42RLE Automatic Transmission - Service Information: Overview RAM Pickup 2500

Scheme 337

The 42RLE is a four-speed transmission that is a conventional hydraulic/mechanical assembly controlled with adaptive electronic controls and monitors. (Scheme 337) The hydraulic system of the transmission consists of the transmission fluid, fluid passages, hydraulic valves, and various line pressure control components. An input clutch assembly which houses the underdrive, overdrive, and reverse clutches is used. It also utilizes separate holding clutches: 2nd/4th gear and Low/Reverse. The primary mechanical components of the transmission consist of the following

1. Three multiple disc input clutches
2. Two multiple disc holding clutches
3. Four hydraulic accumulators
4. Two planetary gear sets
5. Hydraulic oil pump
6. Valve body
7. Solenoid/Pressure switch assembly

Control of the transmission is accomplished by fully adaptive electronics. Optimum shift scheduling is accomplished through continuous real-time sensor feedback information provided to the Transmission Control Module (TCM) portion of the Powertrain Control Module (PCM).

The TCM is the heart of the electronic control system and relies on information from various direct and indirect inputs (sensors, switches, etc.) to determine driver demand and vehicle operating conditions. With this information, the TCM can calculate and perform timely and quality shifts through various output or control devices (solenoid pack, transmission control relay, etc.).

The TCM also performs certain self-diagnostic functions and provides comprehensive information (sensor data, DTC's, etc.) which is helpful in proper diagnosis and repair. This information can be viewed with the scan tool.

Scheme 338

The 42RLE transmission can be identified by a barcode label that is affixed to the upper left area of the bellhousing.

The label contains a series of digits that can be translated into useful information such as transmission part number (10), date of manufacture (4, 5), manufacturing origin (2), assembly line identifier (6), build sequence number (7), etc. (Scheme 338)

If the tag is not legible or is missing, the "PK" number, which is stamped into the left rear flange of the transmission case, can be referred to for identification. The entire part number, build code, and sequence number are stamped into the flange.

OPERATION

The 42RLE transmission ratios are

Scheme 339

In first gear range, torque input is through the underdrive clutch (1) to the underdrive hub assembly. (Scheme 339) The underdrive hub is splined to the rear sun gear. When the underdrive clutch is applied, it rotates the underdrive hub and rear sun gear. The L/R clutch (2) is applied to hold the front carrier/rear annulus assembly. The rear sun gear drives the rear planetary pinion gears. The rear planetary pinion gears are forced to walk around the inside of the stationary rear annulus gear. The pinions are pinned to the rear carrier and cause the rear carrier assembly to rotate as they walk around the annulus gear. This provides the torque output for first gear. The other planetary gearset components are freewheeling. The first gear ratio is 2.84:1.

Scheme 340

Second gear is achieved by having both planetary gear sets contribute to torque multiplication. (Scheme 340) As in first gear, torque input is through the underdrive clutch (1) to the rear sun gear. The 2/4 clutch (2) is applied to hold the front sun gear stationary. The rotating rear sun gear turns the rear planetary pinions. The rear pinions rotate the rear annulus/front carrier assembly. The pinions of the front carrier walk around the stationary front sun gear. This transmits torque to the front annulus/rear carrier assembly, which provides output torque and a gear ratio of 1.57:1.

Scheme 341

In third gear, two input clutches are applied to provide torque input: the underdrive clutch (1) and overdrive clutch (2). (Scheme 341) The underdrive clutch rotates the rear sun gear, while the overdrive clutch rotates the front carrier/rear annulus assembly. The result is two components (rear sun gear and rear annulus gear) rotating at the same speed and in the same direction. This effectively locks the entire planetary gearset together and is rotated as one unit. The gear ratio in third is 1:1.

Scheme 342

In fourth gear input torque is through the overdrive clutch (1) which drives the front carrier. (Scheme 342) The 2/4 clutch (2) is applied to hold the front sun gear. As the overdrive clutch rotates the front carrier, it causes the pinions of the front carrier to walk around the stationary front sun gear. This causes the front carrier pinions to turn the front annulus/rear carrier assembly which provides output torque. In fourth gear, transmission output speed is more than engine input speed. This situation is called overdrive and the gear ratio is 0.69:1.

