The 2023 Ram 3500 with the 6.7L Cummins is fundamentally a solid heavy-duty platform, but the Aisin AS69RC transmission and its cooling/mounting system are weak points that surface earlier than they should on a truck this expensive.
Transmission Oil Cooler Failure / Contamination
Common · high severity
Typical onset: 40,000-80,000 mi
Symptoms: Transmission running hot (220°F+), especially under load or towing, Metal debris in transmission fluid during service, Milky or discolored ATF indicating coolant cross-contamination, Erratic shifting or limp mode after extended highway driving
Fix: Replace transmission oil cooler, flush entire cooling system and transmission lines, often requires new torque converter if contamination reached it. 6-9 hours labor depending on whether converter swap is needed. This is THE big-ticket item on these trucks.
Estimated cost: $2,200-4,800
Transmission Mount Failure
Common · medium severity
Typical onset: 50,000-90,000 mi
Symptoms: Clunk or thud on throttle tip-in or deceleration, Vibration through cab at idle in gear, Visible sagging or torn rubber in mount upon inspection, Exhaust contact or driveline angles off when loaded
Fix: Replace transmission crossmember mount. The factory mount is undersized for towing duty and deteriorates fast. Aftermarket heavy-duty options exist. 1.5-2.5 hours labor.
Estimated cost: $350-650
Overdrive Solenoid / Shift Solenoid Pack Faults
Occasional · medium severity
Typical onset: 60,000-110,000 mi
Symptoms: Check engine light with P0750, P0765, P0868 codes, Harsh 5-6 or 6-5 downshifts, especially under moderate load, Intermittent no-overdrive condition, Delayed engagement into gear after sitting
Fix: Replace solenoid pack in valve body. Pan drop, valve body R&R, solenoid replacement, new fluid and filter. 4-6 hours labor. Critical to use OE Mopar solenoids—aftermarket units fail within months.
Symptoms: Shudder or vibration at 40-50 mph during light throttle (feels like rumble strips), Lockup clutch cycling on/off repeatedly in 6th gear, Transmission slipping between 1,500-2,000 RPM under load, Fluid smells burnt even with recent change
Fix: Torque converter replacement requires transmission removal. 10-14 hours labor. If fluid is heavily contaminated, full rebuild is often the better economic move at this point. Converter-only fix works if caught early.
Estimated cost: $2,800-4,200
Transmission Cooler Line Leaks at Fittings
Occasional · medium severity
Typical onset: 30,000-70,000 mi
Symptoms: ATF drips or puddles under front of truck after sitting, Low transmission fluid warning on dash, Visible seepage at rubber hose-to-hard line junctions near radiator, Burnt ATF smell from fluid contacting exhaust crossover
Fix: Replace cooler lines and upgrade fittings to higher-quality clamps or AN fittings. Lines corrode from road salt. 2-3 hours labor if caught before major leak occurs.
Estimated cost: $450-850
Fuel Filter Housing Leak (Cummins-Specific)
Common · low severity
Symptoms: Diesel smell in cab or near driver door, Visible fuel weeping from filter housing base, Hard starting in cold weather after sitting overnight, Fuel puddle on frame rail or driveway
Fix: Replace fuel filter housing o-rings or entire filter head assembly. Often triggered by over-tightening during service. 1-1.5 hours labor. Use Mopar/Fleetguard parts—cheap filters cause this repeatedly.
Estimated cost: $250-500
Owner tips
Service transmission fluid and filter every 30,000 miles if towing regularly—Aisin spec calls for 60k but real-world towing accelerates wear dramatically.
Install an aftermarket transmission temp gauge; factory gauge is not granular enough to catch overheating before damage occurs.
Inspect transmission cooler lines and mounts annually—road salt eats the lines and mount rubber degrades faster than the rest of the drivetrain.
Use only Mopar ATF+4 or Aisin-approved fluid; other 'compatible' fluids cause solenoid and converter issues within 20k miles.
If buying used, pull transmission pan and inspect for metal—these trucks hide abuse well until the trans lets go suddenly.
Excellent engine, mediocre transmission execution—budget $3-5k for trans work by 100k if it's been towing, otherwise a capable long-term keeper.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Fitment notes: Dual battery system standard on 6.7L Cummins; auxiliary battery also Group 94R AGM
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Every control module on the 2018-2023 Dodge Ram 3500 — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Electric Power Steering Module (EPS)2.5 hr R&Rsecurity gateway +0.8 hr▸ programming details
📍 Integrated with steering column assembly, below instrument panel
🔧 wiTECH 2.0 or Autel MaxiSys Elite/Ultra
⚠️ Requires steering angle sensor calibration and end-stop learning procedure after replacement.
⚠️ Critical security module. Enforces Security Gateway protocol. Replacement requires dealer-level authentication and all modules may need reconfiguration.
Door Module (DDM/PDM)1.2 hr R&Raftermarket tool +0.3 hrwith power windows/locks▸ programming details
📍 Inside door panel, driver and passenger doors
🔧 Autel MaxiSys or wiTECH 2.0
⚠️ Controls window, lock, and mirror functions. Requires window auto-up/down relearn after replacement.
⚠️ Monitors DEF quality and level. Requires system reset after replacement.
Seat Control Module (SCM)0.8 hr R&Rrelearn only +0.2 hrwith power seats and memory▸ programming details
📍 Under driver and passenger seats
🔧 Scan tool with bi-directional control
⚠️ Controls seat position, heating, ventilation, and memory. Requires memory position relearn after replacement.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2023 Dodge Ram 3500 6.7L I6 Cummins Diesel and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.