A dead battery, an alternator issue, or a bad starter are the three most frequent causes of a Kia Soul not starting.
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Why won’t my car start despite being on?
A fading or dead battery, frayed or corroded connecting cables, a defective alternator, or a problem with the starter are the common culprits when a vehicle won’t start. It can be challenging to tell whether a battery or alternator issue is at hand. Here’s how to determine who the culprit is.
Bad Battery Symptoms
Consider a failing battery, a loose or corroded connection, or an electrical draw if your car cranks slowly, starts inconsistently, is harder to start on chilly mornings, or doesn’t make any sound or light up the interior when you try to start it. A low battery with terminal corrosion that is obvious is likely damaged.
If a jumpstart is successful, a battery issue is present. However, you must also determine whether it is just nearing the end of its life or whether there are more serious problems. A malfunctioning alternator may be the cause of a dead or depleted battery. The additional pull from auxiliary lights, fuses, sound systems, alarms, and other devices may also be the cause.
How can a no start issue be identified?
For a gasoline engine to start and run, it needs a spark, fuel, and compression. An organized approach will enable you to rapidly identify what is lacking and why when an engine won’t start.
Years ago, I heard a fellow technician say, “If you can’t diagnose a no-start, don’t open the hood.” That assertion suggests that no-start diagnosis has to be a fundamental technique and the starting point for understanding how the complete vehicle operates. What could be more fundamental than spark, compression, fuel, and timing?
“An essential, fundamental element or entity” is the meaning of “basic.” You’ll see that the definition omits terms like simple and easy. We often neglect the fundamentals of automotive technology because they are not always clear-cut or simple. In this article, I’ll demonstrate how to use an organized method for no-start diagnostics and explain why focusing on the essentials speeds up the process.
Identification
The diagnostic process can be sped up by quickly determining the potential causes of a no-start. Start by asking the car owner at the front desk for comprehensive and accurate information. Finding out that the owner attempted a timing belt repair over the weekend is the reason the engine won’t start could save you a lot of time and point you in the right direction for a diagnosis. The engine may have also failed to start after the body control module (BCM) was replaced, refused to start after it had been warmed up, or started normally when it was cold but not warm. Each of these symptoms is a valuable piece of information that may be used to construct a diagnostic course and carry out an effective diagnosis.
Why is this crucial? If the battery is low or dead by the time the car gets to your facility, it might not start. Now you have to decide if this is the actual issue or if the battery was discharged as a result of the customer’s persistent attempts to start the vehicle. The engine might start easily after you charge the battery. The queries now are: “Is there a current drain or was something left on? Or does it occasionally not start?” As you can see, if the wrong or insufficient information is gathered up front, a lot of time might be lost looking for the wrong condition.
Cranking
The cranking circuit is always the starting point of a no-start diagnosis, as is the case with all effective diagnostics. The battery, starter, and cables that link them make up the cranking circuit in its most basic form. Of fact, the starter relays/solenoids, ignition switch, and even the theft-deterrent system are crucial components of the starting system, but for the purposes of this discussion, let’s concentrate on the starter and battery.
Any no-start diagnostic should start with a battery test. Engine starting depends heavily on battery health, including battery voltage while cranking. If the battery voltage falls too low while cranking, the electric fuel pump may not be able to operate at its peak efficiency, which would restrict gasoline delivery. This can be misdiagnosed as a fuel pump issue. An ECM that doesn’t power up is another, less often, consequence of low battery voltage when cranking. This may lead to a lack of spark, a lack of fuel delivery, or both.
Excellent options include proper voltage and load testing, followed by a dynamic test. Monitoring the voltage and current of the starter while it is cranking is a part of dynamic testing. Many modern vehicles require a specific voltage when being cranked. Some circuits might not work without it. For instance, certain imports need 11 volts before the ECU starts working. Low fuel pump output is another frequent low voltage issue that causes a no-start due to insufficient fuel delivery.
