47RE Ram 3500 Cummins Common Problems and Fixes

A Ram 3500 Cummins with a 47RE lives a different life than the same truck with a 2500 badge. The one-ton is the truck people buy to pull a gooseneck or a fifth wheel, and plenty of them spent their first twenty years hooked to something heavy. The transmission is the same 47RE that went into the 1996-2002 Ram 2500 Cummins, but the failures that bring a 3500 through the door lean harder toward heat, band holding and hard-part breakage than toward electronics.

This is the short list I work from on a 1996-2002 Ram 3500 Cummins with the 47RE, in the order I check things, with the published specs and tests behind each one. If the complaint is the 24-valve lockup and overdrive shuttle at cruise, that is an electrical diagnosis covered step by step in our 47RE Ram 2500 Cummins problems guide; the 3500 has the same PCM and ECM setup and the same fix.

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Why the 3500 Fails Differently

The 47RE shifts hydraulically by governor pressure through the first three gears, holds second with a band, and carries a lockup converter and a separate overdrive section. None of that changes between the 2500 and the 3500. The load does. A one-ton that tows heavy pushes more heat through the converter circuit, more torque through the shafts and more holding demand onto the kickdown band, so the 3500 list starts with the cooler circuit and works back into the hard parts.

Problem 1: Cooler Line Leaks and the 1994-1997 Recall

On the early trucks the first thing to look at is the cooler line connection at the case. NHTSA campaign 97V084000 covers 1994-1997 Dodge Ram trucks, roughly 960,000 units. The recall summary says that under certain high-load conditions the transmission fluid temperature can exceed the melting point of the material in the connector that retains the cooler line. The line can then come loose and spray fluid onto the exhaust manifold, with a risk of smoke or fire. The dealer remedy replaced the high-temperature side connector fittings with ones that use a stainless steel retainer.^[1]

A 1996-1997 3500 that tows is exactly the "high load" the recall describes. Check that the stainless retainers are at the case fittings and run the VIN for open campaigns. On every year, inspect the rubber line sections for swelling and seepage at the crimps.

Problem 2: Heat, Cooler Restriction and Lockup Slip Under Load

Bob Warnke's Sonnax write-up on 46/47RH-RE cooler and converter flow lists what cooler and converter problems look like from the driver's seat: 740/1740 lockup codes, TCC slip at high torque, delayed engagements, slow converter fill, excessive stall speed and hydraulic noise. He calls cooler restriction by far the most common issue, with the drainback fitting, the auxiliary or radiator-mounted coolers and the lines as the usual restrictions.^[2]

The mechanism matters on a tow truck. When the converter clutch is not applied, a restriction in the cooler return reacts on the largest diameter of the switch valve, pushing it toward its spring. Sonnax shows how the spools can then stage mid-circuit, which restricts converter and cooler flow even further, and notes this can become a problem as head pressure nears 80 psi or more.^[2] In other words, a partly plugged cooler on a 3500 does not just run the fluid hot. It moves the valve that controls lockup.

How I check it

1. Bypass and re-test. Sonnax's most effective verification is to temporarily bypass the cooler circuit and re-test. If the slip or noise goes away, go find the restriction.^[2]
2. Watch flow from idle through lockup. Monitoring cooler flow from Drive at idle through the completion of lockup isolates a converter restriction. Low flow until the TCC applies, then a slow apply or a slip and shudder on apply, points at restricted release oil inside the converter.^[2]
3. Then the valve body and pump. With noise, high pressure or TCC slip, Sonnax says to inspect the pressure regulator valve and bore for wear, and to remember that a worn converter cover bushing or crank pilot lets the turbine shaft sealing rings cross leak.^[2]

Problem 3: Second Gear Slips or Flares When Loaded

The classic one-ton complaint: empty, the truck shifts fine. Hooked to a trailer, the 1-2 shift is soft, the 2-3 flares, or the engine flares on a 3-2 kickdown. Second gear on the 47RE is held by the front (kickdown) band, applied by the 2nd gear servo. Under trailer load the band has to hold far more torque, and a servo that leaks or a band that is out of adjustment shows up first on a 3500.

