Automatic Transmission - 4L60-E/4L65-E - Introduction: Other Hummer H2 I

Low and Reverse Clutch Spacer Plate Selection

Low and Reverse Clutch Plate Selection Table

Forward Clutch Backing Plate Selection

Forward Clutch Backing Plate Selection

Third and Fourth Clutch Backing Plate Selection

3rd and 4th Clutch Backing Plate Selection Table

Reverse Input Clutch Backing Plate Selection

Reverse Input Clutch Backing Plate Selection Table

Oil Pump Rotor and Slide Measurement

Oil Pump Rotor and Slide Measurement

Scheme 230

2-4 Servo Pin Selection

Range Reference

Range Reference Table

Shift Solenoid Valve State and Gear Ratio

Shift Solenoid Valve State and Gear Ratio 4L60-E

Shift Speed

Shift Speed (N Truck 4L60-E)

Transmission Range Switch Logic

Transmission Range Switch Logic

Line Pressure

Line Pressure (4L60-E)

Component Resistance

Component Resistance

Tools Required

J 41364-A Park/Neutral Switch Aligner

J 29714-A Servo Cover Depressor. See Special Tools and Equipment .

1. J 43911 Selector Shaft Seal Remover. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
2. J 43909 Selector Shaft Seal Installer. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .

J 28458 Seal Protector Retainer Installer. See Special Tools and Equipment .

J 8763-02 Holding Fixture and Base

1. Install the J 8763-02 onto the transmission.
2. Install the J 8763-02 into the base.

J 41510 T-50 Plus Bit. See Special Tools and Equipment .

1. Remove the converter housing bolts (94). Use the J 41510 . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
2. Remove the converter housing (102).

J 29714-A Servo Cover Compressor. See Special Tools and Equipment .

1. Install the J 29714-A . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
2. Tighten the J 29714-A bolt to compress the servo cover. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
3. Remove the servo cover retaining ring (29) and the J 29714-A . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
4. Remove the servo cover (28) and O-ring seal (27). If the servo cover seems to be hung up on the seal, cut and remove the O-ring seal before removing the cover.
5. Remove the 2-4 servo assembly.

Scheme 231

Disassemble the 2-4 servo assembly.

J 33037 2-4 Intermediate Band Apply Pin Gauge. See Special Tools and Equipment .

1. Disassemble the 2-4 servo assembly. If necessary, refer to «2-4 Servo Disassemble»(ref-187261-S01680151922005083100000) .
2. Install the band apply pin (13) and the J 33037 (1). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
3. Install the servo cover retaining ring (29) to secure the tool.
4. Apply 11 N.m (98 lb in) torque. If the white line appears in the gauge slot (1), the pin length is correct.
5. If a new pin is needed, refer to «2-4 Servo Pin Selection»(ref-187261-S04543979392005083100000) in order to determine correct pin length.

Transmission End Play Check

Tools Required

1. J 25022 End Play Fixture Adapter (245 mm and 258 mm). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
2. J 34725 End Play Checking Adapter (298 mm). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
3. J 43205 End Play Fixture Adapter (300 mm). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
4. J 24773-A Oil Pump Remover. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
5. J 8001 Dial Indicator Set
6. J 25025-7A Dial Indicator Mounting Post. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .

1. Install an end play fixture adapter. Use J 25022 for a 245 mm and 258 mm turbine shaft (1). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) . Use J 34725 for a 298 mm turbine shaft (2). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) . Use J 43205 for a 300 mm turbine shaft (3). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
2. Install the J 24773-A . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
3. Remove an oil pump bolt.
4. Install J 25025-7A (or a 278 mm or 11 in bolt) and lock nut. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
5. Install J 8001 .
6. Set the J 8001 to zero.
7. Pull up on J 24773-A . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) . Proper end play should be 0.13-0.92 mm (0.005-0.036 in).
8. The selective washer (616), which controls the end play, is located between the input housing (621) and the thrust bearing (615) on the oil pump hub. If the end play measurement is incorrect, refer to «End Play Specifications»(ref-187261-S05710402912005083100000) . Choose a new selective washer (616) based on the original selective washer and the information contained in the table. If the dial indicator shows no end play, the selective washer (616) and thrust bearing (615) may have been misassembled.
9. Correct the end play by changing the selective washer (616).

J 29837-A Output Shaft Support Fixture. See Special Tools and Equipment .

1. Remove the reaction sun gear (673) and the thrust washer (674).
2. Remove the low and reverse support retainer ring (676).
3. Remove the J 29837-A . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
4. Push on the output shaft (687) in order to loosen the low and reverse clutch support (679).
5. Remove the low and reverse clutch support (679).
6. Remove the output shaft (687).
7. Remove the low and reverse clutch support retainer spring (680).
8. Remove the reaction carrier assembly (681).
9. Remove the following components: The low and reverse clutch fiber plate assembly (682C) The low and reverse clutch steel plates (682D) The low and reverse clutch selective plate (682B) The low and reverse clutch waved plate (682A)
10. Remove the following components: The thrust bearing assembly (reaction carrier support) (683) The internal reaction gear (684) The internal reaction gear support (685) The reaction gear support bearing (692)

J 29714-A Servo Cover Compressor. See Special Tools and Equipment .

1. Install the 2-4 servo into the case.
2. Install oil pan with only four bolts to align pan to case.
3. Use the J 29714-A in order to compress the servo cover. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
4. Install the servo cover retaining ring.
5. Remove oil pan.
6. Pour solvent into the accumulator bore until the channel is filled. Watch for leaks in the case channel.
7. If leakage from the oval shaped hole is observed, replace the third accumulator retainer and ball assembly.

J 36850 Transjel Lubricant

1. Install the reaction carrier/support thrust bearing assembly (683) into the internal reaction gear support (685).
2. Install the reaction gear support to case bearing (692) onto the internal reaction gear support (685). Retain the bearing using J 36850 or equivalent.
3. Install the internal reaction gear (684) and the internal reaction gear support (685) into the case.
4. Install the reaction carrier assembly (681) into the internal reaction gear.

Tools Required

1. J 8001 Dial Indicator Set
2. J 26900-13 Magnetic Indicator Base

1. Inspect the low and reverse clutch plates for the following conditions: Composition material wear Composition material heat damage Composition material delamination Steel plates heat damage Steel plates surface finish damage
2. Stack the low and reverse clutch plate assembly on a flat surface in the following order: One waved plate (682A) Five fiber plate assemblies (682C) and four steel plates (682D), starting with one fiber plate assembly and alternating with steel Low and reverse clutch support (679)
3. Using the J 8001 and the J 26900-13 , measure the height of the clutch pack from the work surface to the top of the low and reverse clutch support.
4. Refer to «Low and Reverse Clutch Spacer Plate Selection»(ref-187261-S28163998822005083100000) in order to select the proper thickness of the low and reverse clutch selective spacer plate (682B).
5. Install the proper selective spacer plate (682B) between the wave plate (682A) and the first fiber plate assembly (682C), with the identification side up. The overall height for the clutch pack including the selective spacer plate should be 29.22-29.90 mm (1.15-1.18 in).

