Manual Fourth - Fourth Gear - Drive Range may be selected at any time while the vehicle is being operated in a forward gear range. However, TCM control prevents the transmission from shifting into Fifth gear. When the gear selector lever is moved to Drive Range (4) from Overdrive Range (D), the manual valve also moves. Changes to the hydraulic and electrical systems are as follows:

Overdrive Clutch Releases

Manual Valve: The manual valve moves only to activate the transmission manual shift shaft switch assembly. The transmission manual shift shaft switch assembly signals the TCM that the transmission is in Manual Fourth Range. There is no hydraulic difference between Overdrive Range and Manual Fourth Range at the manual valve.

4-5 Shift Solenoid (SS) Valve: The 4-5 SS valve is energized, allowing feed limit fluid to enter the 4-5 signal fluid circuit. 4-5 signal fluid overcomes 4-5 shift valve spring (373) force and moves the 4-5 shift control valve (375) and the 4-5 shift valve (374) to the applied position.

4-5 Shift Valve: 4-5 fluid is blocked at the 4-5 shift valve (374) allowing overdrive clutch feed 2 fluid to exhaust.

Overdrive Clutch Assembly: Overdrive clutch fluid exhausts from the overdrive clutch piston, allowing the overdrive clutch plates to disengage.

#12 Ball Check Valve: Overdrive clutch fluid seats the #12 ball check valve against the overdrive clutch feed 1 passage and enters the overdrive clutch feed 2 fluid circuit where it exhausts at the 4-5 shift valve.

Shift Accumulation

Overdrive Clutch Accumulator: Overdrive clutch fluid also exhausts from the overdrive clutch accumulator assembly. Accumulator fluid moves the overdrive clutch accumulator piston against accumulator spring force in preparation for another application of the overdrive clutch.

Coast Clutch Applies

4-5 Shift Valve: Coast clutch feed fluid passes through the 4-5 shift valve (374) and into the coast clutch circuit.

Coast Clutch: Coast clutch fluid is routed to the coast clutch piston to apply the coast clutch plates.

In Manual Fourth - Fourth Gear, the TCC will not release if Manual Fourth was selected while the vehicle was operating in Overdrive Range - Fifth Gear with the TCC applied. Under normal operating conditions, the converter clutch operates the same way in Manual Fourth - Fourth Gear as in Overdrive Range - Fourth Gear.

Manual Fourth