P0740 on 2000-2005 Dodge Neon: Torque Converter Clutch Circuit Fixes

What's Unique About the 2000-2005 Dodge Neon

The 2000-2005 Dodge Neon uses a 4-speed A604/41TE automatic transmission, an electronically controlled unit with a history of solenoid pack and torque converter issues across various Chrysler platforms. While the code points to an electrical circuit fault, it's frequently triggered on these transmissions by a mechanical failure, such as a worn-out torque converter clutch that can no longer maintain lock-up, causing excessive slip that the computer interprets as a fault. Owners often find themselves debating between replacing the more accessible solenoid pack versus the more labor-intensive torque converter. A common point of confusion is that the TCC solenoid is integrated into the main solenoid pack on this transmission, not a separate, individually replaceable part.

Symptoms You May Notice

• Check Engine Light is on
• Transmission may enter 'limp mode' (stuck in 2nd or 3rd gear)
• Shuddering or vibration at highway speeds, similar to driving over rumble strips
• Engine RPM is higher than usual at cruising speeds
• Noticeable decrease in fuel economy
• Stalling when coming to a stop
• Harsh, erratic, or delayed shifting
• Slipping or engine revving when trying to maintain speed on the highway

Most Likely Causes

1. Faulty Torque Converter Clutch (TCC) Solenoid / Solenoid Pack 🔴 High Probability → Shop Automatic Transmission Torque Converter The A604/41TE transmission family is known for solenoid pack failures. The solenoid is an electronic part that lives in hot transmission fluid and can fail over time. It is a very high-failure item.
   How to confirm: A technician can use a scan tool to command the TCC solenoid on and off to check its response. The solenoid's electrical resistance can also be tested with a multimeter after accessing it inside the transmission pan. The entire pack is often replaced as a unit.
   Typical fix: Replace the transmission solenoid pack, which contains the TCC solenoid. This is located on the front of the transmission, behind a side pan, and requires draining the fluid. 🎬 See: How to replace the solenoid pack
   Est. part cost: $100-$250
2. Failed Torque Converter 🔴 High Probability → Shop Automatic Transmission Torque Converter The internal clutch material within the torque converter can wear out, preventing it from locking up properly. This wear creates debris that contaminates the fluid and can damage other transmission components, including the new solenoid pack if not addressed. A manufacturer service bulletin, TSB Bulletin #9004009, notes that if a vehicle is jerking or slipping with code P0740 and the TCC solenoid is functioning correctly, the codes are indicative of a torque converter failure and the unit should be replaced.
   How to confirm: This is often diagnosed after ruling out the solenoid and wiring. If the transmission fluid is dark and full of metallic debris, it's a strong indicator of internal mechanical failure, likely the torque converter. A technician may also monitor TCC slip RPM with a scan tool; high slip (over 100 RPM) under lock-up command points to the converter.
   Typical fix: Replace the torque converter. This is a major repair that requires removing the entire transmission from the vehicle.
   Est. part cost: $150-$400
3. Low or Dirty Transmission Fluid 🟡 Medium Probability → Shop Transmission Assembly Incorrect fluid level or fluid that is old and contaminated with debris can prevent the solenoids and valves from operating correctly. These transmissions are very sensitive to fluid type and condition.
   How to confirm: Check the transmission fluid level and condition using the dipstick. The fluid should be at the correct level, pinkish-red in color, and not smell burnt. The correct fluid is Mopar ATF+4.
   Typical fix: Perform a transmission fluid and filter change. If the fluid is very dirty, a full flush may be recommended by a professional, but this may not fix an underlying mechanical issue.
   Est. part cost: $50-$150
4. Damaged Wiring or Connectors ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness going to the transmission for any signs of damage, corrosion, or loose connections. A multimeter can be used to check for continuity and shorts in the TCC solenoid circuit between the PCM and the transmission connector.
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the corroded connector.
   Est. part cost: $10-$100

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is very rare. The PCM should only be considered as the cause after all other possibilities (fluid, wiring, solenoid, and torque converter) have been exhaustively ruled out by a professional.
• Internal Hydraulic Leak: Excessive internal hydraulic leaks in the TCC circuit can cause the clutch inside the torque converter to wear out prematurely, leading to a recurring P0740 code even after replacing parts.