J 36850 Transjel Lubricant

1. Install the reaction sun shell (670) into the reaction sun gear.
2. Depending on model, install either a thrust bearing (669A) or thrust washer (669B) as follows: Install thrust washer (669B), tangs down into the holes in the reaction sun shell. Install the thrust bearing (669A) using J 36850 onto the reaction carrier shaft, tangs up, towards the shaft.
3. Install the input internal gear (664) and reaction carrier shaft (666) assembly into the sun gear shell. Index the reaction carrier shaft spline into the reaction carrier.
4. Install the input carrier to reaction shaft thrust bearing assembly (663).

J 29837-A Output Shaft Support Fixture. See Special Tools and Equipment .

1. Install the output shaft (687).
2. Install the J 29837-A . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .

Forward Clutch Piston Travel Check

1. Use feeler gauges to check the forward clutch plate travel. Check travel between the forward clutch backing plate retainer ring (651) and the forward clutch selective backing plate (650). The forward clutch plate travel should be: Specification: 298 mm/300 mm Torque Converter- 0.866-1.876 mm (0.034-0.074 in)
2. Select the proper forward clutch selective backing plate (650) to obtain the correct travel. Refer to «Forward Clutch Backing Plate Selection»(ref-187261-S30620323532005083100000) .

3-4 Clutch Plate Travel Check

1. Use feeler gauges to check the 3rd and 4th clutch plate travel.
2. Check the travel between the selective backing plate (655) and the first fiber plate assembly (654A). The 3rd and 4th clutch plate travel should be 0.90-2.10 mm (0.035-0.083 in).
3. Select the proper 3rd and 4th clutch selective backing plate to obtain the correct travel. Refer to «Third and Fourth Clutch Backing Plate Selection»(ref-187261-S06755871892005083100000) .

Reverse Input Clutch Plate Travel Check

1. Apply an evenly distributed load to the clutch pack.
2. Use feeler gauges to check the reverse input clutch plate travel.
3. Check the travel between the selective backing plate and the reverse input clutch retainer ring. Clutch Plate Travel Specifications: The reverse input clutch plate travel should be 1.02-1.94 mm (0.040-0.076 in).
4. Select the proper selective backing plate to obtain the correct travel. Refer to «Reverse Input Clutch Backing Plate Selection»(ref-187261-S01188516852005083100000) .

1. Measure the oil pump rotor (212) thickness.
2. Measure the oil pump slide (203) thickness.

J 21368 Pump Body and Cover Alignment Band. See Special Tools and Equipment .

1. Place the oil pump cover onto the oil pump body and put stator shaft through a hole in the bench.
2. Install the pump cover bolts (223) finger tight only.
3. Install the J 21368 . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
4. Tighten the pump cover bolts (223). Tighten: Tighten the bolts to 24 N.m (18 lb ft).
5. Remove the J 21368 . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .

Tools Required

1. J 25022 End Play Fixture Adapter. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
2. J 34725 End Play Checking Adapter. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
3. J 43205 End Play Fixture Adapter (300 mm). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
4. J 24773-A Oil Pump Remover. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
5. J 8001 Dial Indicator Set
6. J 25025-7A Dial Indicator Post. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .

1. Install an end play fixture adapter. Use J 25022 for a 245 mm and 258 mm turbine shaft (1). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) . Use J 34725 for a 298 mm turbine shaft (2). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) . Use J 43205 for a 300 mm turbine shaft (3). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
2. Install the J 24773-A . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
3. Remove an oil pump bolt.
4. Install J 25025-7A (or a 278 mm or 11 in bolt) and lock nut. See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
5. Install J 8001 .
6. Set the J 8001 to zero.
7. Pull up on J 24773-A . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) . Proper end play should be 0.13-0.92 mm (0.005-0.036 in).
8. The selective washer (616), which controls the end play, is located between the input housing (621) and the thrust bearing (615) on the oil pump hub. If the end play measurement is incorrect, refer to the «End Play Specifications»(ref-187261-S05710402912005083100000) table. Choose a new selective washer (616) based on the original selective washer and the information contained in the table. If the dial indicator shows no end play, the selective washer (616) and thrust bearing (615) may have been misassembled.
9. Correct the end play by changing the selective washer (616).

J 41510 T-50 Plus Bit. See Special Tools and Equipment .

1. Install the converter housing (102).
2. Install the converter housing bolts (94) to the transmission case. Use the J 41510 . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) . Tighten: Tighten the converter housing bolts (94) to 65-75 N.m (48-55 lb ft).

Cleaning Procedure

1. Clean all the valves, springs, bushings, and the control valve body in clean solvent.
2. Dry all the parts using compressed air.

J 22269-01 Accumulator and Servo Piston Remover. See Special Tools and Equipment .

1. Use a J 22269-01 to compress the second apply piston assembly (17). See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
2. Remove the second apply piston retaining ring (14).
3. Remove the servo cushion spring retainer (15), the servo cushion outer spring (16) and the servo cushion inner spring (105) (model dependent).

J 33037 2-4 Intermediate Band Apply Pin Gauge. See Special Tools and Equipment .

1. Install the band apply pin and the J 33037 . See «Special Tools and Equipment»(ref-187261-S18358459572005083100000) .
2. Install the servo cover retaining ring to secure the tool.
3. Apply 11 N.m (98 lb in) torque. If the white line appears in the gauge slot (1), the pin length is correct.
4. If a new pin is needed, refer to «2-4 Servo Pin Selection»(ref-187261-S04543979392005083100000) in order to determine the correct pin length.

J 21366 Converter Holding Strap

1. Install the torque converter.
2. Install the J 21366 .

J 8763-B Holding Fixture and Base. See Special Tools and Equipment .

Scheme 232

Remove the transmission from the J 8763-B . See Special Tools and Equipment .

Park - Engine Running

With the gear selector lever in the PARK (P) position and the engine running, the line pressure from the oil pump assembly is directed to various components in the valve body and the oil pump.

Pressure Regulator Valve

The pressure regulator valve regulates the oil pump output (line pressure) in response to the signal fluid pressure, the spring force and the line pressure acting on the end of the valve. The line pressure is routed through the valve and into both the converter feed and the decrease fluid circuits. Regulated line pressure is also directed to the manual valve, the converter clutch valve, the actuator feed limit valve, and the regulated apply valve.

Pressure Relief Valve

Controlled by spring force, this checkball limits the maximum value of the line pressure. When the line pressure reaches this limiting value, fluid is exhausted past the ball and returns to the sump.

Line Pressure Tap

The line pressure tap provides a location to measure the line pressure with a fluid pressure gauge.

Actuator Feed Limit Valve

Biased by spring force and orificed AFL fluid, it limits the maximum value of line pressure entering the AFL fluid circuit. Below this limiting value, the AFL fluid pressure equals the line pressure. The AFL fluid is routed to the pressure control solenoid valve, the 3-2 control solenoid valve, the TCC PWM solenoid valve, the 1-2 and 2-3 shift solenoid valves, and the 2-3 shift valve train.

