why is your check engine light on?

Your car's automatic transmission pump is vital to the proper functioning of your transmission. The pump regulates fluid pressure and distributes it through the clutches and the torque converter so that they can shift smoothly. This component runs every time the engine is running. When it's not working properly, your transmission can fail or burn out prematurely. However, you will likely get several noticeable symptoms before everything comes to a stop. 

Weird noises:

When your transmission pump is failing, you will hear strange noises. The noise you will most likely hear in this case will be a loud whining noise. Since the pump works the entire time your engine is running, you will hear this whine no matter what gear you are in, including park or neutral. It may increase or decrease with engine speed. However, if you hear this noise, then you should, at first, try changing the fluid and filter. A clogged filter can not only cause a similar noise, it can also contribute to pump damage.

Harsh shifting:

Because the transmission pump helps provide fluid pressure, and that pressure controls the gears and torque converter, your transmission won't shift as smoothly as it should. The gears will feel like they're slipping or hesitating. You will find yourself pressing on the gas and the engine will rev up before the car suddenly "catches" and you lurch forward. When changing gears while on the move, the car will shift erratically and you will feel a jerking motion. This could be a potential safety hazard in that you will lurch ahead and hit another vehicle or not be able to get out of the way or a hazard if your transmission can't get into gear.

Burning smell:

When the pump is not sending enough lubrication around to the gears, then components will begin to heat up with added friction. This means that the fluid and rubber components will also begin to burn and you will smell a distinct burning smell. Even if you don't smell anything burning while driving the car, the problem signs will show up in your fluid. When you check the fluid, it will appear darker than usual or even brown. There may be a distinct "burnt" smell to it as well.

One final symptom is that your check engine light will turn on, but this does not always happen, especially when the problem hasn't reached a critical point. It's important to pay attention to the above symptoms as none of these are normal and may indicate potentially serious problems. However, it is fixable and damage can be kept minimal if caught early. Be sure to have your automatic transmission checked at a transmission shop like B G & S Transmissions at recommended intervals before problems happen.