The easiest way to perform an ECU reset is by removing the fuse from the fuse box. It is a very simple process, and all you have to do is pull out the car key, remove the fuse from the fuse box, and then put it back after about 15 to 20 seconds. Doing this clears any long-term memory stored in the car's ECU.
On a newer model car the ECU/ECM controls everything ignition related AT LEAST. Timing, ignition, air. When the fuse blows, the engine control unit/module loses power and is unable to control the ignition process, the throttle (drive by wire) shuts and fuel ceases to be commanded to move. No spark is commanded to fire.
Turning back the screw and erasing the codes is the same resetting the ecu.
Like desktop computers and most other electronics, disconnecting the battery cable for a short period will not fully reset your ECU due to the residual power remaining in the circuits.
It really depends on the ECU, the car itself, and what year car it is. Also, it depends on what is being relearned. Some things, like short term fuel trims can be learned in as little as 20 miles. Other things like long term fuel trims will take longer, maybe 80 to 100 or more miles.
ECM stands for Engine Control Module, and ECU is short for Engine Control Unit. These two acronyms represent the same component and are used interchangeably.
You should expect to pay between $150 and $300 at a local repair shop or service center just to have the ECU inspected and tested.
The service "ECU reset" is used to restart the control unit (ECU). Depending on the control unit hardware and implementation, different forms of reset can be used: "Hard Reset" simulates a shutdown of the power supply. "key off on Reset" simulates the drain and turn on the ignition with the key.
Not only can you detect malfunction patterns in your vehicles, but you can also monitor driving habits or find out what could be causing your cars to break down. However, failing to clear a code after a repair could leave you second-guessing the issue or doubling your work to recheck the codes.
The ECU constant power supply is protected by a 7.5A fuse located on D1 on the ECU, not shown in the images. The 7.5A fuse should be unplugged to reset the ECU. Always check the fuse properly by using a test light or a multimeter.
If the ECM fuse keeps blowing, then there is a definite electrical short. Most of the time the short is in the ECM, but it may have a short in the wiring going to it. I usually isolate it by going through the wiring schematic and disconnecting areas of the circuit until I find the short.
ECU re-programming is not required because most repairs are done on the hardware parts and not on the software programming. Therefore, the programming of the ECU will never be altered.
The main symptoms of a faulty ECU
Well-known examples are: engine failure light (MIL light) that lights up on the instrument cluster, car that goes into emergency mode, the car shakes or when the engine no longer runs on all cylinders. It can all indicate a malfunction of the engine control unit.
Method Two: Remove the ECU Fuse
Thus, without a working ECU, a car can not get fuel to the engine, meaning it can not run.
Should you disconnect the battery when changing fuses? Yes. Always ensure to turn off your vehicle's ignition and disconnect the battery before you open or start working on a fuse box.
Switch this breaker fully to the “off” position and then switch back over to “on”. Your power will now be restored! To test, plug a few things back in and turn them on to test your new fuse or reset breaker. If everything comes back on, congratulations – you have successfully fixed the issue!
Disconnect Battery Cables
Your job is to disconnect both. However, DO NOT disconnect the positive terminal before the negative one. Doing so can cause an electrical short. Always disconnect the negative battery terminal first.
If you disconnect the positive terminal first, one slip of your wrench could send a direct short to the ground, which can be very dangerous. Its possible that you could experience a huge spark, the wrench could melt in your hand or the battery could even explode!
Why you need to reset the computer: Your car's computer—the ECU—reads data from your vehicle while it's in operation, and a battery replacement disrupts this process. It needs a chance to clear error codes after a new battery is connected.