). Pressure from the LPC solenoid through the VFS5 circuit controls the position of the main regulator valve.

The main regulator valve varies pressure in the SCHG circuit. The higher the pressure in the SCHG circuit, the lower the line pressure (PUMP circuit) is. As SCHG pressure decreases, line pressure (PUMP circuit) increases.






Lubrication Hydraulic Circuits

The main regulator valve supplies pressure to the lubrication control valve through the CREL F circuit. When the Torque Converter Clutch (TCC) is applied, the lubrication control valve supplies the transmission lubrication through the COOLF circuit to the LUBE circuit.

When the TCC is released, return fluid from the torque converter is supplied to the LUBE circuit through the CAPLY, CAPLY EX and DBACK circuits.

Pressure in the LUBE circuit either circulates through the thermal bypass valve when Transmission Fluid Temperature (TFT) is below operating temperature or through the transmission fluid cooler when the transmission fluid is at or above operating temperature. Return fluid from the thermal bypass valve or the transmission fluid cooler enters the input shaft through the pump assembly and flows through passages in the input shaft, intermediate shaft and output shaft to provide lubrication for the transmission.






Torque Converter Hydraulic Circuits

When the TCC is released, line pressure is supplied to the converter release regulator valve from the lubrication control valve through the CREL F circuit. The converter release regulator valve supplies pressure to the torque converter through the CREL circuit to release the torque converter.

CREL pressure exits the torque converter through the CAPLY circuit and goes to the bypass clutch control regulator valve. The bypass clutch control regulator valve directs the fluid back to the converter release regulator valve through the CAPLY EX circuit. The converter release regulator valve directs the fluid to the DBACK circuit where it supplies lubrication in the LUBE circuit.





When the TCC is applied, the TCC solenoid applies hydraulic pressure to the bypass clutch control regulator valve and the converter release regulator valve through the VFS6 circuit to position the valves to apply the TCC.

Line pressure is supplied to the bypass clutch control regulator valve from the main regulator valve. The bypass clutch control regulator valve directs regulated line pressure to the TCC through the CAPLY circuit to apply the TCC.

CAPLY pressure exits the torque converter through the CREL circuit and goes to the converter release regulator valve.

For torque converter description and function, refer to Torque Converter Contamination Inspection Torque Converter Contamination Inspection.






Solenoid Hydraulic Circuits

LINE pressure from the pump is directed to the individual shift, TCC and LPC solenoids by the solenoid regulator valve through the SREG circuit. The solenoids, controlled by the TCM, direct full or regulated SREG pressure to the valves that they control.

For electrical operation of the solenoids, refer to Transmission Electronic Control System Transmission Electronic Control System.

The LPC solenoid sends varying pressure to the main regulator valve to control line pressure.

In the PARK and NEUTRAL position, the TCM supplies low amperage to Shift Solenoid D (SSD) to apply high-regulated pressure to the solenoid multiplex valve which directs the pressure to the D1 and D2 regulator and latch valves to apply the low/reverse clutch (D).





In the REVERSE position, the TCM supplies low amperage to Shift Solenoid B (SSB) to apply high-regulated pressure to the clutch B regulator and latch valves to apply the direct clutch (B). The TCM also supplies low amperage to SSD to apply high-regulated pressure to the solenoid multiplex valve which directs the pressure to the D1 and D2 regulator and latch valves to apply the low/reverse clutch (D).





In 1st gear, the TCM supplies high amperage to Shift Solenoid A (SSA) to apply high-regulated pressure to the clutch A regulator and latch valves to apply the forward clutch (A). The TCM also supplies low amperage to SSD to apply high-regulated pressure to the solenoid multiplex valve which directs the pressure to the D1 and D2 regulator and latch valves to apply the low/reverse clutch (D).





In 2nd gear, the TCM supplies high amperage to SSA to apply high-regulated pressure to the clutch A regulator and latch valves to apply the forward clutch (A). The TCM also supplies high amperage to Shift Solenoid C (SSC) to apply high-regulated pressure to the clutch C regulator valve to apply the intermediate clutch (C).





In 3rd gear, the TCM supplies high amperage to SSA to apply high-regulated pressure to the clutch A regulator and latch valves to apply the forward clutch (A). The TCM also supplies low amperage to Shift Solenoid B (SSB) to apply high-regulated pressure to the clutch B regulator and latch valves to apply the direct clutch (B).





