P0750 on 2006-2010 Dodge Charger 3.5L: Shift Solenoid 'A' Causes and Fixes

What's Unique About the 2006-2010 Dodge Charger

The 2006-2010 Dodge Charger with the 3.5L V6 uses a Mercedes-Benz NAG1 (also known as 722.6 or W5A580) transmission. A very common and well-documented issue on this specific transmission is the main 13-pin electrical connector plug leaking transmission fluid. The fluid wicks up the wiring harness due to capillary action, contaminating the pins and causing communication errors between the TCM and the solenoids, which directly triggers the P0750 code. This connector leak is often the root cause, rather than an actual solenoid failure, and should always be the first component checked.

Symptoms You May Notice

• Check Engine Light is on
• Vehicle is stuck in one gear (limp mode)
• Harsh or delayed shifting
• Transmission will not shift properly
• Reduced fuel economy
• Inability to use manual shift mode (AutoStick)

Most Likely Causes

1. Leaking Transmission Electrical Connector 🔴 High Probability → Shop Transmission Assembly The O-rings on the 13-pin electrical connector for the NAG1 transmission are a known failure point. Over time, they harden and allow fluid to seep past the seals, contaminating the electrical pins and causing a bad connection or short circuit.
   How to confirm: Visually inspect the round electrical connector on the passenger side of the transmission, near the front. Disconnect it (turn the bayonet collar counter-clockwise) and check for any signs of reddish transmission fluid inside the connector or on the pins. This is the most common cause and easiest check.
   Typical fix: Replace the electrical connector adapter plug, which includes new O-rings. The Mopar part number is 52108325AA. 🎬 Watch: How to identify and fix common electrical connector leaks. Clean the transmission-side and harness-side connectors thoroughly with electrical contact cleaner before reinstalling. This is a very common and relatively inexpensive fix.
   Est. part cost: $15-$40
2. Failed Solenoid Pack / Conductor Plate 🟡 Medium Probability The solenoids are electronically controlled valves that can wear out. More commonly, the conductor plate they are mounted to, which contains thin plastic electrical traces and speed sensors, can crack or fail, causing an open circuit. This is often the next most likely culprit after the connector leak is ruled out.
   How to confirm: After ruling out a connector leak and wiring issues, the next step is to test the solenoid's resistance. This requires dropping the transmission pan and valve body. The shift solenoids should have a resistance between 2.5 and 6.5 Ohms. A reading outside this range, or an open circuit, confirms a failure. Often, the entire conductor plate assembly is replaced as a unit.
   Typical fix: Replace the entire conductor plate assembly, which includes the solenoids and speed sensors. This is done as a single unit and is located on top of the valve body. 🎬 See this walkthrough on replacing the NAG1 transmission conductor plate. The OEM Mopar part number is often cited as 52108308AC, which supersedes previous numbers.
   Est. part cost: $150-$400
3. Low or Dirty Transmission Fluid 🟡 Medium Probability → Shop Transmission Assembly Low fluid levels can cause pressure issues, preventing solenoids from actuating correctly. Dirty or burnt fluid can clog the small passages in the solenoids and valve body. It is critical to use the correct fluid; this transmission does NOT use standard ATF+4. It requires a fluid meeting MB 236.14, 236.12, or 236.10 spec, such as Shell ATF 134 or Valvoline MaxLife ATF.
   How to confirm: These vehicles do not have a transmission dipstick from the factory. A special service tool (dipstick) is required to check the level via the dipstick tube at the back of the engine bay. The fluid level must be checked at a specific operating temperature. The fluid should be bright red and not smell burnt.
   Typical fix: Perform a transmission fluid and filter change. Ensure the correct fluid type is used (e.g., Shell ATF 134, Valvoline MaxLife ATF, or other MB 236.14 compatible fluid).
   Est. part cost: $75-$150
4. Wiring Harness Damage ⚪ Low Probability If fluid from a leaking connector has wicked far up the harness due to capillary action, it can corrode wires or the TCM connector itself. Physical damage to the harness from road debris or improper repairs is also possible.
   How to confirm: Perform a continuity test on the wires running from the 13-pin transmission connector to the Transmission Control Module (TCM). Check for open circuits, shorts to ground, or shorts to power. Visually inspect the harness for any chafing or damage.
   Typical fix: Repair or replace the damaged section of the wiring harness. In severe cases where fluid has saturated the harness up to the TCM, the entire engine harness may need replacement.
   Est. part cost: $20-$800

