P0740 on 2015-2021 Ram ProMaster City: Torque Converter Clutch Circuit Guide

What's Unique About the 2015-2021 Ram PROMASTER CITY

The Ram ProMaster City uses a 2.4L engine paired with a ZF-designed 948TE 9-speed automatic transmission, which is also found in many other Chrysler, Jeep, and Fiat vehicles. This transmission, particularly in early models (2015-2016), was known for having significant "growing pains" including harsh shifting, delayed engagement, and various DTCs. Many of these issues were addressed via numerous software updates for the Transmission Control Module (TCM). 🎬 Watch: Improving shift quality and addressing common 948TE software issues. In fact, the 2015 ProMaster City was included in a class-action settlement related to these transmission problems. It's important not to confuse this vehicle with the larger Ram ProMaster van, which uses a different 62TE 6-speed transmission. While TSBs for the 62TE often point directly to torque converter failure for P0740, the 948TE has a more complex history where software and other internal issues are also common culprits. [TSB 9004009]

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on
• Vehicle shudders or jerks at highway speeds
• Engine RPM is higher than usual when cruising.
• Noticeable decrease in fuel economy.
• Engine may stall when coming to a stop.
• Rough or harsh shifting.
• Transmission may feel like it's slipping or not engaging the final gear
• Transmission overheating due to lack of TCC lock-up.

Most Likely Causes

1. Low or Contaminated Transmission Fluid 🔴 High Probability → Shop Transmission Assembly The 948TE transmission has a specific and complex fluid level checking procedure and does not have a traditional dipstick. Incorrect fluid levels can easily cause shifting problems and DTCs. While marketed in the US as 'sealed for life', service intervals in other countries are as low as 60,000 km (approx. 37,000 miles).
   How to confirm: Check the transmission fluid level and condition. This must be done following the specific manufacturer procedure, which involves warming the transmission to a specific temperature (approx. 122°F or 50°C) monitored with a scan tool. A special dipstick tool (or a homemade 140mm rod) is inserted through the fill plug to measure the level. Fluid should be clean, red (Mopar 8&9 Speed ATF), and not smell burnt. Finding significant dark, gritty clutch material in the pan is a strong indicator of converter failure.
   Typical fix: Perform a transmission fluid drain and fill using the correct Mopar ZF 8&9 Speed ATF (Part # 68218925AA) or a compatible equivalent. The drain plug torque is 26 ft-lbs and the fill plug torque is 17 ft-lbs. A full service requires about 5 quarts.
   Est. part cost: $100-$200
2. Faulty Torque Converter Clutch (TCC) Solenoid 🟡 Medium Probability → Shop Automatic Transmission Torque Converter
   How to confirm: A professional technician can use a scan tool to command the TCC solenoid on and off to check its operation. The solenoid's internal resistance can also be tested with a multimeter to see if it's within specification. This is an electrical component that can fail, triggering the circuit code.
   Typical fix: Replace the TCC solenoid. This is located inside the transmission, often as part of the valve body.
   Est. part cost: $150-$300
3. Failed Torque Converter 🟡 Medium Probability → Shop Automatic Transmission Torque Converter Across many Chrysler platforms, P0740 is frequently an indicator of internal torque converter failure, where the clutch material has worn out. This can be accelerated by heavy use, typical for a commercial vehicle like the ProMaster City.
   How to confirm: This is typically diagnosed by exclusion. If the fluid, wiring, and TCC solenoid are all confirmed to be good, the torque converter itself is the likely culprit. A scan tool showing excessive slip RPM (over 100 RPM) when the TCC is commanded to lock is a definitive sign of internal clutch failure.
   Typical fix: Replace the torque converter. This is a major repair that requires removing the transmission from the vehicle. It is highly recommended to also flush the transmission cooler lines.
   Est. part cost: $400-$800
4. Wiring Harness or Connector Issue ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness going to the transmission for any signs of damage, corrosion, or loose pins at the main connector. A recall was issued for some 2015 models for improperly crimped terminals on the sensor cluster harness, which could cause sudden shifting to neutral and other issues. A technician can perform a continuity test on the TCC solenoid circuit between the connector and the Transmission Control Module (TCM).
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the faulty connector.
   Est. part cost: $20-$200

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM) or Transmission Control Module (TCM): → Shop Engine Control Module (ECM) This is very rare. Before replacing a module, all other possibilities (wiring, fluid, solenoids, torque converter) must be exhaustively ruled out. However, given the 948TE's history, ensuring the TCM has the latest software is a critical and more common fix.
• Internal Transmission Mechanical Failure: → Shop Transmission Assembly A clogged internal passage in the valve body or other mechanical failures can prevent the TCC from operating correctly. One specific known failure on the 948TE is a bolt that secures a hydraulic pressure valve inside the main shaft loosening or breaking, leading to a loss of oil pressure, gear slippage, and potential failure.

Diagnosis Steps

1. Check for any available PCM or TCM software updates FIRST. Many shift quality and DTC issues on the 948TE have been addressed with flashes.
2. Check the transmission fluid level and condition using the proper procedure for the 948TE transmission (requires scan tool for temp, special dipstick). If the fluid is low, burnt, or dirty, perform a fluid and filter change with the correct Mopar fluid.
3. Use a professional scan tool to read live data. Monitor the torque converter clutch slip speed and the command status for the TCC solenoid while driving at highway speed. Slip should be near zero when commanded to lock.
4. Inspect the transmission wiring harness and main connector for any visible damage, corrosion, or loose connections.
5. Using the scan tool, command the TCC solenoid on and off to verify its electrical function.
6. If the solenoid does not respond, test the circuit's continuity and check for power and ground at the solenoid connector.
7. If the solenoid and wiring are good but the code persists and slip is still present, the failure is likely the torque converter itself.
8. As a temporary measure or diagnostic aid, some owners perform a 'transmission reset' by turning the ignition to 'Run' (engine off), slowly pressing the gas pedal to the floor, holding for 10 seconds, then turning the ignition off before releasing the pedal. This can temporarily improve shift quality.
9. If repairs are performed, consider having a dealer perform the '9 Speed Transmission Quick Learn Procedure' outlined in TSB 21-013-16 to reset the adaptive learning.

