C0020 on 2017-2018 Ram 3500: ABS Pump Motor Failure Causes and Fixes

What's Unique About the 2017-2018 Ram 3500

This issue is notoriously common on 2017-2018 Ram 2500, 3500, 4500, and 5500 trucks, to the point of prompting a class-action lawsuit, *Wilson et al. v. FCA US LLC*. A manufacturer Technical Service Bulletin (TSB) specifically advises that for this code, the Hydraulic Control Unit (HCU) can often be replaced by itself, without needing to replace the more expensive electronic control unit (ECU/ABS module). This is a critical distinction, as it can save significant money on parts. However, parts availability has been a major issue for owners, with some waiting months or even over a year for a replacement. The settlement of the lawsuit resulted in a voluntary safety recall (NHTSA Recall No. 24V-896) to install a new HCU with improved motor brush material.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• ABS warning light illuminated on the dashboard.
• Traction control/Electronic Stability Control (ESC) warning light on.
• "Service Electronic Braking System" message on the instrument cluster. [NHTSA ODI #11561898]
• Cruise control becomes inoperative or disengages unexpectedly. [NHTSA ODI #11561790]
• Loss of anti-lock braking function, wheels may lock and skid during hard braking.
• Intermittent activation of warning lights and chimes, often triggered by bumps, vibration, or driving on rough roads. [13, 14, NHTSA ODI #11609806, 6]
• Some owners report the issue is more frequent in cold temperatures. [NHTSA ODI #11561790]

Most Likely Causes

1. Failed Hydraulic Control Unit (HCU) / ABS Pump Motor 🔴 High Probability → Shop ABS Control Module This is a widely documented failure point, subject to a TSB, a class-action lawsuit, and a recall. The internal electric motor's carbon brushes can get stuck in their housing due to debris or a tight fit, failing to maintain contact with the commutator. This creates an intermittent open circuit, triggering the fault.
   How to confirm: With the vehicle running, lightly tapping on the black, cylindrical ABS 🎬 Watch: How to perform the tap test on the motor. pump motor may trigger the warning lights and chime, strongly indicating an internal mechanical/electrical issue inside the motor. A diagnostic scan tool will confirm the C0020-01 code is active.
   Typical fix: Replace the Hydraulic Control Unit (HCU). Per TSB #9004246 and STAR Case S2005000004, the HCU can be replaced separately from the main ABS electronic module. The system must be professionally bled afterward using a scan tool's ABS bleed function.
   Est. part cost: $220-$820
2. Poor Wiring Connection or Damaged Harness 🟡 Medium Probability The main electrical connector to the ABS module is located in the driver's side wheel well and is exposed to the elements. Vibration and moisture can lead to loose or corroded terminal pins, causing intermittent connections. Sand and dirt can also accumulate inside the connector, causing issues.
   How to confirm: Visually inspect the large connector and wiring harness going to the ABS module. Check for corrosion, pushed-out pins, or chafed wires. Wiggling the harness with the key on may cause the fault to appear or disappear. Some owners have had to remove the connector's red cap, push out individual wires, and re-tension the female pins to ensure a tight fit. In some cases, simply disconnecting, cleaning with a vacuum 🎬 Watch: How to potentially fix the connection for free. or contact cleaner, and reseating the connector has resolved the issue.
   Typical fix: Clean the connector terminals with contact cleaner. If a pin is loose, it may need to be carefully removed and re-tensioned. Repair any damaged sections of the wiring harness.
   Est. part cost: $0-$50
3. Failed ABS Control Module (ECU) ⚪ Low Probability → Shop ABS Control Module While less common than the HCU failure, the electronic module itself can fail. The manufacturer TSB acknowledges this possibility but explicitly recommends replacing the HCU first.
   How to confirm: This is typically diagnosed by exclusion. If a new HCU is installed and properly bled, and the C0020-01 code immediately returns, the ECU is the likely culprit.
   Typical fix: Replace the ABS Control Module. This part is often sold separately from the HCU and bolts onto it with T20 Torx screws.
   Est. part cost: $500-$900

