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.
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.
Can a car run without an ECU? While a modern car may be drivable with a faulty or defective ECU, it will be impossible to drive one without an ECU at all. For instance, as a car's ECU will control the car's electronic fuel injection system, the engine won't be able to run if it's missing this component.
If your vehicle fails to start for no apparent reason, this is also a good indicator that there may be a problem with the ECU. If you check the car battery, starter and other common electrical components, and the vehicle still does not start, a faulty engine control unit should be the next logical thing to consider.
The ECU has the job of controlling the fuel injection, ignition and ancillaries of the engine using digitally stored equations and numeric tables, rather than by analogue means.
Blown fuse – Sometimes the simplest explanation is the best one. A blown fuse in the starter circuit could be the cause of a no-start problem. Broken or corroded wiring – Damaged or dirty wires to the battery or to the starter solenoid (or wires that are loose) can prevent sufficient power from reaching the starter.
Why won't my car start but I have power? If you attempt to start up your car but the engine won't turn over and the dashboard lights up, then you most likely have an issue with your battery. You could have a damaged or corroded battery terminal, which is stopping the engine from starting up when you fully turn the key.
If your vehicle won't start, it's usually caused by a dying or dead battery, loose or corroded connection cables, a bad alternator or an issue with the starter. It can be hard to determine if you're dealing with a battery or an alternator problem.
If your ECU controls the anti-theft system, disconnecting the battery may lock you out of your car. 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.
Depending on the application and the controller hardware, there are several ways to perform bypassing. One way is to use bypass hooks or service calls to jump from the controller to the real-time system. Another method is to change values in the memory (RAM) to overwrite specific outputs of the functions.
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. In short, the engine dies and the car goes nowhere.
It depends on the car's age and type of ECU used. On some older cars, disconnecting the battery will reset the system but in most new cars it does nothing, except potentially reset the clock and radio station presets.
Connected to the battery is the alternator, which works to generate power for your vehicle's electrical components. When you have a brand-new battery but still can't start the car, the alternator might be the issue. Cold and damp climates may increase wear on an alternator, causing it to fail.
Bad Sensors
One common culprit for this problem is the crankshaft position sensor, which measures the position and speed of the crankshaft. The computer uses the information from this sensor to know when to fire the spark plugs. If the sensor isn't working, the spark plugs won't fire, keeping the engine from starting.
It might be a battery or alternator problem.
If the source of the clicking is electrical, the starter (a small motor energized by the battery that gets the engine running) doesn't have enough juice to stay powered. So instead, it rapidly turns on and off and produces a clicking noise!
Car not starting: Another symptom of a faulty ignition relay is a no power condition. If the relay fails it will cut off power to fuel pump and ignition system, which will result in a no power, and therefore no start condition.
If the fuse to the ECU, ignition, etc. is blown then the car isn't going to start. It is possible the car starter won't even work.
Causes of a defective engine control unit
One of the main causes is a short circuit in the wiring or in components, which can cause them to burn out. This short circuit is often caused by external influences, such as the wrong start of the car.
Whilst you can adjust and replace the ECU in a vehicle that is predates 2001, you may have difficulty with newer cars. Many of these have complex computer systems and you will have to take them into an authorised dealer to have reconfiguration work performed under the hood.