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545RFE Automatic Transmission

Jeep's 545RFE Automatic TransmissionThe introduction of the completely redesigned 1999 WJ Grand Cherokee in June of 1998 was a much anticipated date for automotive enthusiasts. One of the major pieces of the redesign was the new five speed automatic transmission designated the 545RFE. This transmission was developed specifically with Jeeps in mind.

This transmission was available only on WJs with a 4.7L V8 engine; the 6 cylinder engine received the venerable 42RE. By design, the 545RFE is quite sophisticated. It employs multiple gear ranges controlled electronically to provide greater fuel economy as well as great responsiveness for passing and acceleration. Precision engineering and manufacturing methods also helped to reduce overall NVH (noise, vibration, harshness). It features five forward gear ratios with an alternative second gear ratio (2 Prime) for smoother 4th to 2nd kickdowns at high speeds to provide spectacular passing performance over a wider speed range. The addition of the fifth (overdrive) gear ratio is the primary cause of the lower NVH and better fuel economy (lower RPMs = less noise and fuel consumption).

It is electronically controlled by the TCM or Transmission Control Module. This module is the heart adaptive shifting programming. The TCM depends on data from several sensors and switches to determine driver demand and the Jeep's operating conditions. Controls are in place to protect the transmission from damage from high temperatures. The TCM protects the transmission by modifying shift schedules, line pressure and converter clutch control. These controls reduce the amount of heat that is created and increase cooling of the 545RFE. The 545RFE is contained by a one-piece die-cast aluminum case. To reduce NVH, integrated into the case are ribs to increase multi-angular torsional rigidity. There are dual lubricant filters in the 545RFE. First is the customary internal main sump pan filter; second is the external canister-type pump return filter.

545RFE Maintenance Recommendations

Fluid Capacity for Service fill (drop pan, change filters, refill): 6.2 Liters or 6.55 Quarts

Fluid Type: Mopar ATF +4, or any Dexron IV approved fluid (author uses Redline Oil Synthetic D4 ATF)

Torque specifications:

Gear Ratio
1st 3.00 : 1
2nd 1.67 : 1
2nd Prime 1.50 : 1
3rd 1.00 : 1
4th 0.75 : 1
5th 0.67 : 1
Reverse 3.00 : 1
Torque Converter Up to 2.40 : 1

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Page created on 10/7/2004
Last updated on 10/7/2004