Scheme 343

In reverse, input power is through the reverse clutch (1). (Scheme 343) When applied, the reverse clutch drives the front sun gear through the overdrive hub and shaft. The L/R clutch (2) is applied to hold the front carrier/rear annulus assembly stationary. The front carrier is being held by the L/R clutch so the pinions are forced to rotate the front annulus/rear carrier assembly in the reverse direction. Output torque is provided, in reverse, with a gear ratio of 2.21:1.

42RLE automatic transmission malfunctions may be caused by these general conditions

1. Poor engine performance
2. Improper adjustments
3. Hydraulic malfunctions
4. Mechanical malfunctions
5. Electronic malfunctions

When diagnosing a problem always begin with recording the complaint. The complaint should be defined as specific as possible. Include the following checks

1. Temperature at occurrence (cold, hot, both)
2. Dynamic conditions (acceleration, deceleration, upshift, cornering)
3. Elements in use when condition occurs (what gear is transmission in during condition)
4. Road and weather conditions
5. Any other useful diagnostic information.

After noting all conditions, check the easily accessible variables

1. Fluid level and condition
2. Shift cable adjustment
3. Diagnostic trouble code inspection

Then perform a road test to determine if the problem has been corrected or that more diagnosis is necessary. If the problem exists after the preliminary tests and corrections are completed, hydraulic pressure checks should be performed.

The function of an accumulator is to cushion the application of a frictional clutch element. When pressurized fluid is applied to a clutch circuit, the application force is dampened by fluid collecting in the respective accumulator chamber against the piston and springs. The intended result is a smooth, firm clutch application.

The three input clutches are responsible for driving different components of the planetary geartrain.

Note. for a collective view of which clutch elements are applied at each position of the selector lever. Refer to Diagnosis and Testing .

The planetary geartrain utilizes two planetary gear sets that connect the transmission input shaft to the output shaft. Input and holding clutches drive or lock different planetary members to change output ratio or direction.

Scheme 344

Two hydraulically applied multi-disc clutches are used to hold planetary geartrain components stationary while the input clutches drive others. The 2/4 (2) and Low/Reverse (3) clutches are considered holding clutches and are contained at the rear of the transmission case. see scheme 245

Note. for a collective view of which clutch elements are applied at each position of the selector lever. Refer to Diagnosis and Testing .

The system locks the shifter into the PARK position. The interlock system is engaged whenever the ignition switch is in the LOCK or ACCESSORY position. An additional electrically activated feature will prevent shifting out of the PARK position unless the brake pedal is depressed approximately one-half an inch. A magnetic holding device in line with the park lock cable is energized when the ignition is in the RUN position. When the key is in the RUN position and the brake pedal is depressed, the shifter is unlocked and will move into any position. The interlock system also prevents the ignition switch from being turned to the LOCK or ACCESSORY position, unless the shifter is fully locked into the PARK position.

As the torque converter rotates, the converter hub rotates the inner and outer gears. As the gears rotate, the clearance between the gear teeth increases in the crescent area, and creates a suction at the inlet side of the pump. This suction draws fluid through the pump inlet from the oil pan. As the clearance between the gear teeth in the crescent area decreases, it forces pressurized fluid into the pump outlet and to the valve body.

Scheme 345

Scheme 346

1. Remove the reaction shaft support bolts.
2. Remove the reaction shaft support (2) from the pump housing (1). 1 - PUMP HOUSING 2 - OUTER PUMP GEAR 3 - INNER PUMP GEAR 4 - REACTION SHAFT SUPPORT 5 - SEAL RINGS (4) 6 - REACTION SHAFT 7 - CRESCENT
3. Remove the pump gears (2, 3) and check for wear and damage on pump housing (1) and gears (2, 3).

DESCRIPTION

Note. Due to different power control configurations, the Transmission Control Relay (if equipped) may be referred to as a PCM relay.

The relay is supplied fused B+ voltage, energized by the TCM, and is used to supply power to the solenoid pack when the transmission is in normal operating mode.

Note. Due to different power control configurations, the Transmission Control Relay (if equipped) may be referred to as a PCM relay.

When the relay is "off", no power is supplied to the solenoid pack and the transmission is in "limp-in" mode. After a controller reset, the TCM energizes the relay. Prior to this, the TCM verifies that the contacts are open by checking for no voltage at the switched battery terminals. After this is verified, the voltage at the solenoid pack pressure switches is checked. After the relay is energized, the TCM monitors the terminals to verify that the voltage is greater than 3 volts.