Pressure Control (PC) Solenoid Valve

Controlled by the powertrain control module (PCM), the PC solenoid valve regulates the filtered AFL fluid into the torque signal fluid pressure. The PCM controls this regulation by varying the current value to the PC solenoid valve in relation to the throttle position and other vehicle operating conditions.

TCC Solenoid Valve

Under normal operating conditions, the PCM keeps the normally open TCC solenoid valve de-energized (OFF). Converter feed fluid exhausts through the open TCC solenoid valve, and spring force keeps the converter clutch apply valve in the release position.

Converter Clutch Valve

Held in the release position by spring force, it directs converter feed fluid into the release fluid circuit. Also, fluid returning from the converter in the apply fluid circuit is routed through the valve and into the cooler fluid circuit.

Manual Valve

Controlled by the selector lever and the manual shaft, the manual valve is in the Park (P) position and directs the line pressure into the PR (Park/Reverse) fluid circuit. Line pressure is blocked from entering any other fluid circuit at the manual valve.

Lo and Reverse Clutch Piston

The PR fluid seats the lo and reverse clutch checkball (#10) and is orificed to the outer area of the piston. Orificing the PR fluid around the #10 checkball helps control the lo and reverse clutch apply. Also, Lo/reverse fluid pressure from the lo overrun valve acts on the inner area of the lo and reverse clutch piston in order to increase the clutch holding capacity.

Lo Overrun Valve

The PR fluid pressure moves the valve against the spring force and fills the Lo/reverse fluid circuit. Lo/reverse fluid is orificed (323) back to the lo overrun valve in order to assist the PR fluid in moving the valve against the spring force. The spring force provides a time delay for the PR fluid filling the Lo/reverse fluid circuit. The Lo/reverse fluid is routed to the inner area of the lo and reverse clutch piston in order to increase the holding capacity of the clutch.

Shift Solenoid Valves (1-2 and 2-3)

Both shift solenoid valves, which are normally open, are energized by the PCM and block fluid from exhausting. This maintains the signal A fluid pressure at the 1-2 shift solenoid valve and signal B fluid pressure at the 2-3 shift solenoid valve.

Shift Valves (1-2, 2-3 and 3-4)

Signal A fluid pressure holds the 1-2 shift valve in the downshift position and the 3-4 valve in the upshift (first and fourth gear) position. The signal B fluid pressure from the 2-3 shift solenoid valve holds the 2-3 shift valve train in the downshift position.

Scheme 233

Neutral - Engine Running

When the gear selector lever is moved to the Neutral position (N) from the Reverse position, the following changes occur to the transmission hydraulic and electrical systems.

In the Neutral position, the manual valve blocks the line pressure from entering any other fluid circuits. Reverse and PR fluids exhaust past the manual valve.

PR and Lo/reverse fluids exhaust from the piston, thereby releasing the lo and reverse clutch plates. Exhausting PR fluid unseats the lo and reverse clutch checkball (#10) for a quick exhaust.

Spring force closes the valve when the PR fluid pressure exhausts. Lo/reverse fluid exhausts through the valve, into the Lo/1st fluid circuit, past the 1-2 shift valve, into the Lo fluid circuit and through an exhaust port at the manual valve.

Reverse Input Clutch Piston

Reverse input fluid pressure exhausts from the piston, through the boost valve, past the #3 checkball and to the manual valve. With the reverse input fluid exhausted, the reverse input clutch plates are released and the transmission is in Neutral.

Reverse Abuse Valve

Reverse fluid pressure exhausts and spring force closes the valve.

Boost Valve

Reverse input fluid pressure exhausts and line pressure returns to the normal operating range as in the Park and Overdrive positions.

Reverse Input Checkball (#3)

Exhausting reverse input fluid unseats the ball for a quick exhaust through the reverse fluid circuit and past the manual valve.

Overdrive Range, First Gear

When the gear selector lever is moved to the Overdrive position, from the neutral position, the following changes occur to the transmission's hydraulic and electrical systems

Line pressure flows through the manual valve and fills the D4 fluid circuit. All other fluid circuits remain empty with the manual valve in the Overdrive position.

Forward Clutch Applies

or

Forward Clutch Accumulator Checkball (#12)

D4 fluid pressure seats the checkball and is orificed (#22) into the forward clutch feed fluid circuit. This orifice helps control the forward clutch apply rate.

Forward Clutch Accumulator Piston

Forward clutch feed fluid pressure moves the piston against spring force. This action absorbs some of the initial increase of forward clutch feed fluid pressure to cushion the forward clutch apply.

Forward Clutch Abuse Valve

D4 fluid pressure acts on the valve opposite of spring force. At engine speeds greater than idle, D4 fluid pressure increases and moves the valve against spring force (as shown). D4 fluid can then quickly fill the forward clutch feed fluid circuit, thereby bypassing the control of orifice #22 and providing a faster apply of the forward clutch. Otherwise, with increased throttle opening and engine torque, the clutch may slip during apply.

1-2 Shift Solenoid (SS) Valve

Energized (ON) as in Neutral, the normally open solenoid is closed and blocks signal A fluid from exhausting through the solenoid. This maintains pressure in the signal A fluid circuit.

2-3 Shift Solenoid (SS) Valve

Energized (ON) as in Neutral, the normally open solenoid is closed and blocks signal B fluid from exhausting through the solenoid. This maintains signal B fluid pressure at the solenoid end of the 2-3 shift valve.

2-3 Shift Valve Train

Signal B fluid pressure at the solenoid end of the 2-3 shift valve holds the valve train in the downshifted position against AFL fluid pressure acting on the 2-3 shift valve. In this position, the 2-3 shuttle valve blocks AFL fluid from entering the D432 fluid circuit. The D432 fluid circuit is open to an exhaust port past the valve.

1-2 Shift Valve

Signal A fluid pressure holds the valve in the downshifted position against spring force. In the First gear position, the valve blocks D4 fluid from entering the 2nd fluid circuit.

Accumulator Valve

Biased by torque signal fluid pressure, spring force and orificed accumulator fluid pressure at the end of the valve, the accumulator valve regulates D4 fluid into accumulator fluid pressure. Accumulator fluid is routed to both the 1-2 and 3-4 accumulator assemblies in preparation for the 1-2 and 3-4 upshifts respectively.

Rear Lube (All Except Y-Car)

D4 fluid is routed through an orifice cup plug (#24) in the rear of the transmission case to feed the rear lube fluid circuit.

Remember that the PC solenoid valve continually varies torque signal fluid pressure in relation to throttle position and vehicle operating conditions. This provides a precise control of line pressure.

3-2 Control Solenoid Valve

The PCM keeps the solenoid OFF in First gear and the normally closed solenoid blocks filtered AFL fluid from entering the 3-2 signal fluid circuit.

Overdrive Range, Second Gear

As vehicle speed increases and other operating conditions are appropriate, the PCM de-energizes the 1-2 shift solenoid valve in order to shift the transmission to second gear.

De-energized (turned OFF) by the PCM, the normally open solenoid opens and signal A fluid exhausts through the solenoid.

Energized (ON) as in first gear, the 2-3 shift solenoid valve blocks signal B fluid from exhausting through the solenoid. This maintains signal B fluid pressure at the solenoid end of the 2-3 shift valve.