Rare But Worth Checking

• Failed Transmission Control Module (TCM): → Shop Transmission Assembly This is rare. The TCM is the computer that controls the transmission. It should only be considered after all other possibilities (solenoids, conductor plate, wiring, fluid) have been exhaustively ruled out. Sometimes a software re-flash at the dealer can resolve intermittent issues.

Diagnosis Steps

1. Scan the vehicle for all diagnostic trouble codes. Note any other transmission-related codes, especially for other solenoids or speed sensors.
2. CRITICAL FIRST STEP: Inspect the 13-pin transmission electrical connector on the passenger side of the transmission. Disconnect it and look for any signs of transmission fluid contamination. This is the most common failure point.
3. If fluid is present, replace the connector adapter plug (Mopar P/N 52108325AA) and thoroughly clean both sides of the connection 🎬 Watch: Step-by-step guide to replacing the transmission wiring adapter plug. with electrical contact cleaner before proceeding.
4. Check the transmission fluid level and condition using the correct service tool dipstick. The fluid must be at the correct level at operating temperature and should be clean, red, and not have a burnt smell. Ensure the correct fluid type (MB 236.14 spec) is being used.
5. If the connector is clean and the fluid is correct, inspect the wiring harness between the transmission and the TCM for any visible damage, corrosion, or loose connections.
6. If wiring appears okay, the next step is to test the internal components. Drain the transmission fluid and remove the transmission pan.
7. Remove the valve body to access the conductor plate and solenoid assembly.
8. Test the resistance of Shift Solenoid 'A'. It should be between 2.5-6.5 Ohms. An out-of-spec reading or open circuit confirms a failed solenoid. At this point, it is standard practice to replace the entire conductor plate assembly.
9. If the solenoid tests good, the issue may be in the conductor plate's internal traces or the TCM itself.

Parts You'll Likely Need

• Transmission Conductor Plate / Solenoid Assembly (OEM #52108308AC) — This assembly contains the shift solenoids and the electrical pathways/speed sensors that control them. The plastic plate can crack, causing electrical faults. This is the most common internal part to fail for this code.
  Trusted brands: Mopar, Bosch, URO Parts
  OEM price range: $250-$400
  Aftermarket price range: $150-$250
• Transmission Electrical Connector Adapter Plug (OEM #52108325AA) — The O-rings on this plug are a very common failure point on the NAG1 transmission, leading to fluid leaks that cause electrical faults like P0750. This should be the first part checked and is often the only part needed.
  Trusted brands: Mopar, URO Parts, Febi Bilstein
  OEM price range: $25-$40
  Aftermarket price range: $15-$25

Related Codes That Often Appear With This One

• P0751, P0752, P0753, etc. — These are codes for other shift solenoids ('B', 'C', etc.). If multiple solenoid codes appear, it strongly suggests a common electrical problem like the main connector leak, a failing conductor plate, a wiring issue, or a failing TCM, rather than multiple individual solenoids failing at once.
• P0717 — This code relates to the Turbine/Input Shaft Speed Sensor circuit. On the NAG1 transmission, these speed sensors are integrated into the conductor plate assembly. Seeing P0717 alongside P0750 is a strong indicator that the conductor plate itself has failed.