Rare But Worth Checking

• Poor Ground Connection: A high-resistance or open ground circuit for the ABS module can cause a variety of electrical faults, including C0020. This should be checked with a multimeter at the module's connector before replacing expensive components. A service manual for a similar platform notes to check ground circuits Z907 and Z908 for opens or high resistance.
• Blown ABS Fuse: A blown fuse for the ABS module or pump will cause a loss of power and trigger fault codes. For 2013-2018 Ram trucks, the relevant fuses are typically located in the under-hood fuse box (Power Distribution Center). The primary fuses to check are F06 and F26.

Diagnosis Steps

1. Confirm the active trouble code is C0020-01 using a capable OBD-II scanner like AlfaOBD.
2. With the engine running, locate the ABS module/HCU in the driver-side front wheel well and lightly tap the pump motor. If the warning lights appear or flicker, the HCU motor is almost certainly the fault.
3. If the tap test is inconclusive, turn the ignition off. Disconnect the main electrical connector from the ABS module.
4. Thoroughly inspect the connector and wiring harness for any signs of corrosion, damage, or loose pins. Wiggle the harness to check for intermittent breaks.
5. If wiring appears intact, check for good power and ground at the ABS module connector using a multimeter, per the factory service manual. Check for battery voltage at the fused B+ circuit (often designated A901) and check for resistance to ground on the ground circuits (Z907/Z908), which should be less than 5 ohms.
6. If power and ground are good, the fault is highly likely to be the HCU/pump motor itself. Follow TSB #9004246 and replace the Hydraulic Control Unit (HCU).
7. After replacing the HCU, the brake system must be bled. This requires a scan tool with an ABS bleed function (like AlfaOBD or wiTECH) to cycle the pump and purge all air from the new unit, followed by a manual bleed of all four wheels.
8. Perform a test drive. If the code does not return, the repair is complete. If it does, the ABS electronic module (ECU) may also be faulty.

Parts You'll Likely Need

• ABS Hydraulic Control Unit (HCU) (OEM #68347099AB (or superseding 68347099AC)) — This is the most common failure point for code C0020 on this vehicle, as documented by owner complaints, a manufacturer TSB, and a subsequent recall.
  Trusted brands: Mopar
  OEM price range: $350-$850
  Aftermarket price range: $200-$600
• ABS Control Module (ECU) (OEM #68347098AB (superseded by 68347098AC)) — This is the electronic controller that operates the HCU. It is the second most likely part to fail, but TSB #9004246 advises replacing the HCU first.
  Trusted brands: Mopar
  OEM price range: $500-$980
  Aftermarket price range: $400-$700

Related Codes That Often Appear With This One

• C2200-49 (ABS Internal Electronic Failure): This code is often seen alongside C0020-01 and points to a failure within the electronic control module itself, though the root cause is often still the HCU pump motor causing an electrical fault that the module interprets as an internal failure. [NHTSA ODI #11580288, 18]

Technical Service Bulletins (TSBs) & Recalls

• 9004246: Advises that for DTC C0020-01, the Hydraulic Control Unit (HCU) can be replaced alone without replacing the ECU.
• S2005000004 Rev C: A STAR case file that provides the diagnostic flow for C0020-01, instructing technicians to replace the HCU first, test drive, and only replace the ECU if the code returns.

Platform-Specific Known Issues

• A class-action lawsuit, *Wilson et al. v. FCA US LLC*, was filed against FCA alleging that 2017-2018 Ram 2500, 3500, 4500, and 5500 trucks were equipped with defective HCU and ABS modules. The lawsuit has been settled, resulting in reimbursement for past repairs and a voluntary safety recall (NHTSA Recall No. 24V-896).
• TSB #9004246 and STAR Case S2005000004 specifically address code C0020-01, advising technicians to replace the HCU first before considering the ECU.
• Owners have reported significant backorders and parts shortages for the HCU and ABS modules, sometimes waiting months for a replacement, with some dealers quoting waits into the next year.
• Some owners have successfully repaired the HCU by disassembling the pump motor and freeing up stuck internal brushes. This involves carefully prying open the motor housing, cleaning the brush channels to allow free movement, and reassembling. This is a complex DIY repair but can save hundreds of dollars.
• Multiple owner complaints filed with the NHTSA document repeated failures, with some trucks needing multiple HCU replacements at low mileage. [ODI #11613324, ODI #11551695]