Start with the adjustment, because it is the cheapest fix and it gets skipped. From Chrysler's factory Ram service manual: front band adjusting screw to 72 in-lb, then back off 1-7/8 turns, locknut 30 ft-lb; rear band adjusting screw to 72 in-lb, then back off 3 turns, locknut 25 ft-lb.^[7] The front band adjuster is on the outside of the case. The rear band adjuster is inside the pan, so set it during a fluid service.

If the adjustment is right and it still slips in second under load, the fix is holding power, not more line pressure. The Sonnax 22301B-01K 2nd gear super hold servo kit fits the 46RH/RE, 47RH/RE, 48RE and A727. Sonnax rates it at 16% more apply area and 15% less leakage than other designs, says it gives more holding force in 2nd, firmer 1-2 shifts and 2-3 shifts that firm up under load, and lists the 22825-01 heavy-duty kickdown band strut as a recommended companion part.^[3] Sonnax also notes that a bigger servo reduces the need for aggressive lever ratios and excessively high line pressure, which is the right way to think about a tow rig.^[3] Read the instructions for the shift timing and overlap notes before you install it.

Problem 4: Engine Stalls Coming to a Stop When Hot

This one shows up on high-mileage 3500s and fools people. Cold, the truck is fine. As it warms up it starts to drag the engine at a stop, and eventually it stalls coming to a stop in gear. Mike Brown worked exactly this complaint on a 1999 Cummins 47RE in ATRA's GEARS magazine and laid out the order of attack: cooler flow, electrical, valve body, pump, converter.^[4]

1. Cooler flow. Loop the cooler lines to take the external cooler out of the picture. Then blow air into the rear cooler fitting at no more than 40 psi; it should enter with minimal resistance. You can also put the return line in a bucket and have a helper start it and put it in gear to watch flow.^[4]
2. Electrical. Unplug the transmission connector and test for the stall. Brown points out this is a valid test on the 47RE because it uses a governor pressure solenoid, not a line pressure control solenoid; on an EPC transmission, unplugging drives line pressure to maximum and can mask the problem.^[4]
3. Valve body. Inspect the switch valve bore for wear, and flat-sand the machined surfaces on glass with 220 wet/dry paper and soapy water, because warpage from years of service causes pressure losses and control oil leaks. If it still stalls, block the converter clutch valve, the converter clutch timing valve and the switch valve in their rest positions so lockup cannot happen through valve movement.^[4]
4. Pump. In Brown's truck it still stalled with the lockup valves blocked, and only after the front clutch applied. Air applied to the front clutch passage came out of both converter passages. The cause was a stator support warped at the feed holes, cross leaking front clutch oil into the converter circuit. Check the stator support with a flat file, and confirm with compression film or Plastigage.^[4]
5. Converter, last. Brown ranks it least likely, but notes an aftermarket multi-disc converter applies and releases more aggressively and can magnify a marginal valve body into a stall.^[4]

On a one-ton that has been towing, that warped stator support is worth checking on every rebuild, not just on stallers.

Problem 5: Broken Input Shaft

A 3500 that has been turned up and still tows heavy is the most likely truck in the shop to show up with no movement and a broken input shaft. Sonnax describes the input shaft failure rate in Dodge diesel transmissions as legendary, says the two-piece OE design suffers spline twist, shaft breakage and clutch hub failure, and calls it barely suitable for stock applications.^[5] Their upgrade parts for 47RH/RE and 48RE units are:

• 22121B-01 heavy-duty input shaft, for 1994-later units with the 1.245 in. sealing ring
• 22121B-02K Smart-Tech input shaft and piston kit
• 22121B-08K Smart-Tech big input shaft kit, which fits any 47RH/RE or 48RE converter with a 35-spline turbine hub^[5]

Ask about the tune and the trailer before you quote. Putting the stock two-piece shaft back into a 3500 that already broke one is quoting the same job twice.