Parts You'll Likely Need

• Torque Converter (OEM #68288460AA, 68289064AD) — Often the ultimate cause of P0740 when the internal clutch material wears out, especially if fluid is contaminated with debris.
  Trusted brands: Mopar, LuK, Precision of New Hampton
  OEM price range: $600-$900
  Aftermarket price range: $400-$700
• Torque Converter Clutch (TCC) Solenoid — This solenoid is the electronic component that directly controls the TCC lock-up function and can fail electrically or mechanically.
  Trusted brands: Mopar, Bosch
  OEM price range: $200-$350
  Aftermarket price range: $150-$250
• Automatic Transmission Fluid and Filter Kit (OEM #68218925AA (Fluid)) — Low or dirty fluid is a primary cause of transmission issues. A fluid and filter service is the first step in diagnosis and repair. The filter for the 948TE is internal and not serviceable without splitting the case.

Related Codes That Often Appear With This One

• P0700 — P0700 is a generic code that means the Transmission Control Module (TCM) has stored a fault code. It acts as a 'heads-up' that a more specific transmission code, like P0740, is present.
• P2764 — This code also relates to the Torque Converter Clutch Pressure Control Solenoid Circuit. The provided TSB for the 62TE transmission groups P0740 and P2764 together as pointing to the same potential failures (solenoid or torque converter). [TSB 9004009]

Technical Service Bulletins (TSBs) & Recalls

• 9004009: While this TSB is for the 62TE transmission (not used in the ProMaster City), it establishes a diagnostic pattern for FCA vehicles: if the TCC solenoid is functional, P0740 is indicative of torque converter failure. [⭐ MANUFACTURER TSB — highest authority]
• 18-063-17 REV. A: A software update for the PCM on 2015-2016 models to address various DTCs and improve performance.
• 21-013-16 REV. A: Describes the 'Quick Learn' procedure for the 948TE transmission in 2015-2016 models to improve shift quality after repairs or for customer complaints.

Platform-Specific Known Issues

• A Technical Service Bulletin (TSB #18-063-17 REV. A) was issued for 2015-2016 models to update the PCM software, addressing several DTCs and improving system performance. While P0740 is not explicitly listed, updating control module software is a good practice when diagnosing transmission issues.
• TSB 21-013-16 REV. A details a '9 Speed Transmission Quick Learn Procedure' for 2015-2016 models that can improve shift quality and may be required after certain repairs.
• The 2015 ProMaster City was included in a class-action settlement regarding the performance and reliability of the 9-speed ZF 9HP48 transmission, acknowledging widespread issues with harsh shifting and reliability in early models.

Scan Tool Commands That Help

• wiTECH: Quick Learn Procedure — Required after the transmission, valve body, or TCM is replaced, or when adaptation memory cells are cleared. It is also a primary step to address customer complaints of poor shift quality, per TSB 21-013-16.
• wiTECH: Valve Body Solenoid Learn — This procedure is specifically required when the valve body and/or the Transmission Control Module has been replaced to match the electrical system with the solenoids. It should NOT be confused with the more general 'Quick Learn'.
• wiTECH: TCC Solenoid Actuation Test — A technician can use this bidirectional control to command the TCC solenoid on and off while monitoring circuit data to confirm if the solenoid is responding to commands from the TCM.

Wiring & Ground Locations

• Main Engine/Transmission Ground Strap — A braided ground strap located on the transmission, often attached to a starter mounting bolt and connecting to the chassis frame near the transmission mount.. A poor or intermittent ground connection at this primary point can cause a wide range of unpredictable electrical problems, including incorrect sensor readings and erratic solenoid operation that could potentially trigger a P0740 code.
• Chassis Ground Point — A common grounding point for auxiliary components is a bolt stud near the under-hood fuse box. Other solid ground points can be made on the chassis by sanding to bare metal.. While not the primary ground for the transmission, ensuring all grounds are clean and secure is a fundamental step in diagnosing any electrical fault code. Some owners add a supplementary ground from the engine block to the chassis to improve electrical stability.

Real Owner Repair Stories

• Codeman's Auto YouTube Channel (Dodge Grand Caravan with 62TE) (Dodge Grand Caravan with 62TE transmission (different transmission but same manufacturer and a very similar P0740 diagnostic process)) — P0740 code returned instantly after being cleared, even with the engine off.
  ❌ Tried (didn't work) The diagnosis started by noting that an instant code return points to a hard electrical fault, not a mechanical/hydraulic issue that would require the engine to be running.
  ✅ What actually fixed it The mechanic diagnosed a dead short in the lockup solenoid circuit. The final fix was replacing the individual TCC solenoid, which is located inside the side cover of the 62TE transmission.

Model Year Variations Within This Range

• 2015-2021: The ProMaster City uses the Chrysler-built 948TE version of the ZF 9-speed. A key physical difference is that the 948TE has its Transmission Control Module (TCM) mounted on the side of the transmission case, whereas the ZF-built 9HP48 version (used in Honda, Acura, Land Rover) has the TCM on top of the housing.