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Does A Transmission Module Needs to Be Reset?
The transmission control unit, or TCU, will be programmed with the new gear ratios to help in resetting the adaptive memory in the transmission. This is wired to the TCU to automatically pre-select a particular gear and shift according to the driver’s inputs.
They make TCU part of a car’s central processing unit, and you would not need to reprogram it if you were to change transmissions.
However, the transmission control unit of your car (that includes the TCU) is not only used with the automatic gear-selecting mechanism; it is also responsible for monitoring the car’s speed.
The TCU is programmed to look at how fast your car is going and adjust its horsepower and torque accordingly.
If you get stuck in reverse, your car slows down.
The programming in the TCU will look to see if the car is moving backward, automatically decreasing your engine power and reducing gear shifting so that the sudden drop in engine power does not hurt you.
As you can see, it’s essential that a car properly calibrate its engine power and control gear shifting according to how fast it’s going.
Therefore, you must reprogram your car’s transmission before switching out transmission types. Modern transmissions are not programmable, so you must reprogram the computer should you make a change.
Does Disconnecting Battery Reset ECU?
A car ECU is a computer chip you install to control the engine. It contains hundreds of sensors, which collect information about the engine’s running conditions, and then it computes an optimum strategy for the engine to follow.
In cars without an onboard computer, the driver can use a hand-held device called a Scan Tool to check if their car needs repairs. You can also use ECU to tint windows and automatically apply brakes.
It depends on the car’s age and the type of ECU you use.
In some old cars, disconnecting the battery may cause the ECU to reset and lose its programming, requiring a dealer-level scan tool to reprogram it.
Other cars with older ECU’s may still require this reset and reprogramming when you disconnect the battery.
The car’s age and type of ECU also affect how often you will need a battery disconnect for your car to pass emission testing without causing any problems.
You will often have no problems, but reset the ECU even when it seems optional.
Some cars require disconnecting the battery while you are driving the car to reset the ECU, yet, some only require it when the one-month inspection comes around.
Ensure you read the owner’s handbook to determine what your car requires.
If the car’s age and services performed on the ECU indicate that you need to reset the ECU, remove the terminal cable from the battery. After disconnecting it:
- Wait for 5 minutes before replacing it.
- Once you replace it and start your engine, turn off your ignition once you have reached a complete stop. You may have to re-enter your security codes after doing this.
- After starting the car, start driving and check to see if your security codes are working. You may have to restart your car a few times before you can get them to work.
How Do I Reset My ECU After I Disconnect the Battery?
1. Turn off the ignition switch, and disconnect the battery.
2. Make sure the car is on a level surface and that you have working floor jacks.
3. Raise one of the front wheels off its axle until it contacts the ground, ensuring that both rims are at their respective hubs so you won’t damage them when putting them back on later.
You can do this by using jack stands, ramps, or a jack supported by some wood blocks to turn one wheel off each side of an axle.
Once both wheels are off the ground and support, leave the car in gear, turn the ignition switch to ‘on,’ and crank the engine until it stalls.
Allow the engine to stall completely before removing power from it.
4. Now that both front wheels are off their respective hubs, you can lower them back down on their axles and remove them from your jack stands or ramps.
5. Go back under your car with a flashlight, and identify where you can locate your battery. You must locate it on the alternator, in front of the driveshaft, or behind your rear axle.
It will look like a flat plate about 6 to 8 inches by 4 to 6 inches. Touching it will turn it on and off. Ensure you can’t see (or touch) your fuel pump or lines when you get under the car!
6. Carefully loosen your alternator bolts and slide them out from under the car. You may need to take a torch to the alternator if it has been sitting for some time.
Install the replacement battery and reconnect your battery cables.
7. Hook up your battery cables, check your ground connection, and put everything back together in reverse order of disassembly.