Scheme 347

1. Raise vehicle.
2. Mark propeller shaft and axle yoke, or companion flange, for alignment reference.
3. Disconnect and remove propeller shaft.
4. Remove old seal with a generic seal remover (1) from overdrive extension housing. see scheme 254

Scheme 348

1. Place seal in position on overdrive housing.
2. Drive seal into overdrive housing with Seal Installer (special tool #C-3995-A, Installer, Seal) (1). see scheme 255
3. Carefully guide propeller shaft slip yoke into housing and onto output shaft splines. Align marks made at removal and connect propeller shaft to rear axle pinion yoke.

The Input (1) and Output (2) Speed Sensors are two-wire magnetic pickup devices that generate AC signals as rotation occurs. see scheme 256 They are mounted in the left side of the transmission case and are considered primary inputs to the Transmission Control Module (TCM).

The Input Speed Sensor provides information on how fast the input shaft is rotating. As the teeth of the input clutch hub pass by the sensor coil, an AC voltage is generated and sent to the TCM. The TCM interprets this information as input shaft RPM.

The Output Speed Sensor generates an AC signal in a similar fashion, though its coil is excited by rotation of the rear planetary carrier lugs. The TCM interprets this information as output shaft RPM.

The TCM compares the input and output speed signals to determine the following

1. Transmission gear ratio
2. Speed ratio error detection
3. CVI calculation

The TCM also compares the input speed signal and the engine speed signal to determine the following

1. Torque converter clutch slippage
2. Torque converter element speed ratio

The Input (1) and Output (2) Speed Sensors are two-wire magnetic pickup devices that generate AC signals as rotation occurs. see scheme 259 They are mounted in the left side of the transmission case and are considered primary inputs to the Transmission Control Module (TCM).

The Input Speed Sensor provides information on how fast the input shaft is rotating. As the teeth of the input clutch hub pass by the sensor coil, an AC voltage is generated and sent to the TCM. The TCM interprets this information as input shaft RPM.

The Output Speed Sensor generates an AC signal in a similar fashion, though its coil is excited by rotation of the rear planetary carrier lugs. The TCM interprets this information as output shaft RPM.

The TCM compares the input and output speed signals to determine the following

1. Transmission gear ratio
2. Speed ratio error detection
3. CVI calculation

The TCM also compares the input speed signal and the engine speed signal to determine the following

1. Torque converter clutch slippage
2. Torque converter element speed ratio

The transmission range sensor (TRS) has an integrated thermistor that the TCM uses to monitor the transmission's sump temperature. Since fluid temperature can affect transmission shift quality and convertor lock up, the TCM requires this information to determine which shift schedule to operate in. The TCM also monitors this temperature data so it can energize the vehicle cooling fan(s) when a transmission "overheat" condition exists. If the thermistor circuit fails, the TCM will revert to calculated oil temperature usage.

The Transmission Range Sensor (TRS) (2) is mounted to the top of the valve body inside the transmission and can only be serviced by removing the valve body assembly. (Scheme 346) The electrical connector extends through the transmission case.

The Transmission Range Sensor (TRS) has four switch contacts that monitor shift lever position and send the information to the PCM.

The Transmission Range Sensor (TRS) communicates shift lever position (SLP) to the TCM as a combination of open and closed switches. Each shift lever position has an assigned combination of switch states (open/closed) that the TCM receives from four sense circuits. The TCM interprets this information and determines the appropriate transmission gear position and shift schedule.

Since there are four switches, there are 16 possible combinations of open and closed switches (codes). Seven of these codes are related to gear position and three are recognized as "between gear" codes. This results in six codes which should never occur. These are called "invalid" codes. An invalid code will result in a DTC, and the TCM will then determine the shift lever position based on pressure switch data. This allows reasonably normal transmission operation with a TRS failure.

TRS SWITCH STATES

Scheme 349

Scheme 350

1. Remove valve body assembly from vehicle. Refer to «VALVE BODY, Removal»(ref-457852-S17701709272012030200000).
2. Remove the manual shaft seal (1). see scheme 264 1 - SCREW 2 - TRS
3. Remove manual shaft/TRS retaining screw (1). see scheme 265
4. Slide TRS off of manual valve shaft.

