December 23, 2023

Acura RL (2006-2012) Rough Shift? Let us Help.

Acura RL D4 rough shift engine light As a long-time owner of an Acura RL I’ve experienced not only the engine light, but also the D4 blinking and the rough shift that follows. The RL, while a reliable vehicle, isn’t immune to issues, especially concerning its transmission system.  I’ll share my experience in diagnosing and fixing this common transmission problem.

Engine light or long start?

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Symptoms and Troubleshooting your Acura RL

When your Acura RL has rough shifting you need to figure out if it’s mechanical or related to a sensor or the transmission fluid. Mechanical failures typically cause persistent rough shifting. On the other hand, if your transmission performs normally aside from the warning lights, you might be dealing with a faulty sensor or dirty transmission fluid.

  1. Rough Shifting: Most common, where the transmission doesn’t shift smoothly between gears.
  2. Blinking “D4” Light and Check Engine Light: These lights often go together.
  3. OBD Codes: The codes P0700, P0730, P0740, P0780, P1768, and P1768 are indicators of transmission problems. Other OBD codes include P0715, P0720, and P1750.

Rough Shifting and Warning Lights

One of the most common symptoms I’ve noticed is rough shifting. This issue is often accompanied by the blinking of the “D4” light and the illumination of the check engine light. This is a clear signal that the transmission needs attention.

OBD Codes

The On-Board Diagnostics (OBD) system in your RL might have multiple codes. Some common ones include P0700, P0730, P0740, P0780, and P1768. Each code points to a specific transmission problem.  See all the OBD codes here.

  • P0700: Transmission Control System Malfunction
  • P0730: Incorrect Gear Ratio
  • P0740: Torque Converter Clutch Circuit Malfunction
  • P0780: Shift Malfunction
  • P1768: Performance / Normal / Winter Mode Input Malfunction

Additional OBD Codes Related to Transmission Issues

  • P0715: Input/Turbine Speed Sensor Circuit Malfunction
  • P0720: Output Speed Sensor Circuit Malfunction
  • P0741: Torque Converter Clutch Circuit Performance or Stuck Off
  • P0750: Shift Solenoid A Malfunction

Mechanical Failure vs. Sensor or Fluid Issues

Let’s determine whether the issue is mechanical or related to a sensor or dirty fluid.  If the transmission shifts roughly, it’s likely a mechanical failure. If it performs normally but still shows warning signs, a faulty sensor or dirty fluid might be the culprits.  Also, by changing the transmission fluid, a complete mechanical failure may be delayed.

DIY: Replacing Transmission Fluid in Acura RL

Tools and Materials Needed

  • Transmission Fluid (specific to Acura RL)
  • Drain Pan
  • Socket Wrench
  • New Transmission Filter (optional)
  • Gloves and Safety Glasses

Steps

  1. Locate the Transmission Fluid Dipstick: Check your RL manual for the exact location.
  2. Warm Up the Car: Run the engine for a few minutes.
  3. Position the Drain Pan: Place it under the transmission drain plug.
  4. Remove the Drain Plug: Use the socket wrench to remove it and drain the old fluid.
  5. Replace the Transmission Filter (Optional): This is a good practice when changing fluid.
  6. Refill with New Fluid: Use the dipstick hole and follow the manual for the correct amount.
  7. Check for Leaks: Start the engine and look for any leaks.
  8. Dispose of Old Fluid Properly: Take it to a recycling center or auto shop.

Final Thoughts

Understanding the symptoms and troubleshooting, particularly with an engine light, can make a difference. Regular maintenance, like changing transmission fluid helps prolong the life of your vehicle. Always consult a professional mechanic if you’re unsure or if the problem persists.