Without signal A fluid pressure, spring force moves the valve into the upshift position. D4 fluid is routed through the valve and fills the 2nd fluid circuit.

1-2 Shift Checkball (#8)

The 2nd fluid pressure seats the #8 checkball, flows through orifice #16, and fills the 2nd clutch fluid circuit. This orifice helps control the 2-4 band apply rate.

1-2 Accumulator

The 2nd clutch fluid pressure also moves the 1-2 accumulator piston against the spring force and the accumulator fluid pressure. This action absorbs the initial 2nd clutch fluid pressure in order to cushion the 2-4 band apply rate. Also, the movement of the 1-2 accumulator piston forces some accumulator fluid out of the accumulator assembly. This accumulator fluid is routed back to the accumulator valve.

The accumulator fluid forced out of the 1-2 accumulator is orificed (#30) to the end of the accumulator valve. This pressure moves the valve against the spring force and the torque signal fluid pressure in order to regulate the exhaust of excess accumulator fluid. This regulation provides additional control for the 2-4 band apply rate. The fluid circuit shows the exhaust of the accumulator fluid during the shift by the arrow directions in the accumulator fluid circuit.

The signal B fluid pressure from the 2-3 shift solenoid valve holds the valve train in the downshift position. The 2nd fluid is routed through the 2-3 shuttle valve and fills the servo feed fluid circuit.

3-4 Relay Valve and 4-3 Sequence Valve

Spring force holds these valves in the downshift position (first, second and third gear positions). The 2nd fluid is blocked by the 3-4 relay valve and the servo feed fluid is blocked by both valves in preparation for a 3-4 upshift.

3-2 Downshift Valve

Spring force holds the valve closed, blocking the 2nd fluid and the 2nd clutch fluid. This valve is used in order to help control the 3-2 downshift.

In second gear, the PCM energizes the normally closed solenoid. This opens the AFL fluid circuit to fill the 3-2 signal fluid circuit.

3-2 Control Valve

The 3-2 signal fluid pressure moves the valve against the spring force. This action does not affect the transmission operation in second gear.

3-4 Shift Valve

Signal A fluid pressure exhausts and spring force moves the valve into the downshift position (second and third gear positions).

Under normal operating conditions, in Overdrive Range-Second Gear, the PCM keeps the normally open TCC solenoid valve de-energized. Converter feed fluid exhausts through the open solenoid, and spring force keeps the converter clutch apply valve in the release position.

Scheme 234

Overdrive Range, Third Gear

As vehicle speed increases further and other vehicle operating conditions are appropriate, the PCM de-energizes the normally open 2-3 shift solenoid valve in order to shift the transmission into Third gear.

De-energized (turned OFF) by the PCM, the solenoid opens and actuator feed limit signal B fluid exhausts through the solenoid.

Note: AFL fluid continues to feed signal B fluid to the solenoid through orifice #29. However, the exhaust port through the solenoid is larger than orifice #29 to prevent a buildup of pressure in the signal B fluid circuit at the solenoid end of the 2-3 shift valve. Exhausting signal B fluid is represented by the arrows through the solenoid.

AFL fluid pressure at the 2-3 shift valve moves the valve train toward the solenoid. In the upshifted position, the following changes occur

1. AFL fluid is routed through the 2-3 shift valve and fills the D432 fluid circuit.
2. 2nd fluid is blocked from entering the servo feed fluid circuit and is orificed (#28) into the 3-4 signal fluid circuit. This orifice helps control the 3-4 clutch apply rate.
3. Servo feed fluid exhausts past the valve into the 3-4 accumulator fluid circuit and through an exhaust port at the 3-4 relay valve.

3-4 Clutch Exhaust Checkball (#4)

3-4 signal fluid unseats the ball and enters the 3-4 clutch fluid circuit.

3-4 Clutch Piston

3-4 clutch fluid pressure moves the piston to apply the 3-4 clutch plates and obtain 3rd gear. However, the 2-4 band must release as the 3-4 clutch applies.

3rd Accumulator Checkball (#2)

3-4 clutch fluid pressure unseats the ball and fills the 3rd accumulator fluid circuit.

3rd Accumulator Exhaust Checkball (#7)

3rd accumulator fluid seats the ball against the orificed exhaust and is routed to the released side of the 2nd apply piston. Before the #7 checkball seats, air in the 3rd accumulator fluid circuit is exhausted through the orifice.

3-4 clutch fluid pressure moves the valve against spring force. This opens the valve and allows 2nd fluid to feed the 2nd clutch fluid circuit through the valve.

3-2 Control Solenoid Valve and 3-2 Control Valve

The solenoid remains open and routes AFL fluid into the 3-2 signal fluid circuit. 3-2 signal fluid pressure holds the 3-2 control valve against spring force, thereby blocking the 3rd accumulator and 3-4 clutch fluid circuits.

1-2 Shift Solenoid (SS) Valve and 1-2 Shift Valve

The 1-2 SS valve remains de-energized and signal A fluid is exhausted through the solenoid. Also, D432 fluid pressure from the 2-3 shift valve assists spring force to hold the 1-2 shift valve in the upshifted position.

Spring force holds the valve in the downshifted position, blocking 3-4 clutch fluid in preparation for a 3-4 upshift.

Under normal operating conditions, in Overdrive Range-Third Gear, the PCM keeps the normally open TCC solenoid valve de-energized. Converter feed fluid exhausts through the open solenoid, and spring force keeps the converter clutch apply valve in the release position. However, at speeds above approximately 121 km/h (75 mph), with the transmission still in third gear, the PCM will command TCC apply in third gear. Refer to Overdrive Range, Fourth Gear - Torque Converter Clutch (TCC) Applied for more information on TCC apply.

Scheme 235

Energized (turned ON) by the PCM, the normally open solenoid closes and blocks signal A fluid from exhausting through the solenoid. This creates pressure in the signal A fluid circuit.

De-energized (OFF) as in third gear, the 2-3 shift solenoid valve exhausts signal B fluid through the solenoid.

D432 fluid pressure from the 2-3 shift valve and spring force hold the valve in the upshift position against signal A fluid pressure.

Signal A fluid pressure moves the valve into the upshift position against the spring force. In this position, the valve routes 3-4 signal fluid into the 4th signal fluid circuit.

4th signal fluid pressure moves both valves into the upshift (fourth gear) position against the spring force acting on the 4-3 sequence valve. This causes the following changes

1. Orificed (#7) 2nd fluid is routed through the 3-4 relay valve and into the servo feed fluid circuit.
2. Servo feed fluid is routed through the 4-3 sequence valve and into the 4th fluid circuit.
3. 3-4 accumulator fluid routed from the 2-3 shuttle valve is blocked by both valves.

The valve train remains in the upshift position with the AFL fluid pressure acting on the 2-3 shift valve. In addition to its operation third gear, the 2-3 shift valve directs servo feed fluid into the 3-4 accumulator fluid circuit.