In 4th gear, the TCM supplies high amperage to SSA to apply high-regulated pressure to the clutch A regulator and latch valves to apply the forward clutch (A). The TCM also supplies low amperage to SSD to apply high-regulated pressure to the solenoid multiplex valve which directs the pressure to the clutch E regulator and latch valves to apply the Overdrive (O/D) clutch (E). The TCM turns on Shift Solenoid E (SSE) to apply pressure to the solenoid multiplex valve and the drive enable valve to direct SSD pressure to the clutch E regulator and latch valves.





In 5th gear, the TCM supplies low amperage to SSD to apply high-regulated pressure to the solenoid multiplex valve which directs the pressure to the clutch E regulator and latch valves to apply the O/D clutch (E). The TCM turns on SSE to apply pressure to the solenoid multiplex valve and the drive enable valve to direct SSD pressure to the clutch E regulator and latch valves. The TCM also supplies low amperage to SSB to apply high-regulated pressure to the clutch B regulator and latch valves to apply the direct clutch (B).





In 6th gear, the TCM supplies low amperage to SSD to apply high-regulated pressure to the solenoid multiplex valve which directs the pressure to the clutch E regulator and latch valves to apply the O/D clutch (E). The TCM turns on SSE to apply pressure to the solenoid multiplex valve and the drive enable valve to direct SSD pressure to the clutch E regulator and latch valves. The TCM also supplies high amperage to SSC to apply high-regulated pressure to the clutch C regulator valve to apply the intermediate clutch (C). To apply the TCC, the TCM supplies high amperage to the TCC solenoid to apply high-regulated pressure to the converter release regulator valve and the bypass clutch control regulator valve to apply the TCC.





In 3rd gear fail safe, all solenoids are off. SSB, in the off position, applies high pressure to the clutch B regulator and latch valves to apply the direct clutch (B). The forward clutch (A) is hydraulically applied in 3rd gear fail safe. The LPC solenoid provides maximum solenoid pressure to the main regulator valve for maximum line pressure. Also, SSD is on which applies high pressure to the solenoid multiplex valve which is directed to the drive enable valve where it is blocked.






Forward Clutch (A) Hydraulic Circuits

To apply the forward clutch (A), the manual valve must be in the DRIVE, 3, 2 or 1 position to provide line pressure to the clutch A regulator valve through the DRIVE circuit.

For the forward clutch (A) to apply, SSA provides regulated solenoid pressure from the SREG circuit to the clutch A regulator and latch valves through the VFS1 circuit to position the valves to apply the forward clutch (A). As the forward clutch is applied, SSA increases pressure to the clutch A regulator and latch valves.

The clutch A regulator valve provides regulated line pressure to the CL A circuit to apply the forward clutch (A).





The forward clutch (A) is released when the manual valve is in the NEUTRAL, REVERSE or PARK position or the when the manual valve is in the DRIVE position with the transmission in 5th or 6th gear.

SSA lowers pressure to the clutch A regulator and latch valve to position the valves to lower the regulated line pressure in the CL A circuit to release the clutch.

When the forward clutch (A) is released, the clutch A regulator valve directs exhaust circuit pressure from the CL EXH circuit to the CL A circuit to fill the circuit and the forward clutch (A) with fluid at low pressure, approximately 21 kPa (3 psi).






Direct Clutch (B) Hydraulic Circuits

To apply the direct clutch (B), the manual valve can be in the REVERSE, DRIVE, 3, 2 or 1 position to provide line pressure to the clutch B regulator valve through the REV/DRIVE circuit.

For the direct clutch (B) to apply in reverse, SSB provides regulated solenoid pressure from the SREG circuit to the clutch B regulator and latch valves through the VFS2 circuit to position the valves to apply the direct clutch (B). As the direct clutch is applied, SSB increases pressure to the clutch B regulator and latch valves.

The clutch B regulator valve provides regulated line pressure to the CL B circuit to apply the direct clutch (B).





When the direct clutch (B) is applied in 3rd and 5th gear, regulated solenoid pressure from the D1 latch valve is supplied to the clutch B regulator valve through the VFS2D circuit and opposes pressure from the VFS2 circuit for clutch B valve positioning.





The direct clutch (B) is released when the manual valve is in the PARK or NEUTRAL position or when the manual valve is in the DRIVE position with the transmission in 1st, 2nd, 4th or 6th gear.

In NEUTRAL or PARK, the manual valve does not supply line pressure to the clutch B regulator valve. SSB lowers pressure to the clutch B regulator and latch valve to position the valves to lower the regulated line pressure in the CL B circuit to release the clutch.





In 1st, 2nd, 4th or 6th gear, the manual valve supplies line pressure to the clutch B regulator valve. SSB lowers pressure to the clutch B regulator and latch valve to position the valves to lower the regulated line pressure in the CL B circuit to release the clutch.

