Learning All About Auto Body Restoration

Learning All About Auto Body Restoration

DIY Car Guide: Is It Your Transmission Modulator? Find Out & Fix It

Cody Wade

The transmission modulator valve helps control every shift you command, and it dispenses the right amount of fluids to take care of the transmission system. This little valve is necessary for the transmission to function properly, which you can call your transmission's command center. Sadly, this compartment--like other parts--can fail, and you should know a few symptoms and how to fix it if necessary. 

Tell Signs That You Have A Bad Modulator

The following are a few signs that your transmission modulator valve has gone bad:

--A faulty valve might alter the level of fluids in your transmission system. This could cause gear damage, which could lead to metal debris within your system. Gear damage and debris can further damage your transmission and cause an imbalance in pressure. The transmission needs specific pressure to help you shift smoothly, so you might feel shifting delays or hard shifting.

--The gears can stick or completely fail. This happens because your modular valve is simply not giving your transmission system enough lubrication. Your transmission might also overheat due to the improper lubrication.

--You might see blue smoke from the exhaust pipe when you are in park and the vehicle is warmed up. This occurs because the valve is allowing transmission fluid to run up towards the engine. This burns the fluid, causing blue-like smoke.

You can talk to your auto care specialist to help confirm your suspicions regarding some of these symptoms. 

Changing Your Own Transmission Modulator Valve

You will need the following:

  • Your owner's manual or repair guide
  • Protective accessories, like safety goggles and gloves
  • New transmission modulator valve specific to your car
  • Hydraulic floor jack
  • Jack stands
  • Your set of wrenches and your socket set


  1. Park your car in a safe place, and let it sit long enough to work on comfortably. 
  2. Put your safety goggles and gloves on.
  3. Disconnect the negative or red cable from your battery, just to be safe. 
  4. Lift the vehicle using your hydraulic floor jack. Place the stands in the appropriate areas to keep your car high enough to work on. You can remove the hydraulic jack once the jack stands are securely in place. 
  5. Look for the transmission modulator, which is usually at the end of your transmission. 
  6. Disconnect the vacuum hose leading to the valve.
  7. Remove the valve, and replace it with your new one. 
  8. Reconnect your vacuum hose to your new transmission modulator valve. 
  9. Use the hydraulic jack to lift your car off the stands. Remove the stands, and drop your vehicle down using your hydraulic jack.
  10. Start your vehicle to see if changing the valve did the trick.

As you can see, changing the modulator is not too bad and could save you some money. Remember that you can ask an auto care specialist, like the ones at Knoll Automotive Services, to take care of this issue if you feel uncomfortable with any of the aforementioned steps.


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About Me
Learning All About Auto Body Restoration

Hi guys, the name is Phyllis. I'm here to teach you all there is to know about auto body repair. I grew up watching my dad strip down cars and restore them to new with beautiful coats of paint. Between coats, I loved to see how the sanding process removed imperfections and readied the surface for more paint. I grew to love the hobby enough to try it out for myself. My journey started with bicycle frames. The frames easily hung from the ceiling to make sanding and painting a breeze. Eventually, I took my sander and sprayer to the finish of my old car to restore its beauty. You can learn about the auto body repair and restoration process by visiting my site each week. I'll share information about traditional and modern techniques, tools and parts you can use to improve the finish on any vehicle. Thanks for visiting!