Diagnosis Steps

1. Scan the vehicle's computer to confirm the P0740 code and check for any other related codes, such as P0700.
2. Check the transmission fluid level and condition. Ensure it is filled with ATF+4 fluid. If the fluid is low, top it off. If it is dark, burnt, or contains debris, a fluid and filter change is necessary, but be aware this may not fix an underlying mechanical problem.
3. Visually inspect the transmission wiring harness and connectors for any obvious signs of damage, corrosion, or loose pins.
4. If possible, use an advanced scan tool to monitor the Torque Converter Clutch Slip Speed in real-time. If the slip is high (over 100 RPM) when lock-up is commanded, it points towards a mechanical issue (converter) or a hydraulic control issue (solenoid).
5. Perform electrical tests on the TCC solenoid circuit. This involves checking for proper voltage and ground signals at the transmission connector.
6. If the external wiring is good, the next step is to test the TCC solenoid itself. This requires removing the transmission side pan to access the solenoid pack and testing its resistance with a multimeter.
7. If the solenoid and wiring test good, the torque converter is the most likely culprit, requiring transmission removal for replacement.

Parts You'll Likely Need

• Transmission Solenoid Pack (OEM #5140429AA) — This pack contains the TCC solenoid, which is a common failure point. It's often replaced as a complete unit.
  Trusted brands: Mopar, ATP, Rostra, Autopart Premium
  OEM price range: $200-$300
  Aftermarket price range: $95-$200
• Torque Converter — The internal clutch of the torque converter can wear out, causing slip and triggering this code. It's the next most likely cause after the solenoid pack.
  Trusted brands: Mopar, Transtar, Pro-King
  OEM price range: $300-$500
  Aftermarket price range: $150-$300
• Transmission Filter and Gasket Kit — This is required whenever servicing internal transmission components like the solenoid pack.
  Trusted brands: Mopar, Wix, ATP
  OEM price range: $30-$50
  Aftermarket price range: $15-$30
• Mopar ATF+4 Transmission Fluid — This is the only specified fluid for the 41TE transmission. Using other fluids can cause shifting problems and damage.
  Trusted brands: Mopar, Valvoline (licensed)
  OEM price range: $8-$12 per quart
  Aftermarket price range: $7-$10 per quart

Related Codes That Often Appear With This One

• P0700 — P0700 is a generic transmission fault code that simply means the Transmission Control Module (TCM), which is integrated into the PCM on this vehicle, has stored a specific fault code. It almost always appears with other P07xx codes like P0740 to signal a transmission-related issue.

Platform-Specific Known Issues

• Real-World Repair Story: Solenoid Pack Replacement: → Shop Transmission Valve Body A user on DodgeForum.com with a 2004 Neon experiencing P0700 and P0740 codes, along with stuttering and slipping, reported fixing the issue by replacing the transmission solenoid pack and the input/output sensors. This was a relatively easy, one-hour job that resolved the codes and drivability problems.
• Transmission Re-learn Procedure: → Shop Transmission Assembly After replacing the solenoid pack, the transmission controller (PCM/TCM) may need time to adapt to the new part. While a formal 'quick learn' procedure with a dealer scan tool is beneficial, it is not strictly required to fix the P0740 code. The computer will eventually adapt its shift strategy over time through normal driving.
• Cross-Manufacturer Transmission Insights: → Shop Transmission Assembly While the Neon uses the 41TE, similar Chrysler platforms using the 62TE transmission also link P0740 to torque converter failure if the TCC solenoid is found to be operational, as noted in TSB Bulletin #9004206.

Mechanic-Grade Diagnostic Values

• TCC Solenoid Resistance (within solenoid pack) — expected: 1.0 - 2.0 Ohms. Failure: A reading outside this range (open circuit or shorted) indicates a failed solenoid coil.
• TCC Slip Speed (Live Scan Tool Data) — expected: Under 100 RPM when lockup is commanded. Failure: Sustained slip greater than 100 RPM points to a mechanical failure of the torque converter clutch or a hydraulic pressure issue.
• Solenoid Pack Connector Pinout (41TE/A604) — expected: Pin 4: 12V Input, Pin 7: L/R & TCC Solenoid Control. Failure: Use these pin assignments to test for voltage at Pin 4 and to test the resistance and continuity of the TCC solenoid circuit at Pin 7 back to the PCM.

Scan Tool Commands That Help

• Chrysler DRB III: Transmission Quick-Learn — This procedure should be performed after replacing the solenoid pack, torque converter, or the entire transmission. It forces the TCM to quickly relearn clutch volume indexes (CVIs) and shift adapts, which can resolve harsh shifting or erratic behavior that might otherwise take many drive cycles to resolve on its own.
• Chrysler DRB III or equivalent bidirectional scanner: Solenoid Actuation Test — To manually command the TCC solenoid on and off while monitoring the circuit's response. This helps isolate whether the fault is with the solenoid itself or the controlling circuit (wiring/PCM). A click should be heard from the solenoid, and voltage changes can be monitored.