3-4 Accumulator Checkball (#1)

The accumulator fluid forced from the accumulator unseats the #1 checkball and enters the accumulator fluid circuit. This fluid is routed to the accumulator valve. This is shown by the arrow directions in the fluid circuit.

Accumulator fluid forced from the 3-4 accumulator is orificed to the end of the accumulator valve. This fluid pressure, in addition to spring force and torque signal fluid pressure, regulates the exhaust of excess accumulator fluid pressure through the middle of the valve. This regulation helps control the 2-4 band apply feel.

The solenoid remains open and routes AFL fluid into the 3-2 signal fluid circuit. 3-2 signal fluid pressure holds the 3-2 control valve against spring force, thereby blocking the 3rd accumulator and 3-4 clutch fluid circuits.

When operating conditions are appropriate, the PCM energizes the normally open TCC solenoid valve. This closes the solenoid, blocks the converter feed fluid from exhausting, and creates pressure in the converter feed fluid circuit at the converter clutch apply valve and TCC solenoid valve.

Converter Clutch Apply Valve

Converter feed fluid pressure moves the valve against spring force and into the apply position. In this position, release fluid is open to an exhaust port, and regulated apply fluid fills the apply fluid circuit. Converter feed fluid is routed through the converter clutch apply valve to feed the cooler fluid circuit.

TCC Apply Checkball (#9)

Release fluid, exhausting from the converter, seats the #9 checkball located in the end of the turbine shaft, and is orificed around the ball. Orificing the exhausting release fluid controls the converter clutch apply rate, along with the TCC PWM solenoid valve.

TCC PWM Solenoid Valve

The torque converter clutch pulse width modulation (TCC PWM) solenoid valve controls the regulated apply valve position. This is done through the use of pulse width modulation (duty cycle operation). The solenoid duty cycle is controlled by the PCM in relation to vehicle operating conditions and regulates actuator feed limit (AFL) fluid into the CC signal circuit, through the #9 orifice, and to the isolator valve. This controls line pressure flow through the regulated apply valve, into the regulated apply circuit, and provides a smooth engagement of the TCC.

Scheme 236

Overdrive Range, 4-3 Downshift

When the transmission is operating in fourth gear, a forced 4-3 downshift occurs if there is a significant increase in throttle position. At minimum throttle, the vehicle speed decreases gradually (coastdown) and the PCM commands a 4-3 downshift. The PCM also initiates a forced 4-3 downshift when the throttle position remains constant but engine load is increased, such as driving up a steep incline. To achieve a 4-3 downshift, the PCM de-energizes the 1-2 shift solenoid valve and the following changes occur to the transmission's electrical and hydraulic systems

De-energized by the PCM, the normally open solenoid opens and signal A fluid exhausts through the solenoid.

As in Fourth gear, D432 fluid pressure and spring force hold the valve in the upshift position.

With the signal A fluid pressure exhausted, the spring force moves the valve into the downshift position. In this position, the valve blocks the 3-4 signal fluid and the 4th signal fluid exhausts past the valve.

These valves control the timing of the 2-4 band release. With the 4th signal fluid pressure exhausted, the 3-4 accumulator fluid pressure moves the 3-4 relay valve into the third gear position. This opens the 3-4 accumulator fluid to an orificed exhaust (#5) past the 3-4 relay valve (shown by red arrows). Because the exhaust is orificed, the 3-4 accumulator fluid pressure momentarily holds the 4-3 sequence valve against spring force before completely exhausting.

When the exhausting 3-4 accumulator fluid pressure decreases sufficiently, the spring force moves the 4-3 sequence valve into the third gear position as shown. This opens both the 3-4 accumulator and the 4th fluid circuits to a quick exhaust past the 4-3 sequence valve. In this position the valve blocks the 2nd fluid from entering the servo feed fluid circuit.

As the accumulator fluid fills the 3-4 accumulator, it seats the #1 checkball and is forced through orifice #18. This orifice controls the rate at which accumulator fluid pressure fills the 3-4 accumulator and the 3-4 accumulator fluid exhausts from the accumulator assembly.

Biased by torque signal fluid pressure and spring force, the accumulator valve regulates the D-4 fluid into the accumulator fluid circuit.

This solenoid remains de-energized as in fourth gear and the signal B fluid exhausts through the solenoid.

The AFL fluid pressure at the 2-3 shift valve holds the valves in the upshift position. This allows the servo feed fluid to exhaust through the valve, into the 3-4 accumulator fluid circuit and past the 4-3 sequence valve.

The PCM de-energizes the TCC solenoid valve, and operates the duty cycle of the TCC PWM solenoid valve to release the converter clutch for a smooth disengagement, prior to initiating the 4-3 downshift.

Remember that the PC solenoid valve continually adjusts the torque signal fluid pressure in relation to the various PCM input signals (mainly the throttle position).

Scheme 237

Overdrive Range, 3-2 Downshift

Similar to a forced 4-3 downshift, a forced 3-2 downshift can occur because of minimum throttle (coastdown conditions), heavy throttle or increased engine load. In order to achieve a forced 3-2 downshift, the PCM energizes the 2-3 shift solenoid valve and the following changes occur

Energized by the PCM, the normally open solenoid closes and blocks the signal B fluid from exhausting through the solenoid. This creates pressure in the signal B fluid circuit at the solenoid end of the 2-3 shift valve.

The signal B fluid pressure from the shift solenoid moves both valves to the downshift position against AFL fluid pressure acting on the 2-3 shift valve. This causes the following changes

1. The AFL fluid is blocked from the D432 fluid circuit and the D432 fluid exhausts past the 2-3 shuttle valve.
2. The 2nd fluid is blocked from feeding the 3-4 signal fluid circuit and the 2nd fluid is routed into the servo feed fluid circuit.
3. The 3-4 signal fluid is exhausted past the valve. The 3-4 clutch fluid and the 3rd accumulator fluid, which were fed by the 3-4 signal fluid, also exhaust.

The 3-4 clutch fluid exhausts from the piston and the 3-4 clutch plates are released.

Exhausting 3-4 clutch fluid seats the #4 checkball and is forced through orifice #13. This orifice controls the 3-4 clutch fluid exhaust and the 3-4 clutch release rate.

3-2 Downshift Valve and 1-2 Upshift Checkball (#8)

The 3-4 clutch fluid exhausts from the valve and the spring force moves the valve into the second gear position. However, before the spring force overcomes the exhausting 3-4 clutch fluid pressure, the 2nd fluid feeds the 2nd clutch fluid circuit through the valve. This bypasses the control of orifice #16 at the #8 checkball and provides a faster 2-4 band apply. Remember that the #8 checkball and orifice #16 are used to help control the 2-4 band apply during a 1-2 upshift.

Downshift Timing and Control

At higher vehicle speeds, the 2-4 band apply must be delayed to allow the engine speed RPM to increase sufficiently for a smooth transfer of engine load to the 2-4 band. Therefore, exhaust of the 3rd accumulator fluid must be delayed. However, at lower speeds the band must be applied quickly. In order to provide for the varying requirements for the 2-4 band apply rate, the exhausting 3rd accumulator fluid is routed to both the 3rd accumulator checkball (#2) and the 3-2 control valve.

