Can Low Transmission Fluid Cause Overdrive Light to Flash?

Can Low Transmission Fluid Cause Overdrive Light to Flash?

If you were out driving around and suddenly the overdrive light started flashing, don’t panic. This can be a bit of a scary sight, but most of the time a flashing O/D light is a simple fix. And if suspect low tranny fluid, and wondering can low transmission fluid cause overdrive light to flash, the answer is yes.

Low transmission fluid will cause the overdrive light to flash. Since the transmission overdrive is controlled by a solenoid, it’s activated by fluid pressure. When fluid pressure is low, the solenoid will be unable to activate the overdrive gear and flash the overdrive light as a warning.

Truth is, transmission fluid is essential to the proper functioning of your car’s overdrive system. Without enough fluid, the system can’t work properly and will cause the overdrive light to flash.

However less likely, there are other potential causes for that flashing overdrive light as well. Electrical problems can cause a flashing overdrive light too. Check for a loose connection from the wires to the transmission.

If you find a loose connection, make sure to tighten it up so that your transmission can function properly.

Also, check to see if any wires going to the transmission are frayed or damaged in any way. If they are, then that may be cause of your flashing overdrive light problems.

In this article we’ll explain how to fix a flashing overdrive light, and whether driving on low transmission fluid can cause long-term problems. We’ll also look at some of the symptoms of low transmission fluid, and offer some tips for how to fix that problem too.

So, if you’ve been seeing this flashing O/D light lately, keep reading!

How Does Automatic Overdrive Work?

So how does automatic overdrive work? Automatic overdrive is simply an extra gear that’s added to the transmission. This gear is designed to reduce engine RPMs at higher speeds, which results in better fuel economy.

Getting a little more technical, here’s how an automatic transmission works.

An input shaft of your automatic transmission is connected to the engine through a torque converter. That torque convertor is filled with transmission fluid.

The torque converter allows the engine to run freely at low RPMs while the transmission is in gear. For example, this keeps your car from stalling when at a stop light. As you accelerate, the torque converter transfers power and the transmission responds in first gear.

As you speed up, and the transmission shifts from low gear to higher gears, very similar to how you change gears on a bicycle. Each gear is matched to the power the engine needs to produce for any given speed.

With each gear, the ratio of the speed of your engine to the speed of the transmission output changes. Once your vehicle reaches a consistent speed, the overdrive gear kicks in. This helps your engine run more smoothly and efficiently, save gas, and reduce engine wear and tear.

Driving on Low Transmission Fluid a Good Idea?

You can drive a car with low transmission, but it’s not advisable. However, if your overdrive light is flashing, then it’s a warning something isn’t functioning properly. Proper transmission fluid levels are key to maintaining the solenoids. If the fluid dips too low, it can cause the solenoids to malfunction causing the O/D light to flash.

Simply put, transmission fluid is vital for keeping your car’s essential transmission components functioning properly. This includes the torque converter, hydraulic pump, solenoids, planetary gears and clutches.

Without enough fluid, your car’s transmission can overheat and break down. So, if you’re low on transmission fluid, be sure to top it off. Otherwise, you could end up needing a costly transmission repair.

How to Fix Overdrive Light Flashing

First, check the fluid level. To do this, follow these simple instructions below.

Time needed: 35 minutes

How to check and add transmission fluid:

  1. Start by parking the car on level ground

  2. Pull out the dipstick and wipe it clean

  3. Next, put it back down that same tube slowly, and then pull it back out

  4. Check the fluid level and take note of how high the fluid comes up on the dipstick hash marks. See if the fluid level is at the “full”, “low” or “fill” marks on the dipstick

  5. If the fluid only comes up to the “low” or “fill” marks, your transmission needs more fluid

  6. Insert long funnel into automatic transmission fluid dipstick hole

  7. Check the owners manual for proper fluid for your vehicle

  8. Carefully add automatic transmission fluid in small increments until it reaches the “full” mark on the dipstick

  9. Replace the dipstick and take the car out for a test drive

  10. Recheck fluid level again, and top off if needed

How Much Transmission Fluid Should I Add?

Usually, when you check the transmission fluid level, it should be at the crosshatch mark on the dipstick.
If it’s below that, you’ll want to add some until it reaches that point. If it’s above that, no worries! You don’t need to add any.

After you’ve filled the tranny fluid, if the overdrive light continues to flash, it’s time to seek out a mechanic. You might have a bad solenoid.

Is Too Much Transmission Fluid Bad?

Adding too much transmission fluid can actually be harmful to your car. The effects of overfilling the tranny fluid causes hard shifting, gear slippage and leaky seals. Excessive pressure build-up from the fluid can also cause premature failure to internal components, leading to transmission failure.

O/D Light Flashing Even When Tranny Fluid is Full

If the transmission fluid is full, then make an appointment to have your tranny flushed. Make sure they also change out the tranny pan filter as well.

If the flashing overdrive light continues, then a solenoid might of been damaged. Replace all control solenoids until the flashing O/D light goes away.

Also, it’s worth checking that all wire connections to the transmission are tight, and no wires have been damaged.

What Are The Symptoms of Low Transmission Fluid?

If you feel your car is having trouble shifting gears or if the gears seem to slip, it could be a sign that your transmission fluid is low. You might also notice that your car is experiencing slow gear engagement as well.

Another telltale symptom of low transmission fluid is a burning smell inside or outside the vehicle.

Perhaps the most obvious symptom of low transmission fluid is a flashing overdrive light.

What Does the O/D Off Light Mean?

If the O/D light comes on and stays on, it means that the overdrive in your car has been disabled. The transmission cannot shift to the highest gear to maintain a steady speed while driving.

The higher gear ratio is what allows the engine to run at a lower revolutions per minute (RPM). This can save fuel and wear on the engine.

So what does o/d off mean then? Simply put, the transmission cannot go into it’s highest cruising gear.

How Long Can You Drive With Low Transmission Fluid and Flashing O/D Light?

You can drive a car with low transmission fluid for 10 to 15 miles. However, it’s not advisable to drive for long distances beyond 15 miles with low transmission fluid. Doing so could damage your car’s transmission.

Remember, that flashing overdrive light is a warning something isn’t right.

How Can Low Transmission Fluid be Prevented?

Regular maintenance is the key to preventing low transmission fluid. Checking your transmission fluid levels regularly and topping off as needed is the best way to keep your transmission healthy.

Final Thoughts: Can Low Transmission Fluid Cause Overdrive Light to Flash

Transmission fluid is essential to the proper functioning of your car’s overdrive system. Low transmission fluid can cause all sorts of problems, including the dreaded overdrive light flashing. Make sure you keep an eye on your transmission fluid levels and top off as needed to avoid any costly (or dangerous) repairs down the road.

Also keep in mind that, driving with the overdrive light flashing for more than 15 miles can cause damage. If you’re driving and you see the overdrive light flashing, check the tranny fluid as soon as possible.

Continuing to drive with the overdrive light flashing could ultimately cause damage to your car.

Hopefully this articles answers the question, can low transmission fluid cause overdrive light to flash. Have you dealt with a flashing O/D light before? Share your story in the comments section below.

Last Updated on January 26, 2023

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