5R55S Identification Guide: Telling the 5R55S, W, N and E Apart

Half the 5R55 calls I get start with the wrong name. Somebody pulled a "5R55E" out of an '04 Explorer, or bought a "5R55W" solenoid pack for a Mustang, or has a Lincoln LS on the lift and isn't sure whether it's an N or an S. These units share a family name and a lot of external shape, but the parts don't cross the way the names suggest. The rebuild kit, the solenoid pack, the valve body and even the filter depend on knowing exactly which one you have.

Here's how I identify a 5R55 before ordering anything, from the door label down to the solenoid body. The facts come from Ford's service information and owner guides, Sonnax, and ATRA, all listed at the bottom.

Recommended 5R55S parts

Once you know which unit you have: a 5R55S master kit, the updated 9L2Z-7G391-AA solenoid pack for 2004-on W/S units, and the separate 5R55E kit for Rangers. Secure checkout on site.

5R55S Master Rebuild Kit 2002

$312.99View part

5R55W Transmission Solenoid Block Pack, 9L2Z-7G391-AA

$232.99View part

Ford 5R55E Transmission Master Rebuild Kit 1997-Up

$223.99View part

The 5R55 family at a glance

There are really two families wearing the same number, and they're not related the way the letters suggest.

The 5R55E is the older one. Sonnax traces it back to the 4R44E, which showed up in 1995 behind the 2.3L and 3.0L engines in Ford and Mazda rear-drive trucks. For 1996 the 4.0L got beefier internals and the unit became the 4R55E. For 1997 Ford made it a 5-speed by using the front servo to get an overdriven first and fifth, and from then on it was either a 5R44E or a 5R55E. That's the Ranger, the Mazda B-series and the 1997-2001 Explorer. It's an A4LD descendant.

The 5R55N, 5R55W and 5R55S are a different design. Ford's 5R55W/S diagnosis manual describes the W/S as a 5-speed with a 4-element torque converter with TCC, 3 compound planetary gear sets, 3 bands, 3 multi-plate clutches and 2 one-way clutches. Per Sonnax's "5R55 Alphabet" article:

The Mustang row comes from Ford's own 2007 Mustang owner guide, which lists the 5R55S as the five-speed automatic. The 2007 Explorer guide lists it as well. The point of the table is simple: the model year and platform get you most of the way there, but the overlap years (2002-2005 Explorers, 2002-2003 Lincolns and T-Birds) are exactly where people order wrong.

Step 1: read the door label, not the forum

The fastest correct ID is on the driver's door jamb. Ford's diagnosis manual says the transmission code is on the vehicle certification label on the driver's door post, in the space marked TR, next to the space marked AXLE. For the 2002 Explorer and Mountaineer, Ford gives the codes as:

• R = 5R55W
• V = 5R55S

Here's the catch: the letter isn't the same on every platform. Ford's 2007 Explorer owner guide lists V for the five-speed automatic (5R55S) and X for the six-speed automatic (6R60). Ford's 2007 Mustang owner guide lists L for the 5R55S, with F and K used for the T5 and TR3650 manuals. So an "L" on a Mustang and a "V" on an Explorer are both a 5R55S. Always read the code against the transmission code table in that vehicle's own owner guide, which is in the "Identifying your vehicle" part of the maintenance section.

The Explorer listing matters for another reason. By 2006 the V8 Explorer had moved to the 6R60 six-speed, so a 2006-2010 Explorer isn't automatically a 5R55S. If the TR box says X, stop. You're working on a different transmission, and nothing in this guide or in a 5R55 kit applies.

If the label is missing or painted over, which happens on trucks that have been in a body shop, go to step 2.

Step 2: the service tag on the case

Ford also says the transmission can be identified by the service identification tag attached to the transmission case, and shows its location in the component-location figure in the same manual. On a unit that's still in the vehicle, it's a quick look with a light and a mirror. On a used unit sitting on a pallet, the tag is the only reliable ID you have, so check that it's still there before you pay for the core.

Write down everything on the tag: the model, the assembly part number and the build code. When you call a parts counter or a rebuilder, give them the tag information along with the year and engine. That's what separates a 2003 unit from a 2004 unit in the same model, and on the W/S, that year break matters for the solenoid pack (see step 4).

Step 3: case features you can see and feel

When the paperwork is gone, the case itself tells you a lot. Sonnax's identification notes give the tells.

5R55N vs 5R55W/S

Look just behind the intermediate servo cover. The N has two cast bosses there, and one of them is tapped for the PCC pressure port. The W and S have only one cast boss, for the PCC pressure port. That's the easiest external check, and you can often feel it with the unit still in the car.

Drop the pan and the difference is clearer. Sonnax notes that the N uses a base plate similar to a 4R70W's, with a reverse pressure (RP) switch, and its solenoid assembly has RP switch terminals. The W/S has no RP switch.

5R55W vs 5R55S

This is where the case doesn't help much. The W and S share the case and look almost identical from outside. Sonnax says the difference is in the hard parts, and the clearest one is in the overdrive planetary: the W uses a 24-tooth overdrive sun gear and the S uses a 38-tooth sun gear. That's why the two have different ratios in the gears the overdrive planetary affects, and why you can't mix W and S geartrain parts and expect the PCM to accept the result. On a teardown, count the sun gear teeth. With the unit assembled, rely on the door code and the tag.

