The situation when you approach the car, turn the key in the ignition lock, and in response - silence or tense hum of the starter, can knock out any driver. It is especially alarming if the vehicle is equipped with an automatic transmission, where the electronics and mechanics are intertwined in a complex assembly. Owners often wonder why the machine does not start, forgetting that the problem can lie not only in the engine itself, but also in the transmission locks.
Before panicking and calling a tow truck, it is necessary to conduct a primary diagnosis. Modern security systems electrician They can block the launch at the slightest deviation from the norm. This can be a discharged battery, a failure in the work of the immobilizer or a banal attempt to start the engine when the selector DISTRIBUTION positioned Drive or Parking with a backlash. Understanding the nature of the sound that the starter makes, or its complete silence, is the first step to successfully solving the problem.
In this article, we will discuss in detail the main reasons for the engine failure to start, paying special attention to the specifics of automatic transmissions. We will consider both simple operational errors and complex technical malfunctions that require the intervention of specialists. Competent approach to diagnosis will help to save time and money, avoiding unnecessary spending on services of service centers.
Problems with electricity and battery
The most common, but most common reason why a car refuses to start is because of the power supply. If the starter is silent or only makes a quiet click, in 80% of cases the discharged one is to blame. battery. In winter or after a long downtime, the battery capacity drops, and the current becomes insufficient to turn the crankshaft. Even if the headlights are on, this does not guarantee that the starting current is enough to start the engine.
However, it can be not only in charge, but also in contacts. Oxidized terminals create high resistance, which is why the voltage on the starter simply does not reach. It is necessary to visually examine the battery conclusions: the presence of a white or greenish plaque indicates poor contact. It is also worth checking the reliability of attaching the mass wires to the body and engine, since oxidation These are often ignored in the diagnosis.
⚠️ Warning: Attempting to light up a car with a completely frozen battery can cause it to explode or fail electronics. If the electrolyte inside the battery has turned into ice, charging or starting from another car is prohibited until it is completely thawed.
Another hidden enemy is the starter himself. If the battery is in good working order and the terminals are clean, but when you turn the key, a loud click is heard, and there is no rotation, it may have jammed the bendix or burned the winding of the traction relay. In such cases, sometimes it helps to gently tap the starter body, but this is a temporary measure. For vehicles with automatic-box The status of contacts in the launch lock chain is critical, which we will discuss below.
Blocking the launch by the automatic transmission selector
A unique feature of cars with automatic transmission is the presence of a security system that prohibits starting the engine if the selector is not in the parking position. This is the responsibility of the position sensor of the gear lever, often called neutral-starter. If the electronics "think" the machine is in gear, it breaks the starter's power circuit to prevent the car from jerking.
It often happens that the lever is visually in position. PBut because of the stretching of the cable or the failure of the sensor settings, the contact does not close. In this case, the car does not start, although everything looks good. Try to move the selector to the position N (Neutral) and try to start the engine. If the neutral launch was successful, then the problem is in the desynchronization of the position of the lever and sensor.
- 🔧 Check whether the key is tightly inserted into the ignition lock, as some systems read the position of the selector only when the fully rotated key.
- 🔧 Swing the gear lever from side to side, trying to "catch" the position at which the start indicator will light up.
- 🔧 Inspect the wiring connector going to the gearbox: oxidation or a wire break can simulate the gear on.
In some modern models robotic boxes or variators may require a deeper dive into settings through a diagnostic scanner. If mechanical movement of the lever does not help, perhaps the tip itself has failed or the fuse responsible for the starter lock chain has burned out. This is a classic example of how electronics Protects the driver from his own mistakes, but creates problems when the driver fails.
If the machine does not start in position P but starts in position N, don’t ignore this. Sooner or later, you will forget to switch, and the car may burst from the spot, which will lead to an accident.
Failures in the ignition and fuel supply system
If the starter cheerfully turns the engine, but “snatching” does not occur, then the problem lies in the absence of spark or fuel. In gasoline engines with distributed-injection A frequent cause is the failure of the ignition coil or candles. This is especially true in wet weather, when high-voltage wires break through. The absence of a spark in the cylinders makes it impossible to start, no matter how much the starter spins.
The fuel system is more complicated. If after turning the key you do not hear the characteristic hum of the pump, which usually lasts 2-3 seconds, then the pump does not create pressure in the ramp. This can be caused by a burnt pump relay, a clogged filter, or the death of the motor itself. Without a certain amount of pressure. nozzle They can't spray the fuel, and the mixture won't ignite.
| Symptoms. | Probable cause | Action. |
|---|---|---|
| Starter spins, no pump sound | Fuel or relay of the gas pump burned | Check the fuse block |
| The engine "captures", but stalls | Contaminated throttle or idle regulator | Flush the throttle knot |
| Unstable launch into the cold | Low octane fuel or water in the tank | Pour the sludge, add the additive |
| Launch only with an open throttle | Failure of the throttle position sensor | Scanner diagnostics |
The system deserves special attention. Common Rail in diesel engines. There the pressure must be enormous, and the slightest velocity of the system or malfunction of the TNVD lead to the impossibility of starting. Unlike gasoline engines, diesel will not start if the candles are not warmed up, especially in the cold season.
