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THM 4T65-E UPDATE HANDBOOK

The hydraulic diagram shown in Figure 64 represents the transmission in either; Park, Reverse, Neutral, or
Drive 1st. Gear, including Manual Low. When you look at the feed from second gear to the TCC PWM
solenoid, you will notice the lack of oil pressure in the circuit. This is because oil pressure is present only
when the second clutch is applied, which would be 2nd, 3rd, and 4th gears on this transaxle. With no oil
pressure at the second clutch, the TCC control valve stays at rest in it’s bore away from the spring. This
results in oil pressure being present at the TCC Release Switch in the Pressure Switch Assembly, keeping
the Release Switch open.
The hydraulic diagram shown in Figure 65 represents the transmission in Drive 2nd. Gear, 3rd. Gear, and
4th. Gear. Notice the presence of 2nd gear oil pressure in the circuit. With the solenoid “OFF” and not
energized, the solenoid should exhaust 2nd clutch pressure so that the pressure in the solenoid doesn’t
become great enough to cause the TCC valve to stroke inward against the spring. Lock-up will not be
engaged at this time.
The hydraulic diagram shown in Figure 66 also represents the transmission in Drive 2nd. Gear, 3rd. Gear,
and 4th. Gear, lock-up clutch applied. If for some reason the TCC solenoid is not capable of exhausting 2nd
clutch oil pressure, the result will be the TCC control valve overcoming spring tension and moving into the
lock-up position. Lock-up release oil will exhaust through the valve, the converter clutch will engage with
the shift into second gear. Replacing the TCC PWM solenoid should correct the problem.
It has been found that although identical in appearance, a new factory TCC PWM solenoid for the 4L60E
has been used in the 4T65E in different instances. Even though the solenoids look identical, they "Will
Not" interchange.
CAUTION:
Use "ONLY" the TCC PWM Solenoid for a 4T65-E transaxle, identified by the part number on the
canister for identification, and available under OEM part number 24227747, which supercedes all
previous part numbers. Refer to Figure 58.
DESCRIPTION OF THE 3 FOLLOWING
PARTIAL HYDRAULIC SCHEMATICS
AUTOMATIC TRANSMISSION SERVICE GROUP
Technical Service Information
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Copyright © 2006 ATSG

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