Technical Service Bulletins (TSBs) & Recalls

• While no TSB is directly for P0750, TSB 21-014-09 and similar software update bulletins exist for the NAG1 transmission to address various shift quality complaints. If the primary electrical and mechanical causes are ruled out, checking with a dealer for an available TCM software update is a valid diagnostic step.

Platform-Specific Known Issues

• A common owner experience shared on forums like ChargerForums.com involves a user getting a P0750 code, being stuck in limp mode, and successfully resolving it by replacing only the leaking 13-pin connector and cleaning the contacts. Many threads emphasize checking this simple, cheap part before attempting the more expensive conductor plate replacement.
• Another real-world scenario involves the fluid from the leaking connector wicking all the way up the wiring harness to the TCM, requiring the TCM to be unplugged and cleaned with electrical contact cleaner as well.

Mechanic-Grade Diagnostic Values

• 1-2/4-5 Shift Solenoid ('A') Resistance — expected: 4.5 Ohms. Failure: An open circuit (infinite resistance) or a reading significantly outside the expected value.
• 2-3 Shift Solenoid Resistance — expected: 4.5 Ohms. Failure: An open circuit or a reading significantly outside the expected value.
• 3-4 Shift Solenoid Resistance — expected: 4.5 Ohms. Failure: An open circuit or a reading significantly outside the expected value.
• Torque Converter Lock-up (TCC) Solenoid Resistance — expected: 2.7 Ohms. Failure: An open circuit or a reading significantly outside the expected value.
• Line Pressure Control Solenoid Resistance — expected: 5.5 Ohms. Failure: An open circuit or a reading significantly outside the expected value.

Scan Tool Commands That Help

• Chrysler WiTech or capable aftermarket scanner (e.g., JScan): Reset Learned Adaptives (NAG1) — This procedure must be performed after replacing the conductor plate, valve body, or transmission control module. It resets the transmission's self-calibrated shift points to factory settings, allowing it to re-learn the characteristics of the new parts for smooth shifting.
• Chrysler WiTech or capable aftermarket scanner: Store Learned Adaptives — After performing the adaptation drive cycle, this command can be used to manually force the TCM to store the new values immediately, rather than waiting for the automatic 10-minute interval.

Wiring & Ground Locations

• Transmission Control Module (TCM) — Located under the driver's side dashboard, below the steering column.. This is the control unit for the transmission. All solenoid resistance and continuity tests can be performed remotely from its main connector, saving the labor of dropping the transmission pan for initial diagnosis.
• TCM Connector Pin 38 — On the main connector for the Transmission Control Module.. Pin 38 is the common power or ground pin for all the shift solenoids in the NAG1 transmission. When testing solenoid resistance from the TCM, this pin is used as the common point for one lead of the multimeter.
• TCM Connector Pin 14 — On the main connector for the Transmission Control Module.. This is the specific control circuit pin for the 1-2/4-5 Shift Solenoid, which is often designated as Shift Solenoid 'A'. Testing resistance between pin 14 and pin 38 directly checks the integrity of the solenoid and its wiring.
• G202 — A primary ground point located behind the left side of the dashboard.. A poor ground at this location can cause a variety of electrical issues for dash-mounted modules, including the TCM. While not a direct cause of P0750, verifying this ground is good practice when chasing intermittent electrical faults.

Real Owner Repair Stories

• lxforums.com user (Dodge Charger with NAG1 transmission) — Vehicle went into limp mode, stuck in one gear. P0750 code was present.
  ❌ Tried (didn't work) Initial diagnosis pointed towards common issues.
  ✅ What actually fixed it The user replaced the conductor plate, which resolved the limp mode and cleared the P0750 code. The user noted the importance of also replacing the 13-pin connector plug and ensuring the correct fluid fill procedure was followed.
• NHTSA ODI #10208215 (Dodge owner) — An owner reported that their check engine light came on and they were forced to drive on the shoulder at 30MPH. A technician pulled a P0750 DTC code, which was described as a "Solenoid A fault." However, the transmission reset and the fault could not be replicated during a 13-mile test drive.

