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This page last updated: March 23, 2008

WK transmissions

High-Performance Five-Speed Automatic Transmissions

4.7L V8 engine

Two different transmissions are offered for the 2005-2010 Grand Cherokee models. An all-new W5A580 five-speed automatic transmission offers smooth shifts and optimum fuel economy with the 3.7-liter V-6. The 545RFE five-speed automatic has been refined for higher-quality shifts while increasing the Grand Cherokee’s maximum towing capacity. The all-new five-speed has an Electronically Modulated Converter Clutch (EMCC). The torque converter clutch is electronically modulated and provides for partial engagement in third, fourth or fifth gears. This results in improved shift feel, fuel economy, driveability and transmission cooling. It can be used at lower speeds to provide benefits over a broad speed range. The system unlocks the torque converter when optimal performance is required.

The 545RFE five-speed transmission has been refined to offer smoother operation and better economy while improving the performance and towing capability of the vehicle.

Both transmissions feature Electronic Range Select (ERS) driver interactive shift control for the first time on a Grand Cherokee. The shifter provides fully-automated shifting when in the “drive” position, or the driver can manually select each gear by simply moving the shifter left and right from the “drive” position. This gives the driver control to precisely match any on-road or off-road driving requirement.

W5A580 transmission features
(Standard on Laredo, N/A on Limited or Overland, Standard on SRT8)

The W5A580 debuted in 1995 Mercedes-Benz passenger vehicles and is known to be one of the smoothest, most fuel-efficient and cost-effective transmissions in the industry. Its unique three-channel torque converter helps provide an exceptionally smooth ride and shifting, while reducing fuel consumption. A $455 million upgrade project at the Indiana Transmission Plant was started in 2001 and completed in 2003. The 600,000 SF plant was designed to produce around 400,000 of the W5A580 transmissions per year for the North American market. The transmission project was the first joint effort between the company's American and German wings after the Chrysler Corp. and Daimler-Benz merge in 1998.

A broad ratio spread from First to the Fifth was selected to minimize fuel consumption and reduce powertrain noise during cruising. An aggressive First-gear ratio provides excellent launch performance, and evenly spaced gear ratios provide smooth acceleration through the gears.

World-class efficiency is achieved through physical and electronic means. This transmission uses bearings to reduce friction in many locations where other transmissions may utilize bushings. The transmission also uses a unique scavenging system that removes oil spun off of the rotating parts by centrifugal force through strategically placed slots in the outside of the case. This saves energy that would be consumed by internal parts rotating in oil. Lubricating holes in the clutches are also positioned to promote quick passage of the transmission fluid through the discs, minimizing viscous losses due to trapped oil.

The shift schedule adapts to individual driving style, driving situation and road conditions, altering shift points based on an accelerator pedal usage, brake usage, lateral acceleration, altitude and load on the car as a result of grades. Electronically controlled engine torque management provides quick wide-open-throttle up shifts and quick two-step (4-2 or 3-1) kick-down shifts that are exceptionally smooth.

Transmission ratios:

Gear W5A580545RFE
1st3.59 3.00
2nd2.191.67 upshift / 1.50 kickdown

Fully adaptive electronic control of all shifting makes shifts very smooth. The system monitors the transmission as shifts occur and adjusts hydraulic pressure as needed. In so doing, the controls make the powertrain feel responsive without harshness.

Driver recognition software alters shift points based on accelerator pedal usage, brake usage and lateral acceleration. This does not require a compromise between sporty and economical operation, nor is it a question of choosing one or the other.

A torque management system uses engine torque modeling to facilitate smooth transmission shifting. Because of electronic throttle control, torque management is more sophisticated and covers a broad torque range.

Torque converter clutch slippage is electronically modulated and provides for partial engagement in Third, Fourth or Fifth gears. This results in improved shift feel, fuel economy, driveability and cooling. It can be used at lower speeds to provide benefits over a broad speed range. The system disengages as required to provide optimal performance.

545RFE transmission features
(Standard on Limited and Overland, N/A on Laredo or SRT8)

The 545RFE five-speed transmission has been refined to offer smoother operation and better economy while improving the performance and towing capability of the vehicle. To accomplish all this, several features were added, including a redesigned solenoid to provide quieter operation when shifting from "park" into "drive." A turbine damper also improves NVH, related to torque converter application.

The 545RFE continues to offer dual second-gear ratios to provide a balance of performance and fuel economy. Depending on driving conditions, the transmission will select the more appropriate second gear. A secondary overdrive ratio increases highway fuel economy and reduces engine noise at high speeds.