Mechanic-Grade Diagnostic Values

• Ground circuit resistance — expected: < 5.0 Ohms. Failure: Resistance above 5.0 Ohms indicates a poor ground.
• Voltage supply at ABS pump connector — expected: 12.0 - 12.6 V (Key On). Failure: Voltage below 11.5 V indicates a power supply issue (weak battery, alternator, or high resistance in the power feed circuit).

Scan Tool Commands That Help

• AlfaOBD / wiTECH: ABS Bleed / ABS Brake Bleed — This function is required after replacing the HCU or opening any brake lines. It cycles the internal solenoids and pump motor to purge trapped air that cannot be removed by manual bleeding alone.
• wiTECH: ABS Initialization — This function may be required after replacing the ABS module (ECU) to configure it to the vehicle. It can also be used to reset the module and calibrate sensors.
• wiTECH / Capable Scan Tool: Actuate ABS Pump Motor — This is a bidirectional test to command the ABS pump motor to run. It helps confirm if the motor is capable of operating when commanded directly by the scan tool, which can help differentiate between a faulty motor and a control-side problem.

Wiring & Ground Locations

• ABS Module Fuses — In the under-hood Power Distribution Center (fuse box), located on the driver's side near the battery.. Fuse F06 (J-case) and F26 are the primary fuses for the ABS module and pump. A blown fuse will cut power and cause code C0020.
• ABS Module Connector — On the ABS module itself, located in the driver's side front wheel well, behind the fender liner.. This large connector is the main interface for all power, ground, and sensor signals. It is exposed to moisture and debris, making it a common point of failure due to corrosion or dirt intrusion.
• Ground Circuits (Z907 / Z908) — These are the ground wires within the harness leading to the ABS module connector. The main chassis ground point is typically G300 on this platform.. A poor ground connection can cause a wide range of electrical faults in the ABS module, including the C0020 pump motor control fault.

Real Owner Repair Stories

• YouTube user 'cheeesman1' (2017 Ram 5500 with 58,000 miles) — Intermittent ABS/Traction control light (code C0020-01) when hitting bumps, loss of cruise control.
  ❌ Tried (didn't work) The HCU had been replaced once before by the dealer under warranty at 20,000 miles.
  ✅ What actually fixed it The owner disassembled the ABS pump motor and found one of the carbon brushes was stuck in its housing and not making proper contact. He sanded the sides of the brush slightly to allow it to move freely, reassembled the motor, and resolved the issue without replacing the HCU.
• YouTube user 'sradjoe' (2018 Ram 2500) — Intermittent "Service ABS" and "Service Electric Brake System" alerts with chime, traction and cruise control failure, code C0020-01.
  ❌ Tried (didn't work) Received a $1600 quote for service with no ETA on parts.
  ✅ What actually fixed it The owner removed the driver's side front fender liner, disconnected the main ABS wiring harness, and found a large amount of dirt and sand inside the connector. He cleaned the connector with a vacuum and reconnected it, which completely resolved the warning lights and codes.
• YouTube user 'Fixed It Myself' (2018 Ram 2500) — Intermittent "Service ABS System" warning light on the dash.
  ✅ What actually fixed it Similar to another DIY repair, the owner disassembled the ABS pump motor and found one of the two internal brushes was stuck and not moving freely. The other brush was working correctly. The fix was to free up the stuck brush, ensuring it could maintain contact with the motor's commutator.

OEM Part Supersession History

• 68347099AA, 68347099AB → 68347099AC — Part revision to address the common failure mode. The recall campaign involves replacing older units with an HCU that has improved motor brush material.