Failures in the work of the immobilizer and electronics
A modern car is a computer on wheels, and often the reason why the machine does not start is because of software failure or protection against theft. The immobilizer reads the chip in the key and gives permission to launch. If the antenna in the ignition lock is faulty, or the chip in the key has demagnetized, the engine will not start, although the starter may be running. On the dashboard in such cases, the indicator of the key or lock often flashes.
Electronic control unit (E-control unit)EBOU) may also go into “emergency mode” or freeze. This happens after voltage surges, for example, when "lighting" or disconnecting the terminals on the working engine. In this state, the car’s brains may block the supply of spark or fuel for safety reasons. Rebooting the system sometimes helps: it is enough to remove the battery's negative terminal for 10-15 minutes.
How to Reset Errors Without a Scanner?
Remove the negative terminal from the battery. Wait 15 minutes. Press the brake pedal 5-10 times to discharge the residual voltage in the chains. Put the terminal back on. Start the engine and let work for idle 5 minutes without loading.
It is important to note that some systems require the key to be synchronized with the control unit after the battery is replaced in the key fob. If you changed the battery in the key and the machine stopped responding, the frequency or code may have gone astray. In such cases, a spare key helps, if it is available. Ignoring the problems with the immobilizer can lead to a complete shutdown of the start when the car turns into a real object.
Mechanical problems of the engine
When all electrical systems are in good working order, fuel is available, spark is present, but the engine is silent or makes unnatural sounds, it can be serious mechanical damage. The most terrible reason is the break of the belt of the GRM. In this case, the camshaft ceases to synchronize the valve with the pistons. The engine rotates the starter too easily, without the characteristic compression resistance, and air can blow from the exhaust pipe.
Another problem is the engine jamming. If the engine is heated and stopped, and after a while the starter can not turn it and heard a dull knock or crack, perhaps twisted the crankshaft inserts or jammed the pistons. Attempts to start such an engine "from a pusher" or in tow are strictly prohibited - this will finish the knot completely.
- 🔩 Check the oil level: its absence could have led to dry friction and jamming.
- 🔩 Listen to the sound of rotation: if the starter barely spins a serviceable battery, perhaps the engine "captured".
- 🔩 Check the belt of the timing: if it is torn or cut teeth, start the engine can not.
It is also worth mentioning the problem with compression. Wear of piston rings or burn valves lead to a drop in compression below the critical level. The fuel mixture is not compressed to the desired state and does not ignite. Diagnosis of compression is carried out by a special device - a compressometer, and this is a mandatory procedure when searching for the cause of a difficult start.
☑️ Primary Diagnostics of Launch Failure
Climate and operating conditions
External factors often become a trigger for the manifestation of hidden malfunctions. In severe frosts, the oil in the engine and box thickens, increasing the resistance to rotation. The starter lacks the power to overcome this threshold and the car won't start. For automatic transmission Cold is also dangerous: liquid ATF It becomes viscous, which can create additional resistance, although it affects the engine start less directly than thick engine oil.
High humidity and dampness contribute to the formation of condensation in the exhaust system and on the contacts. The ice crust in the muffler can block the exhaust gases, which is why the engine will stall immediately after start-up or not start at all. In such cases, it is recommended to first clean the exhaust system before trying to spin the starter.
⚠️ Warning: Long-term work of the starter (more than 10-15 seconds) without interruption leads to its overheating and melting of the wiring. Take pauses between launch attempts for at least 30-60 seconds to allow the battery and starter to cool.
The quality of the fuel also plays a critical role. In winter, gasoline may contain water that freezes in fuel lines or filters, blocking the supply of gasoline. The use of seasonal additives-dehydrators and refueling at proven gas stations helps to avoid a situation where the car is standing because of a couple of liters of low-quality fuel.
Frequently Asked Questions (FAQ)
Why doesn’t the car start if the battery is new and the starter is spinning?
If the starter is working properly, but the engine does not start, the problem lies in the ignition system (no spark) or fuel supply (no pressure in the ramp). It is also possible that there is no signal from the crankshaft position sensor, without which the ECU will not give a command to inject.
Could a faulty automatic transmission be the reason why the starter is not spinning?
Yeah, maybe. If the position sensor of the gear lever (selector) is defective or knocked down, it does not signal to the control unit that the neutral or parking is turned on. Electronics block the starter for safety purposes.
What if the car starts and immediately stops?
This may indicate a malfunction of the idle regulator, an unaccounted air pump, a contaminated throttle, or problems with the immobilizer. Computer diagnostics is required to read error codes.
How do I know if the gas pump has burned?
When the ignition is turned on (before the starter is launched), a quiet hum should be heard from the gas tank area. If there is no sound, and the safety of the pump is intact, most likely, the pump itself or its relay is defective.
Diagnosis always start with a simple one: checking the battery charge, the position of the automatic transmission selector and the availability of fuel. 70% of the problems are solved at this stage.