The 2018 RAM 3500 exhibits persistent failure of the hydraulic control unit (HCU) and ABS module, triggering warning lights, audible chimes, and disabling anti-lock brakes and traction control. Owners report this starting as early as 18,000 miles and recurring every 25,000–50,000 miles in some cases. One truck required HCU/ABS module replacement four times before 30,000 miles.
The core problem: dealers and parts suppliers cannot obtain replacement HCU or ABS modules. Mopar.com and dealer inventory show nationwide backorder with no confirmed availability. Owners have waited 3–8+ months without repair dates. One dealer explicitly stated the manufacturer halted new parts production pending internal investigation.
When braking fails catastrophically, owners report brake pedal going to the floorboard, rear-wheel lockup on wet roads, and in one case, complete hydraulic brake seizure while towing. One truck's brakes locked so tight the owner had to engage low-gear to separate it from a 20,000-pound trailer.
Even replaced parts fail identically within months. The newer-revision HCU (part 68143491-AB) reportedly fails as often as the original. Owners who self-repair or repair outside the official recall window are systematically denied reimbursement despite submitting proof of purchase and work documentation. RAM's recall (NHTSA 24V-896000, issued January 2024) remains "incomplete, remedy not yet available" as of February 2025.
Dealers advise not driving vehicles with active ABS faults but refuse to sell parts to independent shops. The combination of safety risk, unavailable parts, repeated defects, and denied claims leaves owners stranded with vehicles they cannot trade, sell, or safely operate.
Failure modes owners describe
Hydraulic Control Unit (HCU) failure
The HCU fails intermittently or completely, triggering Service ABS warnings and disabling ABS functionality. Owners report repeated failures of the same component at relatively low mileages.
When: Multiple reports starting as early as 18,000–25,000 miles; some repeated failures at 30,000–50,000 mile intervals; others at 60,000+ miles
Symptoms owners cite: Service ABS warning light and chime; Service Electronic Braking System warning; Intermittent or persistent ABS and traction control lights; Loss of ABS function; Cruise control disablement; Traction control failure
Codes mentioned: C0020, C0020-01
Repairs/costs cited: Replacement HCU required; dealers and online retailers report nationwide backorder. Replacement part numbers: 68143491-AA (original), 68143491-AB (newer revision). Repair costs $750–$2,000 when available. Multiple owners report the newer -AB part also fails.
Recalls/TSBs owners mention: Recall NHTSA 24V-896000 (Manufacturer Recall C4B) issued for 2017–2018 Ram trucks; remedy parts remain unavailable for extended periods. RAM reimbursement program denies claims if work was self-performed or if original receipt is unavailable. TSB (FCA STAR case S2005000004) documents diagnostic procedure to replace HCU first, then ABS module if fault persists.
ABS Module (control module/ECU) failure
The ABS control module fails either as a root cause or secondary to HCU failure. Some vehicles require replacement of both the HCU and ABS module to clear the fault.
When: Failures reported concurrent with or shortly after HCU failure; some as early as 4,000 miles, others at 20,000+ miles
Symptoms owners cite: Service ABS warning light; Service Electronic Braking System warning; Intermittent disabling of ABS and traction control; Cruise control disablement; Audible chime or alarm; No codes read on first diagnostic but fault returns on subsequent drives
Codes mentioned: C0020, C0020-01
Repairs/costs cited: Replacement ABS module/ECU required; availability equally constrained as HCU. Dealers state part requires dealer authorization for sale. Installation required; diagnostic cost runs $100–$200 before approval. Some dealers report difficulty sourcing the module nationwide.
Recalls/TSBs owners mention: FCA TSB (STAR case S2005000004, revised to Revision C) advises: replace HCU first, test-drive, and only replace ECU if C0020-01 fault persists. Recall 24V-896000 covers both parts; however, remedy parts unavailable as of latest complaints.
Brake system loss of function (complete or partial)
In some cases, owners report inability to stop the vehicle or severely reduced braking capacity. One owner reports the hydraulic brakes locked up entirely while towing; another reports brake pedal went to the floorboard before stopping.
