45RFE Identification Guide: Tag, Connector, Check Balls and Year

Half the 45RFE problems that come across my bench are not transmission problems at all. They are ordering problems. Someone bought a solenoid pack that would not plug in, a valve body with the wrong number of check balls, or a filter kit for a two-wheel-drive truck when the one on the lift has a transfer case bolted to it. Every one of those mistakes starts the same way: somebody identified the transmission by the name on the listing instead of by the parts in front of them.

This guide is the order I actually check things in when a 45RFE, or something that might be a 45RFE, rolls in. It starts with the stamping Chrysler put on the case, rules out the other automatics that share the same trucks, separates the 45RFE and 545RFE from the 68RFE, and then nails down the year generation, which is what the parts catalog really cares about. The service data comes from Chrysler's own 45RFE/545RFE service information, and the identification details come from Sonnax, Transmission Digest and Gears Magazine. Sources are listed at the bottom.

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What the Name Actually Tells You

RFE stands for rear-wheel drive, fully electronic. Per Sonnax's history of the family, Chrysler introduced the RFE in 1999 in the Jeep lineup as its first rear-drive automatic where every shift is commanded by the computer through solenoids. The first version was a four-speed with a torque rating of 5, which is where the name 45RFE comes from. The later 545RFE, 65RFE, 66RFE and 68RFE came out of running updates to the solenoids, gear sets and drums that raised torque and shift ratings (Sonnax, Identifying Chrysler RFE Solenoid Changes).

That is useful, but it is also where people get fooled. The name on the tag tells you what the transmission was calibrated to be. It does not tell you which solenoid pack, valve body or separator plate is inside it. For that you need the year generation, and the year generation is something you confirm with your eyes, not with a model name.

Step 1: Read the Stamping and the Label on the Case

Chrysler's service information is specific about where to look. The transmission identification numbers are stamped on the left side of the case, just above the oil pan sealing surface, and a label is attached to the case above the stamped numbers. Chrysler tells technicians to refer to this information when ordering replacement parts and notes that the label carries additional information that may be needed for identification (Chrysler 45RFE/545RFE service information, Description).

In the real world that area is packed with road film and old ATF, so plan on cleaning it. Spray a rag with brake cleaner rather than spraying the case directly, wipe the pan rail area on the driver side, and read it with a flashlight held low and to the side so the shallow stamping throws a shadow. Take a picture of both the stamping and the label before you do anything else. Labels peel, burn and get pressure-washed off; the stamping survives. On a core that came in without a vehicle attached, that stamping is the only reliable link back to the application.

Step 2: Make Sure It Is an RFE at All

The trucks and SUVs that got a 45RFE also got other automatics, sometimes in the same model year. Chrysler's 2008 Ram fluid capacity sheet lists four different automatics for that one truck line: the 48RE four-speed, the 68RFE, the 45RFE and 545RFE, and an Aisin six-speed (Ram Body Builder 2008 fluid capacities). If a customer says "it's the Ram automatic," that covers a lot of ground.

The quickest way to separate an RFE from the older RE family is how it shifts. Sonnax points out that Chrysler's earlier rear-drive units relied on hydraulic 1-2, 2-3 and 3-4 shift valves and a governor to control gear selection and shift timing, with solenoids handling governor pressure, the converter clutch and the 3-4 shift. The RFE put every shift under solenoid control (Sonnax). On the case, that shows up as the 23-pin pass-through connector for the solenoid and pressure switch assembly, the pin-out of which Sonnax publishes (Sonnax 318).

The RFE case also carries a line pressure sensor, and Chrysler notes it has only two external pressure ports: torque converter clutch apply and release on the right side of the case. Every other pressure tap on this unit is on the valve body and requires the pan off and adapter 8258-A installed (Chrysler hydraulic pressure test). Chrysler also describes the RFE as using dual filters, a main sump filter plus a cooler return filter, which is a detail you will not find on a 46RE or 47RE (Chrysler 545RFE Operation).

One more trap: on 2005-and-later Jeep platforms, Chrysler's service information for the same vehicle covers both the 545RFE and the Mercedes-derived NAG1 five-speed. They share nothing internally. If the vehicle is a Grand Cherokee or Commander, confirm which one it has before a single part gets ordered.

Step 3: 45RFE or 545RFE Versus 68RFE

From underneath, you can rarely tell a 45RFE from a 545RFE. Chrysler lists the same gear train for the family: 3.00 first, 1.67 second, a 1.50 alternate second, 1.00 third, 0.75 fourth and 3.00 reverse, with the 545RFE adding a 0.67 fifth (Chrysler). The difference is calibration. That is why the stamping and the label from Step 1 matter; they are how you tell the two apart without a scan tool.

The 68RFE is the one you can catch on the bench. Gears Magazine notes that Chrysler introduced the 68RFE for 2007 as the heavy-duty six-speed behind the 6.7L diesel (Gears Magazine). Sonnax's valve body identification guide gives the quick visual: natural metal-colored springs in the identification areas mean a 45RFE or 545RFE, while purple and orange springs mean you are holding a 68RFE (Sonnax 269). A 68RFE valve body will bolt into the same neighborhood, but it is not a 45RFE part.

Step 4: Pin Down the Year Generation

This is the step that saves money. Three things tell you which generation you have, and you should check at least two of them.