Wiring & Ground Locations

• G101 — Located at the lower front of the engine block.. This is a primary ground for the PCM/TCM. A poor connection here can cause low voltage, erratic sensor readings, and incorrect operation of transmission solenoids, potentially triggering a P0740 code.
• G102 — Located at the left rear of the engine.. This ground is critical for the ignition coils, but poor engine grounding in general can introduce electrical noise that affects sensitive components like the PCM and transmission sensors.
• Chassis-to-Transaxle Ground Strap — A braided strap connecting the transmission case to the vehicle's chassis, often near the starter or a bellhousing bolt.. This is a critical ground path. If this strap is missing, corroded, or loose, the transmission solenoids may not have a reliable ground, leading to circuit codes like P0740 and erratic shifting.
• PCM Connector C2 (Black) — At the Powertrain Control Module (PCM) on the firewall.. The control wire for the TCC solenoid (often shared with the L/R solenoid) runs from this connector to the main transmission harness connector. Technicians can test for continuity and shorts on this wire directly from the PCM connector pin.
• Harness Chafe Point — The engine wiring harness may rub against brackets or the edge of the cylinder head near the back of the engine.. A forum post with pictures highlights a common spot where the harness can rub through, causing wires for transmission control (among others) to short to ground, leading to various electrical faults including P0740.

Real Owner Repair Stories

• DodgeForum.com user 'jeremy_mcelwain' (2004 Dodge Neon) — P0700 and P0740 codes, stuttering, slipping/engine revving then re-engaging.
  ✅ What actually fixed it The user replaced the transmission solenoid pack and the input/output speed sensors, along with a transmission filter and fluid change. This resolved the codes and shifting problems.
• NHTSA ODI #11161242 — An owner of a related Chrysler platform reported that the check engine light would not reset due to the P0740 code even after changing the valve body and related solenoids on the transmission, despite the vehicle having no issues while driving.
• NHTSA ODI #10453604 — An owner reported that their vehicle lost power and locked up while driving; a scanner showed code P0740, indicating a torque converter problem which required a transmission overhaul and torque converter replacement.

Documented NHTSA Reports

• NHTSA ODI #11630070: An owner reported a P0740 code and mentioned a recall on the transmission pump (Recall S 44), though noted the VIN did not apply to their specific vehicle.

OEM Part Supersession History

• Various early PNs for 1989+ A604/41TE → Updated Borg-Warner or Mopar Solenoid Pack (e.g., 5140429AA) — The design was updated for improved reliability.
  Heads up: When installing the updated solenoid pack on an earlier transmission that used a steel spacer plate between the solenoid and case, the plate MUST be discarded. The new design uses only a gasket.

Model Year Variations Within This Range

• 2000-2001: Early second-generation Neons (2000-2001) could still be equipped with the older 3-speed (31TH) hydraulic automatic transmission, which is a completely different unit and does not have the same electronic controls or set this specific code.
• 2002-2005: Starting in 2002, the 4-speed electronically controlled 41TE automatic became the standard automatic option, replacing the 3-speed. This article and code P0740 specifically apply to vehicles with the 41TE.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Head Gasket Failure 🔴 High — Common, especially on the 2.0L SOHC engine. Often occurs after an overheating event or can manifest as a slow coolant/oil leak.
• Motor Mount Collapse 🟠 Medium — Very common failure, particularly the upper passenger-side mount and lower torque struts ('dog bones'). Leads to excessive engine vibration at idle and clunking noises.
• Clear Coat / Paint Failure 🟡 Low — Widespread cosmetic issue where the clear coat peels and flakes off, particularly on horizontal surfaces like the roof, hood, and trunk. Extremely common for this generation.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A complete used transmission from a low-mileage donor car can be a cost-effective alternative to a professional rebuild, especially if a failed torque converter has contaminated the entire unit. Individual electronic components like the PCM are also good candidates for used purchase.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Check the transmission fluid from the donor car if possible. It should be pink/red and not smell burnt.
• Ask for a vehicle history report of the donor car to check for reported accidents or maintenance issues.
• For a complete transmission, look for a seller that offers a short warranty (e.g., 30-90 days) against DOA units.

OEM-only on this vehicle (don't cheap out):

• Mopar ATF+4 Fluid: While licensed versions from brands like Valvoline are acceptable, avoid generic 'universal' ATF fluids, as the 41TE is notoriously sensitive to fluid chemistry.

Aftermarket brands forum-validated for this vehicle:

• Solenoid Pack: Borg-Warner is a highly regarded OEM supplier. Rostra is another well-known aftermarket brand.
• Torque Converter: Transtar, Pro-King, and Mopar (remanufactured) are common choices.
• Filter/Gasket: Wix, ATP, Mopar.

Brands owners have reported issues with on this vehicle:

• Be cautious of unbranded, 'white-box' solenoid packs from online marketplaces. While cheap, their failure rate is reportedly high, often leading to doing the job twice.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0700 — A general transmission control system fault code that frequently accompanies P0740, indicating the TCM has requested the MIL illumination.

Frequently Asked Questions