Chrysler RFE transmission

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The RFE is an automatic transmission family from Chrysler. The name refers to its Rear wheel drive design and Full Electronic control system.

45RFE and 545RFE

The 45RFE was introduced in the Jeep Grand Cherokee in 1999, it is notable for including 3 planetary gearsets rather than the two normally used in a 4-speed automatic. It also features 3 multiple disc input clutches, 3 multiple disc holding clutches, and a dual internal filter system (one primary filter for transmission sump, one for the fluid cooler return system). In the 45RFE applications four gears are utilized, with a different (1.50:1 rather than 1.67:1) second gear to increase versatility when downshifting. In 545RFE usage, an extra taller overdrive ratio is also used. Chrysler decided to refer to it as a "multi-speed automatic".

The 45RFE is produced at the Indiana Transmission plant in Kokomo, Indiana. It is normally paired with the 4.7 L PowerTech V8.

The 45RFE later became the 5-speed 545RFE. 45RFE transmissions can have their programming changed to enable the 5th forward gear.

  • Gear Ratios:
    • 1st 3.00:1
    • 2nd 1.67:1
    • 2nd Prime 1.50:1
    • 3rd 1.00:1
    • 4th 0.75:1
    • Reverse 3.00:1
  • 545RFE only:
    • 5th 0.67:1



The 68RFE was introduced in 2007 Ram 2500 and 3500 Pickups with the 6.7L Cummins ISB Diesel engine. It is not currently used in 2007-present Ram 3500/4500/5500 cab chassis. Transmission in these models is the Aisin AS68RC. The basic design and operation is the same or similar to the 45 and 545RFE counterparts with the following exceptions:

  • Larger bellhousing different bolt pattern and cutout to accommodate diesel engine.
  • Modified internal components to handle increased torque of diesel engine
  • Revised gear ratios and Transmission Controller programing for larger application
  • There is no 2nd gear prime for downshifting like the 45 and 545RFE transmissions.
  • Gear Ratios:
    • 1st 3.23:1
    • 2nd 1.83:1
    • 3rd 1.41:1
    • 4th 1.00:1
    • 5th 0.81:1
    • 6th 0.62:1
    • Reverse 4.44:1


Basic RFE operation

The fully electronic control is accomplished by the Transmission Control Module (TCM). Depending on year and application, it can either be a stand-alone module or integrated with the Powertrain Control Module (PCM). The TCM uses data from various transmission and engine sensors to control transmission shifting. The transmission operates the solenoid pack to change hydralic flow through the valve body to various clutches in the transmission. The solenoid pack is mounted directly to the valve body, its connector protrudes from a hole on the left side of the transmission. On the 45 and 545RFE the hydraulic control system design (without electronic assist) provides the transmission with PARK, REVERSE, NEUTRAL, SECOND, and THIRD gears, based solely on driver shift lever selection. This design allows the vehicle to be driven (in “limp-in” mode) in the event of a electronic control system failure, or a situation that the Transmission Control Module (TCM) recognizes as potentially damaging to the transmission. On the 68RFE, FOURTH gear is used for limp-in instead of SECOND and THIRD.


See also