What Happens to The Car Computer When the Battery Is Disconnected?
|System Reset||A computer system often ‘resets’ when the battery is disconnected. Some cars have a backup battery that keeps the car operational for a short period.|
Some simple car computers may not include a backup battery, so it may be necessary to jump-start the car before driving.
|Radio/CD||If you connect an audio device, it will likely turn off. This is typical in many car stereos and CD players.|
|Ignition||If you connect an ignition switch, the engine may not start. This applies to most vehicles but is more common in older cars and trucks (due to weaker magnets). |
Most newer cars have strong magnets in their switches that allow you to start the car even after the battery disconnects.
|Power Windows||Depending on the type of power window motor, it may continue to operate even after the battery is disconnected. |
Older power window motors in cars and trucks may not work at all. Newer motors may work with a loss of power.
|Accessory Items||Many cars have smaller devices that you don’t connect directly to the battery, such as cruise control and alarm systems. Disconnecting the battery may cause these devices to stop working.|
|Computer Memory||If the car’s computer has a memory backup, it will save, and you can access it once you reconnect the battery and start the car. |
This type of memory is rare in cars but standard in industrial equipment such as factory robots. If no backup exists, you will lose all computer data upon disconnection of the battery.
How Do I Manually Reset My Car Computer?
Start by disconnecting the battery, which will clear the codes on most modern cars. Once you do this, turn the ignition key more than five times in 15 seconds. This will automatically engage the starter system and crank up the engine.
If your airbags deploy while at a stop before you crank and attempt to start, do not continue because of safety reasons.
The airbags may have deployed due to an electrical or computer fault that could cause an explosion or fire from starting. Take your car to your dealership for help because you must first reset the airbag warning light.
If you’re a DIY-type, you can try to clear the fault code that set off the airbag as follows:
1. Turn the ignition switch ON (as far as you can go without starting the engine) but don’t crank or start the engine and shut it OFF immediately.
Please wait at least five seconds before switching it ON again. Repeat this process.
2. With the engine OFF, turn the ignition switch to ON and complete cranking, starting the engine.
3. The service engine soon light should now be on. Let the vehicle run at idle speed for two minutes while observing it. If the light doesn’t go out, step on the brake pedal with your foot to let it know that you’re still there.
4. Turn off your car’s engine after two minutes and wait 15 seconds before restarting it.
5. Repeat steps 3- 4 until the service engine light soon turns off either on its own or after three repetitions.
6. Now do the same thing with the airbag warning light but observe that it should be off after three repetitions of steps 2 and 3.
7. Start your car and drive around for a few minutes. If the service engine soon light turns on, stop driving immediately and have your car looked at by your dealership.
What Are the Symptoms of a Bad ECM?
|Your ‘Check Engine Light’ Is On||If you have a check engine light ON, you will likely need to check your EC.|
Leaks in the intake manifold or exhaust system can trigger light and diagnostic errors with air filter sensors, catalytic converters, oxygen sensors, and emission control devices.
In some rare cases, a bad ECM might not throw any lights but will drastically lower fuel efficiency or cause other drastic changes to your car.
|Your Car Is Sputtering or Jerking||If your engine is sputtering or jerking, you may be experiencing misfires, which can be caused by faulty spark plugs, ignition coils, or a bad ECM.|
|Your Car Is Smoking||Smoke can indicate something burning in your engine that shouldn’t be, like oil or coolant. |
The problem is often a bad ECM, which would cause the burning smell in addition to misfiring.
|The Engine Stops at Acceleration Bumps Or on Hills||If your car’s engine stops when you take off on a hill or hit a bump, it could indicate an overheated catalytic converter.|
|Your Engine Runs Rough||Engines that run rough often show advanced wear in your transmission and driveshaft. A bad ECM can also cause this problem.|
|It Shuts Off During Hard Acceleration||If your car shuts off while accelerating hard, it could be due to a bad ECM.|
How Much Does It Cost to Reset An ECU?
I’ve found that the cost of an ECU reset can depend on many factors. Generally, it’s $300 to $750 depending on your car’s specific make and model.
But some service centers have reported that it can be as low as $100 or as high as $1,200 on rare occasions.
You will also need to pay for labor if you go through a dealership (though many independent shops are happy to do this for around $30) or $25 if you do it yourself.
A typical factory-refurbished ECU can cost anywhere from $500 to $1,200 depending on the year of your car, but sometimes they’re so hard to come by that dealerships will charge upwards of $2,000 for a new one.