Solenoid pack connector color

Sonnax's identification chart lists black as 1999 through 2003 and 45RFE/545RFE only, white as 2004 through 2008, and gray as 2009 and later (Sonnax 269). Here is where it pays to know your sources disagree. A later Sonnax article describes the black connector as short-lived and replaced by white in 2000, with gray arriving in 2010 (Sonnax 1445), and Transmission Digest describes the change to the quieter white connector as a 2004 event (Transmission Digest). The practical lesson is the one every one of those sources agrees on: replace the pack with the same color that came out. The color is the fact; the year range is an approximation.

There is one allowed direction of swap. Sonnax notes that a white-connector pack could be used to service 2009-and-later units during dealer warranty work when gray packs were back-ordered, but a gray pack cannot back-service earlier units, because it is built for five solenoids, not six (Sonnax). If you want to confirm by meter, Sonnax lists every shift solenoid at about 1.3 ohms and the pressure control solenoid at about 3.5 ohms, with pin 7, overdrive solenoid control, not used on the late version (Sonnax 318).

Check ball count

Pull the valve body and count. Gears Magazine documents that the early 45RFE valve body used seven check balls and that the 2009 update dropped to five, eliminating the overdrive solenoid, the number 6 check ball that separated its circuit, and the number 7 check ball that went with the manual 2-L range (Gears Magazine). Seven balls means early. Five means late.

Separator plate stamp

Sonnax identifies the late plates by the number stamped in the small box between two bolt holes: 52120004A on 2009 to 2010 plates and 52120004AB on 2011-and-later plates (Sonnax 269). Early and late plates also differ in their vent and underdrive release holes, which Gears walks through if you ever have to cross the 2009 line with a core that does not match.

Remanufactured valve bodies are catalogued exactly along that line. Sonnax lists CHR140 for 45RFE and 545RFE 2008-and-earlier, and CHR141 for 45RFE and 545RFE 2009-and-later along with the 65RFE and 66RFE (Sonnax). Notice the part numbers split on year, not on 45 versus 545.

Step 5: Two-Wheel Drive or Four-Wheel Drive

This sounds obvious until you are ordering a filter kit or a fluid quantity for a transmission sitting on a stand. Chrysler's 2008 Ram capacity sheet gives the 45RFE and 545RFE service fill as 5.2 liters (11 pints) for 4x2 and 6.2 liters (13 pints) for 4x4, with an overhaul fill of 14 to 16 liters (29 to 33 pints) depending on cooler and line size (Ram Body Builder). A 4x4 unit has the transfer case adapter at the back instead of the 4x2 extension housing, and filter kits are sold by drive type for the same reason. Get it wrong and you are either short on fluid or returning a filter.

What the Shifter Tells You

The shifter is a free clue. Chrysler's operation description says the hydraulic system without electronic assist gives Park, Reverse, Neutral, Second and Third on driver selection, which is what the unit falls back to in limp-in. It also notes that vehicles with Electronic Range Select, such as the WK, WH, XK and XH, do not get second gear in limp-in because the lever has no 2 or 1 position (Chrysler). Gears adds that after the 2009 update the manual 2-L range was gone, manual control moved to tap up and down buttons, and limp mode became fourth gear only (Gears). A PRND2L column shifter points to an early unit; tap-shift buttons point to a late one. Confirm with the connector and check balls, but it narrows the search before the pan comes off.

Quick Identification Checklist

• Case stamping and label: left side, above the pan rail. Photograph both first.
• RFE or not: 23-pin case connector, line pressure sensor, two external ports (TCC apply and release, right side), cooler return filter.
• 45/545RFE or 68RFE: natural metal springs versus purple and orange springs in the valve body.
• Generation: connector color (black, white, gray), check balls (seven versus five), separator plate stamp (52120004A or 52120004AB on late plates).
• Drive type: 4x2 extension housing and 5.2 L service fill versus 4x4 adapter and 6.2 L service fill.

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Frequently Asked Questions

Where is the ID number on a 45RFE transmission?

Chrysler stamps the transmission identification numbers on the left side of the case, just above the oil pan sealing surface, and attaches a label to the case above the stamped numbers. Chrysler says to use this information when ordering replacement parts. Clean the area before reading it, because the stamping is shallow and usually covered in road film.

How can I tell a 45RFE from a 545RFE?

Externally you usually cannot, because they share the case, gear train and valve body architecture. The difference is the calibration: the 545RFE uses a 0.67 fifth gear that the 45RFE never commands. Use the case stamping, the label and the vehicle build data to confirm the model, then use the connector color, check ball count and separator plate stamp to confirm the year generation for parts.

How do I tell a 45RFE valve body from a 68RFE valve body?

Sonnax's identification guide uses spring color. Natural metal-colored springs in the identification areas mean a 45RFE or 545RFE valve body. Purple and orange springs mean a 68RFE. The 68RFE is the heavy-duty six-speed introduced for 2007 behind the 6.7L diesel.

What do the solenoid pack connector colors mean on a 45RFE?

Black is the earliest pack and is 45RFE and 545RFE only, white is the long-running middle design, and gray is the late five-solenoid pack with no overdrive solenoid. Sources disagree by a year or so on exactly when each change happened, so replace the pack with the same color that came out of the transmission rather than ordering by model year alone.