Transmission ratios:

Gear W5A580545RFE
1st3.59 3.00
2nd2.191.67 upshift / 1.50 kickdown

Gear Ranges

NOTE: After selecting any gear range, wait a moment to allow the selected gear to engage before accelerating. This is especially important when the engine is cold. If there is a need to restart the engine be sure to cycle the key to the LOCK position before restarting. Transmission gear engagement may be delayed after restarting the engine if the key is not cycled to the LOCK position first.

P (Park)
Supplements the parking brake by locking the transmission. The engine can be started in this range. Never use P (Park) while the vehicle is in motion. Apply the parking brake when leaving the vehicle in this range.

R (Reverse)
Shift into this range only after the vehicle has come to a complete stop.

N (Neutral)
No power is transmitted from the engine to the drive axle. When the brakes are released, the vehicle can roll freely. Do not engage in N (Neutral) position while driving except to coast when the vehicle is in danger of skidding (e.g., on icy roads).

NOTE: Towing the vehicle, coasting, or driving for any other reason with selector lever in N (Neutral) can result in severe transmission damage. Refer to “Recreational Towing” in Section 5 and “Towing a Disabled Vehicle” in Section 6 of your owner's manual.

D (Drive)
The transmission automatically upshifts through fifth gear. The D (Drive) position provides optimum driving characteristics under all normal operating conditions.

Electronic Range Select (ERS) Operation

The Electronic Range Select (ERS) shift control allows you to move the shifter left (-) or right (+) when the shifter is in the D (Drive) position, allowing the selection of the desired top gear. For example, if the driver shifts the transmission into 3 (third gear), the transmission will never shift above third gear, but can shift down to 2 (second) or 1 (first), when needed.

NOTE: To select the proper gear position for maximum deceleration (engine braking), move the shift lever to the left “D(-)” and hold it there. The transmission will shift to the range from which the vehicle can best be slowed down.

Screen display 1 2 3 4 D
Actual gear(s) allowed 1 1-2 1-3 1-4 1-5


The overdrive automatic transmission contains an electronically controlled fourth and fifth speed (Overdrive). On prior generation models, the Overdrive "On/Off" button was mounted to the front side of the shifter. For 2005, the button is on the center instrument panel switch array and is labeled as "Tow/Haul". The transmission will automatically shift from 3rd gear to Overdrive if the following conditions are present:

  • The transmission selector is in D (Drive)
  • The engine coolant has reached normal operating temperature
  • Vehicle speed is above approximately 30 mph (48 km/h)
  • The "Tow / Haul" button has not been activated
  • Transmission has reached normal operating temperature

NOTE: If the vehicle is started in extremely cold temperatures, the transmission may not shift into Overdrive and will automatically select the most desirable gear for operation at this temperature. Normal operation will resume when the transmission fluid temperature has risen to a suitable level.

If the transmission temperature gets extremely hot, the transmission will automatically select the most desirable gear for operation at this temperature. If the transmission temperature becomes hot enough, the "TRANSMISSION OVERTEMP" message may display and the transmission may downshift out of Overdrive until the transmission cools down. After cooldown, the transmission will resume normal operation.

In high ambient temperatures with sustained high engine speed and load, an upshift followed shortly thereafter by a downshift may occur. This is a normal part of the overheat protection strategy when operating in the "Tow / Haul" mode. The transmission will downshift from Overdrive to the most desireable gear if the accelerator pedal is fully depressed at vehicle speeds above approximately 35 mph (56 km/h).

When To Use Tow/Haul Mode (all models except SRT8)

When driving in hilly areas, towing a trailer, carrying a heavy load, etc., and frequent transmission shifting occurs, press the "Tow / Haul" button. This will improve performance and reduce the potential for transmission overheating or failure due to excessive shifting. When operating in "Tow / Haul" mode, the transmission will shift to 3rd gear and 4th will be enabled under steady cruise conditions.

The "Tow / Haul" light will illuminate in the instrument cluster to indicate when the switch has been activated. Pressing the switch a second time restores normal operation. If the "Tow / Haul" mode is desired, the switch must be pressed each time the engine is started.

Torque Converter Clutch

A feature designed to improve fuel economy is included in all automatic transmissions. A clutch within the torque converter engages automatically at a calibrated speed at light throttle. It engages at higher speeds under heavier acceleration. This may result in a slightly different feeling or response during normal operation in high gear. When the vehicle speed drops below a calibrated speed, or during acceleration, the clutch automatically and smoothly disengages. The feature is operational in Overdrive and in Drive.

