Troubleshooting Transmission Issues in Acura CL (1997-2003)

As a long-time owner of an Acura CL, I’ve experienced not only the engine light, but also the D4 blinking and the rough shift that follows.  I’ll share my experience in diagnosing and fixing this common transmission problem.

Check for Recalls

Symptoms and Troubleshooting your Acura CL

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. When you experience this, it’s a clear signal that your vehicle needs attention.

OBD Codes

The On-Board Diagnostics (OBD) system in your CL can generate various codes. Some common codes include P0700, P0730, P0740, P0780, and P1768. Each code points to a different aspect of the 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

Mechanical Failure vs. Sensor or Fluid Issues

Let’s determine whether the issue is mechanical or related to a sensor or dirty fluid.  If it 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, it may help the shift problems, and a complete mechanical failure may be delayed.

DIY : Replace Transmission Fluid

Tools and Materials Needed

• Jack and jack stands
• Drain pan
• New fluid (specific to Acura CL)
• Socket set
• Torque wrench
• New transmission filter (optional)
• Safety gear (gloves, goggles)

Steps

1. Prepare: Park on a level surface, engage the parking brake, and lift the car using the jack. Securely place the jack stands under the vehicle for safety.
2. Transmission Fluid Drain Plug: Locate the transmission fluid drain plug. It’s usually easily identifiable and accessible.
3. Drain: Place the drain pan under the plug, remove the plug with a socket wrench, and let the old fluid drain completely.
4. Transmission Filter (Optional): Remove the old one and install a new filter.
5. Refill: Once drained, replace the drain plug and tighten it with the torque wrench. Fill the transmission with new fluid through the dipstick tube, using a funnel to avoid spills.
6. Check Fluid Level: Start the engine, let it run for a few minutes, and then check the fluid level. Add more if necessary, ensuring you don’t overfill.
7. Disposal: Take the old fluid to a recycling center or an automotive shop that accepts used fluids.

Acura CL Additional Codes

Apart from the ones mentioned earlier, other codes relevant to transmission issues in your Acura CL include:

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

Final Thoughts

Understanding the symptoms and troubleshooting, particularly with an engine light / D4, can make a difference. Regular maintenance, like changing transmission fluid, plays a role in the life and performance of your transmission. Always consult a professional mechanic if you’re unsure or if the problem persists.