The exhausting 3rd accumulator fluid seats the #2 checkball and is forced through orifice #12. This fluid exhausts through the 3-4 clutch and the 3-4 signal fluid circuits and past the 2-3 shift valve. Orifice #12 slows the exhaust of the 3rd accumulator fluid and delays the 2-4 band apply rate.

These components are used to increase the exhaust rate of 3rd accumulator fluid, as needed, depending on the vehicle speed.

The 3-2 control solenoid valve is a normally closed On/Off solenoid controlled by the PCM. The PCM controls the solenoid state during a 3-2 downshift according to vehicle speed.

Low Speed

1. At lower vehicle speeds, the PCM operates the 3-2 control solenoid valve in the Off position.
2. In the Off position the solenoid blocks actuator feed limit fluid pressure from the 3-2 control valve.
3. With no actuator feed limit fluid pressure, the 3-2 control valve spring force keeps the valve open to allow a faster exhaust of 3rd accumulator fluid through orifice #14 into the 3-4 clutch fluid circuit.
4. A faster exhaust of the 3rd accumulator exhaust fluid provides a faster apply of the 2-4 band, as needed at lower vehicle speeds.

High Speed

1. At high vehicle speed, the PCM operates the 3-2 control solenoid valve in the On position allowing actuator feed limit fluid to pass through the solenoid. This pushes the 3-2 control valve into the closed position.
2. This action permits a slow apply of the 2-4 band by blocking off 3rd accumulator exhaust fluid from entering the 3-4 clutch fluid circuit through orifice #14.
3. This allows the engine speed to easily come up to the necessary RPM before the 2-4 band is applied.

After the downshift is completed, the #7 checkball unseats and allows the residual fluid in the 3rd accumulator fluid circuit to exhaust.

Remember that the PC solenoid valve continually adjusts torque signal fluid in relation to the various PCM input signals (mainly the throttle position).

Scheme 238

Manual Third Gear

A manual 4-3 downshift is available to increase vehicle performance when the use of only three gear ratios is desired. Manual Third gear range also provides engine braking in Third gear when the throttle is released. A manual 4-3 downshift is accomplished by moving the selector lever into the Manual Third (D) position. This moves the manual valve and immediately downshifts the transmission into Third gear. Refer to Overdrive Range, 4-3 Downshift for a complete description of a 4-3 downshift. In Manual Third, the transmission is prevented, both hydraulically and electronically, from shifting into Fourth gear. The following information explains the additional changes during a manual 4-3 downshift as compared to a forced 4-3 downshift.

The selector lever moves the manual shaft and manual valve into the Manual Third position (D). This allows line pressure to enter the D3 fluid circuit.

When Manual Third is selected, the PCM de-energizes the 1-2 SS valve to immediately downshift the transmission into Third gear. This electronically prevents Fourth gear.

D3 fluid pressure assists spring force to keep the valve in the downshifted position against the signal A fluid circuit. In this position, the valve blocks 3-4 signal fluid and the 4th signal fluid circuit is open to an exhaust port past the valve. Therefore, with D3 fluid pressure assisting spring force, Fourth gear is hydraulically prevented.

With the 2-3 SS valve de-energized and open, actuator feed limit (AFL) fluid acting on the 2-3 shift valve holds both valves in the upshifted position. This allows D3 fluid to feed the overrun fluid circuit through the 2-3 shift valve.

Overrun Clutch Feed Checkball (#5)

Overrun fluid pressure seats the ball against the empty D2 fluid circuit.

Overrun Clutch Control Checkball (#6)

Overrun fluid pressure seats the #6 checkball and is orificed (#20) to fill the overrun clutch feed fluid circuit. This orifice controls the overrun clutch apply rate.

4th signal fluid pressure is exhausted from the end of the 3-4 relay valve. Overrun clutch feed fluid pressure assists spring force and closes both valves. This allows overrun clutch feed fluid to flow through the 4-3 sequence valve and fill the overrun clutch fluid circuit.

Overrun Clutch Piston

Overrun clutch fluid pressure moves the piston to apply the overrun clutch plates. The overrun clutch plates provide engine compression braking in Manual Third - Third Gear.

Overrun Clutch Air Bleed Checkball

This ball and capsule is located in the overrun clutch fluid circuit in the oil pump. It allows air to exhaust from the circuit as fluid pressure increases and also allows air into the circuit to displace the fluid when the clutch releases.

The PC solenoid valve operates in the same manner as Overdrive Range, regulating in response to throttle position and other vehicle operating conditions.

Manual Third - First and Second Gears: Overrun Clutch Released

In Manual Third, the transmission upshifts and downshifts normally between First, Second and Third gears. However, in First and Second gears, the 2-3 SS valve is energized and the 2-3 shift valve train is in the downshifted position. The 2-3 shift valve blocks D3 fluid from entering the overrun fluid circuit and opens the overrun fluid circuit to an exhaust port at the valve. This prevents overrun clutch apply and engine compression braking in Manual Third-First and Second Gears.

Scheme 239

Manual Second Gear

A manual 3-2 downshift can be accomplished by moving the gear selector lever into the Manual Second (2) position when the transmission is operating in third gear. This causes the transmission to shift immediately into second gear regardless of vehicle operating conditions. Also, the transmission is prevented from operating in any other gear, first, third or fourth. The following information explains the additional changes during a manual 3-2 downshift, as compared to a forced 3-2 downshift. Some vehicles in manual second gear will start out in first gear, while other vehicles will have a second gear start. Refer to the owners manual for specific applications.

The selector lever moves the manual shaft and the manual valve into the manual second (2) position. This allows the line pressure to enter the D2 fluid circuit.

The PCM energizes the 2-3 SS valve and the AFL fluid pressure holds the 2-3 shift valve in the downshift position. This electronically prevents operation of the third and fourth gears.

The D2 fluid is routed between the 2-3 shuttle and the 2-3 shift valves and causes the following

1. Regardless of the operating conditions, the D2 fluid pressure holds the 2-3 shift valve in the downshift position against the AFL fluid pressure.
2. The 2nd fluid is blocked from entering the 3-4 signal fluid circuit and the 3-4 signal fluid circuit is open to an exhaust port at the valve.
3. The 3-4 clutch cannot apply with the 3-4 signal fluid exhausted. Therefore, third and fourth gears are hydraulically prevented.
4. The 2nd fluid feeds the servo feed fluid circuit, but the 2nd fluid circuit has no function in manual second.
5. The AFL fluid is blocked by the 2-3 shift valve and the D432 fluid circuit is exhausted through the valve.
6. The overrun fluid is exhausted through the 2-3 shuttle valve.

The 1-2 SS valve is OFF, the signal A fluid exhausts through the solenoid and the spring force holds the valve in the upshifted position.

First Gear Prevented

The prevention of first gear is controlled electronically by the PCM through the 1-2 SS valve. The PCM keeps the 1-2 SS valve de-energized, regardless of the vehicle operating conditions when the TFP manual valve position switch signals manual second gear range. This keeps signal A fluid exhausted and the spring force holds the 1-2 shift valve in the upshift position.