A brand-new ECU can cost upwards of $3,000 from a dealership or up to $5,000 from an independent shop or online retailer.
I’ve found that independent shops are more willing to do this for less money than a dealership, and many can be found for as little as $30. A simple Internet search will help you find one near you.
Will Disconnecting the Battery Reset Limp Mode?
Yes! It should reset to limp mode if you disconnect your battery and reconnect it. This is how it works:
1. Disconnect the battery when your car is in limp mode.
2. Reconnect the battery to restart the engine and reset limp mode.
3. Once your car starts, continue driving it normally while the engine is running to power up the battery’s alternator again
This may only sometimes work on all cars, but it should help you get back on track! At first, you will lose power individually and then gradually gain range until everything returns online again.
In some cases disconnecting the battery won’t reset limp mode. If this happens, you will have to jump-start your car and drive to a charging station.
Just like starting the car with the battery disconnected, you should drive it to full charge once it starts.
In some cases, you require an additional step. To reset limp mode, you will have to do the following:
- Disconnect the battery when your car is in limp mode.
- Wait a few minutes for the engine to die, then reconnect the battery.
- Wait for the engine to start and drive it until everything is online again.
You can do this multiple times until the car is fully functional.
Will The Battery Drain If Only the Positive Terminal Is Connected?
No! You will only drain the car battery if you connect the positive terminal with the negative terminal.
This is because automotive batteries are composed of six cells, and each ends in a post with a connector that connects to the battery’s cable assembly.
These posts have insulators, or insulating spacers, between them to prevent electric arcing from one cell to another.
If you disconnect the negative terminal and connect the positive terminal without some form of grounding, you create a potential difference between the positive and negative posts.
This potential difference across the spacers discharges any current that it stores in those cells. The current cannot drain if you have nothing grounded to act as the ground or harmful contact.
When replacing or repairing a battery or alternator, it is essential to thoroughly check all damaged or loose connections before touching anything else.
A discharged automotive battery is hazardous and must be handled with care to avoid the risk of serious injury.
If this is not the case, say you had hooked up a jumper cable straight to the positive terminal of your car battery, then there would be no reason for this warning.
But in reality, you wouldn’t do that because the first step would be to check that your connections were tight on both ends. This could be a hazard if they weren’t.
What Triggers Limp Mode? And How to Fix
|Triggers||How to fix|
|Faulty Engine Sensor||Test by turning off the engine and then restarting it.|
If limp mode is triggered again, replace the engine sensor
|Loose Or Broken Vacuum Hose||Reconnect hose, tighten screws on connection point, replace vacuum pump (if applicable)|
|Wiring To Low Fluid Levels||Check fluid levels. If the fluid level is low, refill fully. If the fluid level is high, check the flushing pump and restrictor in the tank.|
|Gearbox Malfunction||Check for easy-to-access oil leakages in the gearbox -obtain a toothpick and check for oil leaks|
Inspect gearbox parts such as clutch components, thrust bearings, and impeller
If possible, request assistance from an ASE Certified mechanic or technician.
|Clutch Malfunction||Remove the engine to check the flywheel and clutch components.|
Check clutch operation using a new mixture of kerosene, carburetor cleaner, or water
If the system is dripping or leaking, try removing the impeller
|Clutch Pump Malfunction||Disconnect the battery and remove the spark plug from Gear Box. After a few seconds, turn on the engine. |
Wait until you hear clattering noise from the flywheel/clutch mechanism. Remove the Flywheel/Clutch. Replacing the Gear Box should do it
|Water Damage||Try replacing a few components. If the engine is flooding, replace it.|
|Defective Fuel injector/Injectors||Test for 30min using the fresh mixture for injectors -Refill fuel to full or near full.|
If the problem persists, replace a few parts, and the engine should run again
Your car’s ECU is an integral part of your vehicle’s central processing unit, helping to control all the car’s electrical and mechanical parts, including the transmission.
It is programmed to look at how fast your vehicle is going and adjust its horsepower accordingly. If you reprogram the computer system by switching transmissions, you must reprogram it again.