5R55E vs everything else

The 5R55E has the A4LD layout. It uses one electronic pressure control (EPC) solenoid, shift solenoids and a TCC solenoid, where the W/S uses three pressure control solenoids (more on that below). Its applications don't overlap the W/S in the same model year either: an Explorer with a 5R55E is 2001 or earlier, and a Ranger automatic from this era is a 4R44E, 4R55E, 5R44E or 5R55E, never a W or S. Sonnax also notes that the 4R and 5R versions of this family use different separator plates. After the modifications in Sonnax's tips, the casting can be used for either one, so don't assume a 4R valve body won't fit a 5R case, and don't assume it will without checking the plate.

Step 4: the solenoid body is its own ID check

This is the step people skip, and it's where the expensive mistakes happen.

Ford's diagnosis manual says the PCM runs the W/S through 4 on/off shift solenoids (SSA, SSB, SSC, SSD), one PWM solenoid for TCC control, and 3 pressure control solenoids (PC-A, PC-B and PC-C) for line pressure and band and clutch apply pressure. All of those are on one solenoid body that bolts to the valve body.

Sonnax warns that the solenoid assembly looks interchangeable between the N, W and S, but the base plate and the filter are the critical parts. Mix them up and you can lose reverse, TCC apply and solenoid oil pressure. Match the base plate and filter to the unit.

Then match the pack to the year. ATRA's 2013 seminar manual gives the Ford part numbers:

The split is by year, not by W versus S. ATRA traced a common rebuild complaint, a flare on the 2-3 shift during the road test, to a replacement solenoid pack that didn't match the unit. The pressure control solenoids set line pressure and control band and clutch apply, so a small difference in their output changes shift feel a lot. If you're reading the part number off an old pack to order a new one, check it against this table first. The old one may already be the wrong one.

Step 5: confirm with the scan tool and the fluid check

Once you know which unit it is, two quick checks confirm you're looking at a healthy example of it.

Scan data. Ford's manual says the PCM uses the TFT sensor to set control pressure, shift schedule and TCC operation. Watch TFT, commanded gear and TCC on the scan tool on a road test. A W/S that runs out of gear-ratio codes (P0732, P0733, P0735) after someone mixed W and S geartrain parts will show a ratio the PCM doesn't expect. That points to an identification error made during a previous repair.

Fluid level, done Ford's way. These units have no dipstick. Ford's 2007 Mustang guide says so directly, and says the fluid type is marked on the transmission fluid pan or extension housing. That marking is one more thing to read while you're under there. Ford's W/S servicing procedure checks level at the fluid level indicator plug with the engine idling at about 650 rpm and TFT between 81 and 120°F (27-49°C), per the TFT PID. The spec is MERCON V. Capacity depends on the vehicle: Ford/Mitchell gives 12.6 qt (12.0 L) for the 2002 Explorer W/S, the 2007 Explorer guide gives 12.4 qt (11.7 L) for the 5R55S, and the 2007 Mustang guide gives 11.9 qt (11.2 L). Ford notes these are approximate dry-fill numbers and that the check procedure sets the actual level. Our 5R55S fluid guide goes through the fill.

Common ID mistakes I see

1. Calling every Explorer five-speed a 5R55E. Only 2001 and earlier. The 2002-up Explorer is a W or S (or a 6R60 in later V8s).
2. Ordering by W or S when the part splits by year. The solenoid pack is the classic case: a 2003 W and a 2003 S take the same early pack, and a 2004 unit of either type takes the later one.
3. Assuming a used N will bolt into an S application. The case bosses, base plate, RP switch and solenoid terminals are all different.
4. Building a W with S geartrain parts, or the other way around. The overdrive sun gears are different (24-tooth vs 38-tooth), and so are the ratios.
5. Buying a core with no tag. Without the tag you're guessing, and a 2003 and a 2004 unit look the same on a pallet.

Need parts for this job?

Once you know which unit you have, our 5R55 parts page has 5R55S and 5R55W master and overhaul kits by year range, the 9L2Z-7G391-AA solenoid block pack, valve bodies, and 5R55E kits and solenoids for the Ranger. Checkout is on site.

FAQ

How do I know if I have a 5R55S or a 5R55W?

Check the TR code on the vehicle certification label on the driver's door jamb. On the 2002 Explorer and Mountaineer, Ford uses R for the 5R55W and V for the 5R55S. The two share a case, so if the label is gone, use the service tag on the case. On a teardown, the W has a 24-tooth overdrive sun gear and the S has a 38-tooth one.

What does the TR code on a Ford door label mean?

TR is the transmission code, printed next to the AXLE code on the Safety Compliance Certification Label. The letters vary by platform: the 2007 Explorer uses V for the 5R55S and X for the 6R60, and the 2007 Mustang uses L for the 5R55S. Read it against the code table in that vehicle's owner guide.

Is the 5R55E the same as the 5R55S?

No. The 5R55E comes from the 4R44E/4R55E family used in the Ranger, Mazda B-series and 1997-2001 Explorer. The 5R55N, W and S are a different design with three bands and three pressure control solenoids. Rebuild kits, valve bodies and solenoids don't interchange between the two families.

Are 5R55W and 5R55S solenoid packs interchangeable?

The pack splits by model year, not by W or S. Per ATRA, 2002-03 Ford W or S units and 2003 Lincolns use 1L2Z-7G391-AG. 2004-on Ford and 2004-06 Lincoln use the later pack, and Ford recommends the updated 9L2Z-7G391-A. The wrong pack can cause a 2-3 flare. Sonnax adds that the base plate and filter have to match the unit.

Related guides

• 5R55S vs 5R55W: Differences, Interchange, and Which You Have
• 5R55S Fluid Type and Capacity
• 5R55S Shift Solenoid Symptoms
• 5R55S Rebuild Cost and What Drives It
• Ford 5R55S and 5R55W Transmission Problems