Problem 6: Output Shaft Breakage

The other hard-part failure on a heavy-tow 47RE is at the back of the unit. Sonnax's extreme duty output shaft, part 22173D-01, is a 1.480 in. diameter shaft made from high-strength alloy with a larger 29-spline configuration based on the OE manual transmission spline. Transmission Digest reports it at 50% more strength than OE-size aftermarket shafts. It is aimed at 68RFE-to-48RE conversions, where the transfer case input has 29 splines, and at older 47RE applications when an appropriate 29-spline input gear is sourced separately.^[6] On a stock 47RE 4x4, that means the transfer case side has to change with it. Budget for that before recommending the shaft.

Fluid and Service on a Towing 3500

Plenty of 3500 problems start with a service done wrong. Chrysler's Ram service manual specifies Mopar ATF+4 (MS-9602), about 3.8 L (4.0 qt) for a pan-and-filter service, and 14-16 L for a dry fill, with the dry figure varying by cooler type and line length.^[7] Set the final level hot on the dipstick, not by the number. Pan bolts are 13 ft-lb and filter screws 35 in-lb.^[7] Do both band adjustments every time the pan comes off, and on a truck that tows heavy, service it on the severe-duty schedule, not the light-duty one.

The truck will also tell you when it is too hot. Above about 260 F the PCM forces a 4-3 downshift, applies the converter in third and turns on the O/D OFF lamp; fourth comes back at about 230 F.^[7] A 3500 owner who says "it drops out of overdrive and the light comes on when I pull a grade with the camper" is describing heat. Fix the cooling before you condemn the transmission.

Triage Order for a 1996-2002 Ram 3500 Cummins 47RE

1. Write down the engine (12-valve or 24-valve), any tuning, axle ratio, tire size and the trailer weight.
2. Inspect the cooler lines and case fittings; on 1996-1997 trucks, check the recall retainers.
3. Check fluid level and condition hot, then bypass the cooler and measure return flow.
4. Adjust both bands to spec, then road test loaded if you can.
5. Second gear slip under load after a correct adjustment: plan on a servo and strut upgrade at the rebuild.
6. Stall at a stop when hot: work cooler, electrical, valve body, pump, converter, in that order.
7. No movement on a tuned truck: expect the input shaft and quote the upgrade.

For fill specs and filter service, see our 47RE fluid type and capacity guide, and keep the transmission fluid spec chart handy for the rest of the fleet.

FAQ

What fails most often on a 47RE in a Ram 3500 Cummins?

On a one-ton that tows, heat-related problems lead the list: cooler restriction, lockup slip at high torque and 740/1740 codes. Sonnax calls cooler restriction by far the most common issue in the 47RE converter circuit. Second gear band slip under load and input shaft failure on tuned trucks follow.

Is there a recall on the Ram 3500 transmission cooler lines?

Yes, for 1994-1997 Dodge Ram trucks. NHTSA campaign 97V084000 covers cooler line connectors that could melt under high-load fluid temperatures and let the line come loose, spraying fluid on the exhaust. The remedy was connector fittings with a stainless steel retainer.

Why does my 47RE slip in second gear only when towing?

Second gear is held by the front kickdown band and the 2nd gear servo, and trailer load multiplies the torque they must hold. Check the band adjustment first: 72 in-lb, back off 1-7/8 turns, locknut 30 ft-lb. If it still slips, a larger servo such as the Sonnax 22301B-01K adds 16% more apply area.

Why does my 47RE stall the engine coming to a stop when hot?

The converter clutch is staying applied or oil is cross leaking into the converter circuit. Per GEARS, check cooler flow, unplug the transmission connector, then inspect the valve body switch valve. A warped pump stator support that leaks front clutch oil into the converter passages is a known cause.

Related 47RE guides

• 47RE Ram 2500 Cummins Common Problems and Fixes
• 47RE Towing Upgrades
• 47RE Overheating Prevention
• 47RE No Movement Diagnosis
• 47RE vs 48RE Differences