When the direct clutch (B) is released in 1st, 2nd, 4th or 6th gear, the clutch (B) regulator valve directs exhaust circuit pressure from the CL EXH circuit to the CL B circuit to fill the circuit and the direct clutch (B) with fluid at low pressure, approximately 21 kPa (3 psi).






Intermediate Clutch (C) Hydraulic Circuits

To apply the intermediate clutch (C), the manual valve can be in the DRIVE, 3, 2 or 1 position to provide line pressure to the clutch C regulator valve through the DRIVE circuit.

SSC provides regulated solenoid pressure from the SREG circuit to the clutch C regulator valve through the VFS3 circuit to position the valve to apply the intermediate clutch (C). As the intermediate clutch (C) is applied, SSC increases pressure to the clutch C regulator valve.

The clutch C regulator valve provides regulated line pressure to the CL C circuit to apply the intermediate clutch (C).

Regulated solenoid pressure from the clutch E latch valve is supplied to the clutch C regulator valve through the VFS3E circuit and opposes VFS3 pressure for clutch C regulator valve positioning in 6th gear only.





To release the intermediate clutch (C) when the manual valve is in the DRIVE, 3, 2 or 1 position SSC lowers pressure to the clutch C regulator valve to position the valve to lower the regulated line pressure in the CL C circuit to release the clutch.

When the intermediate clutch (C) is released, the clutch C regulator valve directs exhaust circuit pressure from the CL EXH circuit to the CL C circuit to fill the CL C circuit and the intermediate clutch (C) with fluid at low pressure, approximately 21 kPa (3 psi).

In PARK, REVERSE or NEUTRAL, the manual valve does not supply line pressure to the clutch C regulator valve.






Low/Reverse Clutch (D) Hydraulic Circuits

To apply the low/reverse clutch (D), the manual valve can be in any position. Line pressure is supplied to the D1 and D2 regulator and latch valves by the pump through the PUMP circuit.

SSD provides regulated solenoid pressure from the SREG circuit to the solenoid multiplex valve through the VFS4 circuit where it is directed to the D1 and D2 regulator and latch valves through the CL DC circuit to position the valves to apply the low/reverse clutch (D). As the low/reverse clutch (D) is applied, SSD increases pressure to the D1 and D2 clutch regulator and latch valves.

The clutch D1 and D2 regulator valves provide regulated line pressure from the PUMP circuit to the CL D1 and CL D2 circuits to apply the low/reverse clutch (D).





To release the low/reverse clutch (D), the manual valve can be in the DRIVE, 3 or 2 position. SSD lowers pressure to the VFS4 circuit which lowers pressure in the CL DC circuit to position the D1 and D2 regulator and latch valves to lower pressure in the CL D1 and CL D2 circuits and release the low/reverse clutch (D).

When the low/reverse clutch (D) is released, the clutch D2 latch valve directs line pressure regulated to approximately 21 kPa (3 psi) to the CL EXH circuit which fills the volume of the unused clutches and circuits.

When the low/reverse clutch (D) is released, the CL EXH circuit supplies the D1 regulator valve which fills the CL D1 circuit and the low/reverse (D) clutch.






Overdrive (O/D) Clutch (E) Hydraulic Circuits

To apply the O/D clutch (E), the manual valve must be in the DRIVE position. Line pressure is supplied to the clutch E regulator valve.

SSD provides regulated solenoid pressure from the SREG circuit to the solenoid multiplex valve through the VFS4 circuit. SSE supplies pressure to the solenoid multiplex valve and the drive enable valve to position the valves to direct pressure from the VFS4 circuit to the CLEC F and CLEC circuits to position the clutch E regulator and latch valves to apply the O/D clutch (E). As the O/D clutch (E) is applied, SSD increases pressure to the clutch E regulator and latch valve.

The clutch E regulator valve provides regulated line pressure from the DRIVE circuit to the CLE circuit to apply the O/D clutch (E).





To release the O/D clutch (E), the manual valve can be in any position. SSD lowers pressure to the VFS4 circuit which lowers pressure in the CLEC and CLEC F circuits and releases the O/D clutch (E). SSE blocks SREG pressure to the solenoid multiplex valve and the drive enable valve to allow SSD to control low/reverse clutch (D) operation.

When the O/D clutch (E) is released, the clutch E regulator valve directs exhaust circuit pressure from the CL EXH circuit to the CL E circuit to fill the circuit and the clutch with fluid at low pressure, approximately 21 kPa (3 psi).