Orificed D2 fluid pressure seats the #5 checkball against the empty overrun clutch fluid circuit. This is done simultaneously with the overrun clutch fluid exhausting so that there is a continuous fluid supply to the overrun clutch feed fluid circuit.

A continuous supply of fluid pressure is routed to the piston in order to keep the overrun clutch plates applied.

The PCM output signal to the PC solenoid valve increases the operating range of torque signal fluid pressure in manual second. This provides the increased line pressure for the additional torque requirements during the engine compression braking and increased engine loads.

Scheme 240

Manual First Gear

A manual 2-1 downshift can be accomplished by moving the gear selector lever into the manual first (1) position when the transmission is operating in second gear. The downshift to first gear is controlled electronically by the PCM. The PCM will not energize the 1-2 shift solenoid valve to initiate the downshift until the vehicle speed is below approximately 48 to 56 km/h (30 to 35 mph). Above this speed, the transmission operates in a manual first-second gear state. The following text explains the manual 2-1 downshift.

The selector lever moves the manual shaft and the manual valve into the manual first (1) position. This allows the line pressure to enter the Lo fluid circuit.

In both first and second gears, this solenoid is energized and maintains the signal B fluid pressure at the solenoid end of the 2-3 shift valve train.

Held in the downshift position by the signal B fluid pressure from the solenoid, the valve train blocks the AFL fluid from entering the D432 fluid circuit. The D432 fluid circuit is open to exhaust past the valve.

Below approximately 48 to 56 km/h (30 to 35 mph) the PCM energizes the normally open solenoid. This blocks the signal A fluid pressure from exhausting through the solenoid and creates the pressure in the signal A fluid circuit. Above this speed, the PCM keeps the solenoid de-energized and the transmission operates in manual first-second gear.

Signal A fluid pressure moves the valve against the spring force and into the downshift position. In this position, Lo fluid from the manual valve is routed into the Lo/1st fluid circuit and D4 fluid is blocked from entering the 2nd fluid circuit. The 2nd fluid exhausts through an orifice and an annulus exhaust port past the valve. This orifice (#26) helps control the 2-4 band release during a 2-1 downshift.

As the accumulator fluid is filling the 1-2 accumulator assembly, the accumulator valve regulates the D4 fluid into the accumulator fluid circuit. This regulation, biased by torque signal fluid pressure and spring force, helps control the movement of the 1-2 accumulator piston. The 2nd clutch fluid exhaust, and the 2-4 band release.

1-2 Upshift Checkball (#8)

Exhausting the 2nd clutch fluid pressure unseats the ball and is routed through the 2nd fluid circuit.

The Lo/1st fluid is regulated through the lo overrun valve and into the Lo/reverse fluid circuit in order to control the lo and reverse clutch apply.

Lo and Reverse Piston

The Lo/reverse fluid pressure acts on the inner area of the piston in order to move the piston and in order to apply the lo and reverse clutch plates.

Overrun Clutch Applied

The overrun clutch remains applied in manual first in order to provide engine compression braking.

Similar to manual second, the PCM output signal to the PC solenoid valve increases the operating range of the torque signal fluid pressure. This provides the increased line pressure for the additional torque requirements during the engine compression braking and the increased engine loads.

3-2 Downshift Control Solenoid Valve and the 3-2 Control Valve

In first gear the solenoid is OFF, the AFL fluid is blocked by the solenoid, and the 3-2 signal fluid exhausts through the solenoid and the spring force opens the 3-2 control valve.

Scheme 241

Reverse

When the gear selector lever is moved to the Reverse (R) position (from the Park position), the following changes occur to the transmissions hydraulic and electrical systems

The manual valve moves to the Reverse position and line pressure enters the reverse fluid circuit. As in Park, line pressure also fills the PR (Park/Reverse) fluid circuit. All other fluid circuits are blocked by the manual valve.

Lo and Reverse Clutch

As in Park, PR fluid pressure acts on the outer area of the lo and reverse clutch piston to apply the lo and reverse clutch. Also, Lo/reverse fluid from the lo overrun valve acts on the inner area of the piston to increase the holding capacity of the clutch (see Note below).

Reverse fluid pressure seats the #3 checkball, flows through orifice #17 and fills the reverse input fluid circuit. This orifice helps control the reverse input clutch apply rate when engine speed is at idle.

Reverse fluid pressure acts on the end of the valve opposite of spring force. At engine speeds above idle, reverse fluid pressure, which is fed by line pressure, increases and moves the valve against spring force (as shown). Reverse fluid can then fill the reverse input fluid circuit through the reverse abuse valve. This bypasses the control of orifice #17 and provides a faster clutch apply.

Reverse input fluid pressure moves the boost valve against the pressure regulator valve spring. The spring acts on the pressure regulator valve to increase the operating range of line pressure in Reverse. Reverse input fluid also flows through the valve and to the reverse input clutch piston. Remember that torque signal fluid pressure continually acts on the boost valve to control line pressure in response to vehicle operating conditions.

Reverse input fluid pressure moves the piston to apply the reverse input clutch plates and obtain Reverse.

Reverse Input Air Bleed Checkball

This ball and capsule is located in the reverse input fluid circuit in the oil pump to provide an air escape when the fluid pressure increases. It also allows air into the circuit to displace the fluid when the clutch releases.

Both shift solenoid valves are energized as in the Park range. Signal A and signal B fluids are blocked from exhausting through the shift solenoid valves to maintain fluid pressure in these circuits at the end of the shift valves.

Signal A fluid pressure holds the 1-2 shift valve in the downshifted position and the 3-4 shift valve in the upshifted (First and Fourth gear) position. Signal B fluid pressure from the 2-3 shift solenoid valve holds the 2-3 shift valve train in the downshifted position.

The PC solenoid valve continues to regulate AFL fluid into torque signal fluid pressure. The PCM varies the current at the solenoid to regulate torque signal fluid pressure in response to throttle position and other PCM input signals. Torque signal fluid pressure is used to control line pressure at the boost and pressure regulator valves.

Note: The explanation in each gear range is, for the most part, limited.

Scheme 242

Scheme 243

Scheme 244

Scheme 245

Scheme 246

Scheme 247

Scheme 248

Scheme 249

Scheme 250

Scheme 251

Scheme 252

Scheme 253

How to Use This Section

This section provides the following information

1. General diagnosis information on transmissions
2. Procedures for diagnosing the Hydra-Matic transmission

When you diagnose any condition of the Hydra-Matic transmission, begin with A Diagnostic Starting Point. This procedure indicates the proper path of diagnosing the transmission by describing the basic checks. This procedure will then refer you to the locations of specific checks. After you have determined the cause of a condition, refer to Repair Instructions for repair procedures. If the faulty component is not serviceable without removing the transmission from the vehicle, refer to Unit Repair for repair information.

Basic Knowledge

Note. Do not, under any circumstances, attempt to diagnose a powertrain condition without basic knowledge of this powertrain. If you perform diagnostic procedures without this basic knowledge, you may incorrectly diagnose the condition or damage the powertrain components.