OEM Part Supersession History

• 52108308AB → 52108308AC — Part revision and improvement by the manufacturer.
  Heads up: 52108308AC is the correct and current replacement for earlier versions on this platform. Using older stock (AB) is not recommended.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• Shifter Stuck in Park ('Pink Thingy' Failure) 🔴 High — Extremely common. The small plastic park interlock lever inside the shifter assembly breaks, immobilizing the vehicle. It can happen at any mileage. (Ref: No recall for this specific part, but it is a widely known failure. Aftermarket metal replacements are the recommended permanent fix.)
• Intake Manifold Runner Control (MRC) Valve Failure 🟠 Medium — Common, often occurs after 60,000 miles. Causes rough idle, loss of power, and check engine light with codes like P1004. (Ref: No recall, but it's a frequent repair. The valve, located on the front of the upper intake manifold, gets stuck.)
• Rocker Arm Assembly Failure / Engine Ticking 🟠 Medium — A well-known issue on the 3.5L EGG engine. A dowel pin shears, causing the rocker arms to become misaligned and starved of oil, resulting in a loud ticking/tapping noise from the top of the engine.
• Front Suspension Component Wear 🟠 Medium — Common, especially after 70,000 miles. The tension struts (front lower control arms) and outer tie rod ends wear out, causing clunking noises over bumps, steering wheel vibration, and uneven tire wear.
• Timing Belt and Water Pump Replacement 🔴 High — This is a required maintenance item, not a failure. The 3.5L EGG is an interference engine. The timing belt must be replaced at the manufacturer's recommended interval (around 100,000 miles). Failure to do so will result in catastrophic engine damage if the belt breaks. The water pump is typically replaced at the same time as it is driven by the timing belt.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used valve body assembly from a low-mileage donor can be a cost-effective option if the original is confirmed to have mechanical damage like cracked bores. However, for the electronic components, new is strongly preferred.

Donor-vehicle mileage cap: roughly under 75000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Verify the donor vehicle's mileage and history if possible.
• Inspect the 13-pin connector socket on the used part for any signs of cracks or damage.
• Look for a date stamp on the conductor plate; newer revisions are generally more reliable.
• Avoid parts from vehicles that show signs of transmission overheating (burnt fluid, discolored case).

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

• Transmission Conductor Plate: While aftermarket options exist, OEM/OES (Original Equipment Supplier) parts from brands like Mopar or Siemens/VDO are recommended for reliability. Some aftermarket plates have higher failure rates.

Aftermarket brands forum-validated for this vehicle:

• Sonnax (For valve body repair kits and upgraded components)
• URO Parts (For the electrical connector adapter plug)
• Febi Bilstein (For the electrical connector adapter plug)

Brands owners have reported issues with on this vehicle:

• Unbranded, no-name conductor plates from online marketplaces are a significant gamble and often have high out-of-box failure rates or cause intermittent issues.

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 — Transmission Control System Malfunction. This is a generic code that indicates the TCM has stored a specific fault, such as P0750. It almost always appears alongside any transmission-specific code.
• P0755 — Shift Solenoid 'B' Malfunction. This code is often related because all shift solenoids are part of the conductor plate assembly. A failure of the plate's internal traces or a fluid-contaminated main connector can affect multiple solenoids at once.
• P0760 — Shift Solenoid 'C' Malfunction. Like P0755, this code points to another solenoid in the same assembly. A cracked conductor plate, a common cause for P0750, can easily cause faults in other solenoid circuits.
• P0715 — Input/Turbine Speed Sensor Circuit Malfunction. The speed sensors are physically integrated into the conductor plate on the NAG1 transmission. A failure of the conductor plate, a primary cause for P0750, will often trigger speed sensor codes as well.
• P0720 — Output Speed Sensor Circuit Malfunction. This is related for the same reason as P0715; the output speed sensor is also part of the conductor plate assembly that is a common failure point.

Frequently Asked Questions