NOTE: The torque converter clutch will not engage until the transmission fluid and engine coolant are warm [usually after 1-3 miles (1.6 - 4.8 km) of driving]. Because the engine speed is higher when the torque converter clutch is not engaged, it may seem as if the transmission is not shifting into Overdrive when cold. This is normal. Pressing the"Tow / Haul" button, when the transmission is sufficiently warm, will demonstrate that the transmission is able to shift into and out of Overdrive.

NOTE: If the vehicle has not been driven in several days, the first few seconds of operation after shifting the transmission into gear may seem sluggish. This is due to the fluid partially draining from the torque converter into the transmission. This condition is normal and will not cause damage to the transmission. The torque converter will refill within five seconds of shifting from Park into any other gear position.

Rocking the Vehicle

If the vehicle becomes stuck in snow, sand, or mud, it can often be moved by a rocking motion. Move the gear selector rhythmically between D (Drive) and R (Reverse), while applying slight pressure to the accelerator.

NOTE: The Electronic Stability Program (ESP) and Traction Control (if equipped) should be turned OFF before attempting to rock the vehicle. The least amount of accelerator pedal pressure to maintain the rocking motion without spinning the wheels or racing the engine is most effective. Racing the engine or spinning the wheels, due to the frustration of not freeing the vehicle, may lead to transmission overheating and failure. Allow the engine to idle with the transmission selector in N (Neutral) for at least one minute after every five rocking-motion cycles. This will minimize overheating and reduce the risk of transmission failure during prolonged efforts to free a stuck vehicle.

CAUTION! When "rocking" a stuck vehicle by moving between "First" and R (Reverse), do not spin the wheels faster than 15 mph (24 km/h), or drivetrain damage may result.


Autostick is a driver-interactive transmission that offers manual gear shifting capability to provide the driver with more control. Autostick allows the driver to increase engine braking ability, control upshift and downshift points, and enhance the driving experience. This system can also provide the driver with more control during passing, city driving, mountain driving, trailer towing, and many other situations.

Autostick Operation

By placing the shift lever in the D (Drive) position the lever can be moved from side to side. This allows the driver to engage the AutoStick mode. Moving the shift lever to the right (+) or the left (-) will engage the Autostick mode. In normal driving mode (Boxed “D” displayed in the PRNDL), moving the shift lever to the right (+) will engage the Autostick mode putting the transmission in the currently engaged gear. Moving the shift lever to the Left (-) will engage the Autostick mode and downshift the transmission 1 gear. For example, the transmission is in Normal Mode and is currently operating in 3rd gear, a boxed D is displayed in the PRNDL, a push to the right will engage the Autostick mode in 3rd and a Boxed 3 will be displayed in the PRNDL. A push to the left (-) will engage Autostick mode and downshift to 2nd gear and a Boxed 2 will be displayed in the PRNDL. Once Autostick mode is engaged a move to the Right (+) or left (-) will trigger a upshift (+) or trigger a downshift (-).

NOTE: In the Autostick mode, the transmission will only shift up and down when Left or Right (D-/D+) is manually selected by the driver.

The transmission will not honor a downshift command if the downshift would result in a engine overspeed condition. The transmission will always honor a upshift command from 1st to 2nd gear, however 2nd - 3rd, 3rd - 4th, and 4th – 5th upshift commands will not be honored if the vehicle speed is to low to maintain operation in the commanded gear. The transmission will automatically downshift as the vehicle slows to a stop.

When in the Autostick mode, as the engine RPM nears the engine maximum speed, an “UPSHIFT” message will appear in the Electronic Vehicle Information Center (EVIC) portion of your instrument cluster. This message appears in order to alert the driver that the engine speed is approaching it’s maximum value and a upshift to the next gear is required. In the event that the driver does notupshift, the engine control system will limit the engine speed to protect the engine.

Shifting into or out of the Autostick mode can be done at any time without taking your foot off the accelerator pedal. When the driver wishes to engage Autostick, simply move the shift lever to the Left or Right (D-/D+) position while in D (Drive).

Hold the shift lever to the right for at least one second to disengage Autostick. The transmission will now operate automatically; shifting between the five available gears.

Autostick General Information

  • You can start out in first or second gear. The system will ignore attempts to upshift at too low of a vehicle speed. The transmission will automatically downshift to first gear when coming to a stop.
  • Starting out in second gear is helpful in snowy or icy conditions.
  • Avoid using speed control when Autostick is engaged.
  • The transmission will not automatically shift up when maximum engine speed is reached while Autostick is engaged.
  • Transmission shifting will be more noticeable when Autostick is engaged.


Shift by wire

Shift-by-wire technology will eliminate the shift lever on future transmissions.

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