You must be familiar with some basic electronics in order to use this section of the service manual. You should also be able to use the following special tools

1. A digital multimeter (DMM)
2. A circuit tester
3. Jumper wires or leads
4. A line pressure gauge set

Transmission Adaptive Functions

The 4L60-E transmission utilizes a line pressure control system during upshifts to compensate for the normal wear of transmission components. By adjusting the line pressure, the PCM can maintain acceptable transmission shift times. This process is known as "adaptive learning" or "shift adapts" and is similar to the closed loop fuel control system used for the engine.

In order for the PCM to perform a "shift adapt," it must first identify if an upshift is acceptable to analyze. For example, upshifts that occur during cycling of the A/C compressor or under extreme throttle changes could cause the PCM to incorrectly adjust line pressure. When an upshift is initiated, a number of contingencies, such as throttle position, transmission temperature, and vehicle speed, are checked in order to determine if the actual shift time is valid to compare to a calibrated desired shift time. If all the contingencies are met during the entire shift, then the shift is considered valid and the adapt function may be utilized if necessary.

Once an adaptable shift is identified, the PCM compares the actual shift time to the desired shift time and calculates the difference between them. This difference is known as the shift error. The actual shift time is determined from the time that the PCM commands the shift to the start of the engine RPM drop initiated by the shift. If the actual shift time is longer than the calibrated desired shift time, a soft feel or slow engagement, then the PCM decreases current to the pressure control (PC) solenoid in order to increase line pressure for the next, same, upshift under identical conditions. If the actual shift time is shorter than the calibrated desired shift time, a firm engagement, then the PCM increases current to the PC solenoid in order to decrease line pressure for the next, same, upshift under identical conditions.

The purpose of the adapt function is to automatically compensate the shift quality for the various vehicle shift control systems. It is a continuous process that will help to maintain optimal shift quality throughout the life of the vehicle.

Clearing Transmission Adaptive Pressure (TAP)

Transmission adaptive pressure (TAP) information is displayed and may be reset using a scan tool.

The adapt function is a feature of the PCM that either adds or subtracts line pressure from a calibrated base line pressure in order to compensate for normal transmission wear. The TAP information is divided into 13 units, called cells. The cells are numbered 4 through 16. Each cell represents a given torque range. TAP cell 4 is the lowest adaptable torque range and TAP cell 16 is the highest adaptable torque range. It is normal for TAP cell values to display zero or negative numbers. This indicates that the PCM has adjusted line pressure at or below the calibrated base line pressure.

Updating TAP information is a learning function of the PCM designed to maintain acceptable shift times. It is not recommended that TAP information be reset unless one of the following repairs has been made

1. Transmission overhaul or replacement
2. Repair or replacement of an apply or release component, clutch, band, piston, servo
3. Repair or replacement of a component or assembly which directly affects line pressure

Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the PCM will need to relearn TAP values. Transmission performance may be affected as new TAPs are learned. Learning can only take place when the PCM has determined that an acceptable shift has occurred. The PCM must also relearn TAP values if it is replaced.

Scheme 254

The 1-2 and 2-3 shift solenoid valves (also called A and B solenoids) are identical devices that control the movement of the 1-2 and 2-3 shift valves. The 3-4 shift valve is not directly controlled by a shift solenoid. The solenoids are normally-open exhaust valves that work in 4 combinations to shift the transmission into different gears.

The powertrain control module (PCM) energizes each solenoid by grounding the solenoid through an internal quad driver. This sends current through the coil winding in the solenoid and moves the internal plunger out of the exhaust position. When ON, the solenoid redirects fluid to move a shift valve.

The PCM-controlled shift solenoids eliminate the need for TV and governor pressures to control shift valve operation.

Scheme 255

The 3-2 shift solenoid valve assembly is a normally-closed, 3-port, ON/OFF device that is used in order to improve the 3-2 downshift. The solenoid regulates the release of the 3-4 clutch and the 2-4 band apply.

Scheme 256

The transmission pressure control solenoid is an electronic pressure regulator that controls pressure based on the current flow through its coil winding. The magnetic field produced by the coil moves the solenoid's internal valve which varies pressure to the pressure regulator valve.

The PCM controls the pressure control solenoid by commanding current between 0.1-1.1 amps. This changes the duty cycle of the solenoid, which can range between 5-95 percent, typically less than 60 percent. High amperage (1.1 amps) corresponds to minimum line pressure, and low amperage (0.1 amp) corresponds to maximum line pressure, if the solenoid loses power, the transmission defaults to maximum line pressure.

The PCM commands the line pressure values, using inputs such as engine speed and throttle position sensor voltage.

The pressure control solenoid takes the place of the throttle valve or the vacuum modulator that was used on past model transmissions.

Scheme 257

The torque converter clutch (TCC) solenoid valve is a normally-open exhaust valve that is used to control torque converter clutch apply and release. When grounded (energized) by the powertrain control module (PCM), the TCC solenoid valve stops converter signal oil from exhausting. This causes converter signal oil pressure to increase and move the TCC solenoid valve into the apply position.

Scheme 258

The torque converter clutch pulse width modulation solenoid valve controls the fluid acting on the converter clutch valve. The converter clutch valve controls the torque converter clutch (TCC) apply and release. This solenoid is attached to the control valve body assembly within the transmission. The TCC PWM solenoid valve provides a smooth engagement of the torque converter clutch by operating during a duty cycle percent of ON time.

Scheme 259

The transmission fluid pressure (TFP) manual valve position switch consists of five pressure switches (two normally-closed and three normally-open) on the control valve body that sense whether fluid pressure is present in five different valve body passages. The combination of switches that are open and closed is used by the PCM in order to determine the actual manual valve position. The TFP manual valve position switch, however, cannot distinguish between PARK and NEUTRAL because the monitored valve body pressures are identical in both cases.

The switches are wired to provide three signal lines that are monitored by the PCM. These signals are used to help control line pressure, torque converter clutch apply and shift solenoid valve operation. Voltage at each of the signal lines is either zero or twelve volts.

In order to monitor the TFP manual valve position switch operation, the PCM compares the actual voltage combination of the switches to a TFP combination table stored in its memory.

The TFP manual valve position switch signal voltage can be measured from each pin-to-ground and compared to the combination table. On the automatic transmission (AT) wiring harness assembly, pin N is signal A, pin R is signal B, and pin P is signal C. With the AT wiring harness assembly connected and the engine running, a voltage measurement of these three lines will indicate a high reading (near 12 volts) when a circuit is open, and a low reading (zero volts) when the circuit is switched to ground.

The transmission fluid temperature (TFT) sensor is part of the TFP manual valve position switch assembly.

Scheme 260

The vehicle speed sensor (VSS) assembly provides vehicle speed information to the PCM. The VSS assembly is a permanent magnet (PM) generator. The PM generator produces a pulsing AC voltage as rotor teeth on the transmission output shaft pass through the sensor's magnetic field. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. Output voltage varies with speed from a minimum of 0.5 volts at 100 RPM to more than 100 volts at 8,000 RPM. The PCM converts the pulsing voltage to vehicle speed. The PCM uses the vehicle speed signal to determine shift timing and TCC scheduling.