The TCM calculates the desired line pressure based upon inputs from the transmission and engine. The TCM calculates the torque input to the transmission and uses that information as the primary input to the calculation. The line pressure is set to a predetermined value during shifts and when the transmission is in the PARK and NEUTRAL positions. This is done to ensure consistent shift quality. During all other operation, the actual line pressure is compared to the desired line pressure and adjustments are made to the pressure control solenoid duty cycle.

The gear shift mechanism provides six shift positions which are

1. Park (P)
2. Reverse (R)
3. Neutral (N)
4. Drive (D)
5. Manual second (2)
6. Manual low (1)

MANUAL LOW (1) range provides FIRST gear only. Overrun braking is also provided in this range. MANUAL SECOND (2) range provides FIRST and SECOND gear only.

DRIVE range provides FIRST, SECOND, THIRD and OVERDRIVE FOURTH gear ranges. The shift into OVERDRIVE FOURTH gear range occurs only after the transmission has completed the shift into D THIRD gear range. No further movement of the shift mechanism is required to complete the 3-4 shift.

The FOURTH gear upshift occurs automatically when the overdrive selector switch is in the ON position. An upshift to FOURTH gear may not occur or may be delayed in some of the possible shift schedules. Refer to MODULE, Transmission Control , Operation .

Scheme 351

Scheme 352

Scheme 353

Scheme 354

Scheme 355

Scheme 356

Scheme 357

Scheme 358

1. Using trim stick (special tool #C-4755, Trim Stick) or equivalent, remove the console bezel trim ring (1).
2. Remove the rubber insert (1) from the console bezel.
3. Remove the fasteners (1) at the front of the console bezel.
4. Using trim stick (special tool #C-4755, Trim Stick) or equivalent, remove console bezel (1).
5. Remove the rubber liners from the center storage tray and cupholders in the console PRNDL bezel, and remove the fasteners (1).
6. Disconnect the power outlet harness connector (1) and the shifter harness connector (2).
7. Place the shifter in park.
8. Remove the fasteners (1), and position the shifter assembly (2) so the cable end is accessible.
9. Disconnect the shift cable retainer (2) from the bracket.
10. Disconnect the shifter cable end (1) from the shifter lever.
11. Remove the shifter assembly.

Scheme 359

Scheme 360

Scheme 361

1. Using trim stick (special tool #C-4755, Trim Stick) or equivalent, remove the console bezel trim ring (1).
2. Remove the rubber insert (1) from the console bezel.
3. Remove the fasteners (1) at the front of the console bezel.
4. Using trim stick (special tool #C-4755, Trim Stick) or equivalent, remove the console bezel (1).
5. Remove the rubber liners from the center storage tray and cupholders in the console PRDL bezel, and remove the fasteners (1).
6. Disconnect the power outlet harness connector (1) and the shifter harness connector (2).
7. Twist the lower trim piece (1) on the base of the shifter knob counterclockwise, then push down to disengage the trim piece (1).
8. Remove the shifter knob.
9. Twist the shift position indicator lamp connector (1) 1/4 turn counterclockwise, then disconnect the lamp from the console PRNDL bezel.
10. Release the clips (1) on the console PRNDL bezel, and remove the console PRNDL bezel.

The pressure control solenoid (1) is mounted on the top of the valve body, next to the line pressure sensor (2). see scheme 305

The TCM utilizes a closed-loop system to control transmission line pressure. The system contains a variable force style solenoid, the Pressure Control Solenoid. The solenoid is duty cycle controlled by the TCM to vent the unnecessary line pressure supplied by the oil pump back to the sump. The system also contains a variable pressure style sensor, the Line Pressure Sensor, which is a direct input to the TCM. The line pressure solenoid monitors the transmission line pressure and completes the feedback loop to the TCM. The TCM uses this information to adjust its control of the pressure control solenoid to achieve the desired line pressure.

The pressure control solenoid (PCS) is a variable force (VFS) style solenoid. A VFS solenoid is an electro-hydraulic actuator, combining a solenoid and a regulating valve.