When: Reported at various mileages including 27,200, 67,000, 191,000, and 200,000 miles
Symptoms owners cite: Brake pedal goes to the floorboard; Brakes fail to engage when depressed; Reduced braking capacity; Rear wheels lock up during braking; Front brakes overheat and seize; Service ABS and Service Electronic Braking System warnings; Loss of traction control
Codes mentioned: C0020, C0020-01
Repairs/costs cited: One owner reports front rotors, calipers, and brake lines damaged from overheating due to seized brakes; repaired but failure recurred. Another report documents brake lockup while towing 20,000-pound trailer; brakes had to be overcome manually to separate trailer. Replacement of HCU and/or ABS module required; parts unavailable.
Recalls/TSBs owners mention: Recall 24V-896000 issued; remedy parts unavailable. Dealerships advise not driving vehicle until repair available. One dealer informed owner brakes had seized due to HCU failure per recall scope but parts not in stock.
Parts availability and supply-chain failure
Owners cannot obtain replacement HCU and ABS modules from dealers, Mopar.com, or online retailers. Parts are repeatedly backordered with no firm delivery dates. One owner reports Mopar.com cancelled his order after requesting his VIN; another states dealer said new parts were halted pending internal investigation.
When: Ongoing from at least April 2023 through the time of latest complaints (February 2025)
Symptoms owners cite: Dealers state parts unavailable until future months (August, February, June with no confirmed dates); Multiple dealers and independent shops unable to locate parts; Mopar.com orders cancelled without explanation; Parts pulled from dealer inventory back to manufacturer; Nationwide shortage acknowledged by dealers and parts managers
Repairs/costs cited: Owners report waiting 3–8+ months for parts. One owner purchased used module online for $1,650 as a workaround. Another owner located a part via eBay from a RAM dealer and self-installed. Some dealers explicitly state parts will not be available for months or had manufacturing halted pending investigation.
Recalls/TSBs owners mention: RAM/FCA acknowledged parts shortage and stated new, more reliable versions being built but not expected for 4–6+ months. One dealer advised owner to wait until February 2024 while engineers worked on a fix. Recall 24V-896000 issued but remedy parts unavailable; recall status listed as 'Incomplete, remedy not yet available.'
Repeated failures of replacement HCU/ABS modules
Even after replacement, owners report the same fault code and symptoms recurring within months or after a few thousand miles.
When: First replacement at 5,374 miles, second at 13,136 miles, third at 20,607 miles, fourth at 29,769 miles (example from one truck). Another owner replaced HCU twice within 1 year; third failure imminent. Parts fail after 25,000–30,000 mile intervals in some cases.
Symptoms owners cite: Service ABS warning light returns; Service Electronic Braking System warning returns; ABS and traction control disabled again; Same fault codes (C0020, C0020-01) re-appear
Codes mentioned: C0020, C0020-01
Repairs/costs cited: One owner documents four replacements of HCU/ABS module over roughly 24,000 miles and 5 years. Replacement -AB part (newer revision) reported to fail as often as the original -AA part. Dealers unable to explain why replacement part fails similarly. Warranty on repairs limited to 10,000 miles per dealer.
Recalls/TSBs owners mention: No remedy offered. Dealers advise to 'let the part fail' and continue driving. Manufacturer denies reimbursement claims. One dealer informed owner there is no guarantee the replacement part will fix the vehicle because it is the same part number.
Recall reimbursement denials
Owners who proactively repair the HCU before or outside the recall window, or who self-perform repairs, are denied reimbursement by RAM customer care despite submitting proof of purchase and repair documentation.
When: Reimbursement requests made after recall issued (January 2024 and later)
Symptoms owners cite: RAM denies reimbursement citing 'no installation cited' or missing original receipt; Owners provide credit card statements, photos of old and new parts, proof of purchase; RAM customer care cites lack of 'installation' despite owner indicating self-performed work; Second appeal denied without recorded notes
Repairs/costs cited: One owner paid for and self-installed HCU, provided proof of purchase from dealer, credit card statement, and offered photographs; still denied. Another owner purchased used module on eBay for $1,650 and self-installed; denied reimbursement. Third owner paid $930 for repair in October 2022 (pre-recall) and again $957 for second failure in April 2025; recall center refuses reimbursement claiming repair was not performed on date listed.
Recalls/TSBs owners mention: Recall 24V-896000 issued with reimbursement program; however, RAM customer care denies claims for self-performed work or those lacking 'installation citation' or original dealer receipt. Owners who receive denial letters report appeals are ignored and communication channels are closed. One customer care email states: 'There is no installation cited and it is not eligible for reimbursement.'
Synthesized from 463 NHTSA owner complaints — unverified consumer
allegations, summarized for patterns. The verbatim filings appear below.