The transmission control module varies the current for the PCS, which varies the pressure in the line pressure hydraulic circuit. When the current (duty cycle) of the PCS is low, the pressure in the circuit is higher. At 0 current (0% duty cycle), the pressure is at the maximum value. Conversely, when the current is maximized (100% duty cycle), the pressure in the circuit is at the lowest possible value.

At key-on, overdrive operation is allowed. Pressing the switch once enables Tow/Haul mode and the Tow/Haul lamp will be illuminated. In Tow/Haul mode, 5th gear is disabled and 3-4 upshifts are delayed. Shifts into 4th gear are still allowed under steady cruise conditions. Closed throttle downshifts (for improved engine braking) may occur during steady braking maneuvers. Pressing the switch a second time enables OD Off mode, where all 4th and 5th gear operation is inhibited. Pressing the switch a third time restores normal operation. Normal operation is always the default at start-up; the switch must be pressed after each key start if Tow/Haul mode is desired.

Scheme 362

Scheme 363

1. Using a plastic trim tool, remove the tow/haul overdrive off switch retainer (2) from the shift lever (1). 1 - GEAR SHIFT LEVER 2 - SWITCH
2. Pull the switch (2) outwards to release it from the connector in the lever (1).

The converter impeller (driving member), which is integral to the converter housing and bolted to the engine drive plate, rotates at engine speed. see scheme 318 The converter turbine (driven member), which reacts from fluid pressure generated by the impeller, rotates and turns the transmission input shaft.

Scheme 364

The valve body assembly consists of a cast aluminum valve body (5), separator plate (4), and transfer plate (3). see scheme 321 The valve body contains valves and check balls that control fluid delivery to the torque converter clutch, solenoid/pressure switch assembly, and frictional clutches.

Also mounted to the valve body assembly are the solenoid/pressure switch assembly and the transmission range sensor (2). see scheme 321

Scheme 365

The valves contained within the valve body (1) include the following

1. Regulator valve (8)
2. Solenoid switch valve (7)
3. Manual valve (5)
4. Converter clutch switch valve (6)
5. Converter clutch control valve (4)
6. Torque converter regulator valve (2)
7. Low/Reverse switch valve (3)

In addition, the valve body also contains the thermal valve, #2, 3, 4 AND 5 check balls and the 2/4 accumulator assembly.

Note. for a visual aid in determining valve location, operation and design. Refer to Schematics and Diagrams .

Scheme 366

The thermal valve (1) is a bi-metallic shudder valve that helps control the venting rate of oil pressure in the underdrive clutch passage during release of the clutch. (Scheme 363) When the oil temperature is approximately 20 degrees Fahrenheit or less, the valve is fully open to assist in venting oil past the U1 orifice (2). At temperatures above 20 degrees, the valve starts to close and becomes fully closed at approximately 140 degrees. The thermal valve is located in the transfer plate of the valve body.

Scheme 367

The regulator valve (9) controls hydraulic pressure in the transmission. see scheme 324 It receives unregulated pressure from the pump (6), which works against spring tension (8) to maintain oil at specific pressures. A system of sleeves and ports allows the regulator valve to work at one of three predetermined pressure levels. Regulated oil pressure is also referred to as "line pressure".

Scheme 368

The solenoid switch valve controls line pressure from the LR/CC solenoid (4). see scheme 325 In one position, it allows the low/reverse clutch to be pressurized. In the other, it directs line pressure to the converter control and converter clutch valves (7).

Scheme 369

The manual valve (4) is operated by the mechanical shift linkage. see scheme 326 Its primary responsibility is to send line pressure to the appropriate hydraulic circuits and solenoids. The valve has three operating ranges or positions.

Scheme 370

The main responsibility of the converter clutch switch valve (10) is to control hydraulic pressure applied to the front (off) side of the converter clutch piston. see scheme 327 Line pressure from the regulator valve (5) is fed to the torque converter regulator valve (8). The pressure is then directed to the converter clutch switch valve (10) and to the front side of the converter clutch piston. This pressure pushes the piston back and disengages the converter clutch.

Scheme 371

The converter clutch control valve (5) controls the back (on) side of the torque converter clutch (1). see scheme 328 When the controller energizes or modulates the LR/CC solenoid to apply the converter clutch piston, both the converter clutch control valve (5) and the converter control valve move, allowing pressure to be applied to the back side of the clutch.