The cranking circuit’s other end is connected to the starter. The mechanism aims for proper starting rpm. Numerous issues, such as engine or gearbox drag, insufficient voltage, or an accessory load, such as a locked alternator, might affect the starter rpm. Or the starter may be defective.
Starter voltage is frequently disregarded because starter examinations frequently entail current measurements. The voltage at the starter terminal when cranking, as opposed to the measured voltage at the battery, is the starter voltage. The circuit’s internal voltage drop may lower the startup voltage that is available.
Before banning the starting when the voltage is correct but the problem is excessive current, the source must be identified. Accessory lockup is a frequent issue on cars using serpentine belts. Any of the serpentine belt-driven accessories could be impacted, but alternator failure is the most frequent. Seized alternator bearings increase cranking resistance and cause higher-than-normal starting current consumption as a result.
When the true source of the excessive draw is found, replacing the starter before finding the source of the high starting current draw can cause complications for the service writer and leave you looking foolish. The only way to make this scenario even worse is to attribute the problem on the starter rather than the engine. When dealing with high starting current draw, you should always remove the serpentine belt and start the engine with a ratchet before finishing the examination.
Spark
It’s time to focus on the engine’s failure if the cranking circuit has passed the necessary tests. Spark, fuel, compression, and timing are the four issues that need attention. The ignition system test is typically the first and most straightforward to do. It is practical to remove a coil wire from older systems before checking for a proper spark using a spark tester. In order to determine if you have no spark or only a weak spark, you should use an adjustable spark tester rather than one that is fixed in place. A weak spark will lead to a different diagnosis than one with no spark.
The most effective diagnostic procedures are those in which potential causes may be ruled out as fast as feasible. A weak spark on an ignition system should rule out the majority of primary input sensors. It goes without saying that a weak spark is not brought on by cam and crank type inputs, but a lot depends on the vehicle you’re working on. On the other hand, these inputs cannot result in a spark. It is clear how this distinction will influence how your diagnostic process is conducted.
In particular on Chrysler products, the link between crank and cam timing events might result in no spark. If the cam and crank are out of sync on these cars, the PCM won’t activate the ignition coil. When checked using a digital storage oscilloscope (DSO) or graphing multimeter, cam and crank inputs could seem normal (GMM). The coil output and principal wiring circuits will also seem normal while using a scanner’s bi-directional controls, which can make you think that changing the PCM is the solution. You might discover a slipped timing belt, the main reason for a no-spark, no-start scenario, by checking the cam and crank relationship.
Timing
The most commonly disregarded and incorrectly identified cause of a no-start is improper timing. Perhaps when you think of ignition timing, you picture the crankshaft’s position at the moment the No. 1 plug ignites. Although significant, this is not the only temporal factor that might affect a no-start. The ignition must fire, the injectors must open, and all three events must occur at precisely the right time.
It can be challenging to evaluate the ignition timing on a no-start, but it is still possible by connecting a timing lamp and observing the timing marks when a helper cranks the engine. This may or may not be base timing according to the manufacturer’s specifications, but it does show you where the spark is coming from. This knowledge can help your diagnosis go in the right path with a little common sense.
Additionally, the timing of the valve can be crucial. When the cam timing is off from the recommended range, Hondas are known for running rich. If the start is tried in chilly conditions, this can result in a no-start problem. After cleaning the plugs, the outcome will be a flooded engine that you may start, which could lead you to overlook the real source of the issue.
Fuel
The fuel delivery system and the injector electrical circuit can be divided into two sections for the purposes of fuel system diagnosis. The fuel system has command and fuel supply, similar to how the ignition system includes primary and secondary components.
With a scan tool and a DSO, command, or the injector electrical circuit, is typically diagnosed. It is not a good test to use a noid light that is wired into the wiring harness in place of one of the injectors. Despite being practical, this instrument does not test ground or voltage and does not apply the necessary load to the circuit. The location of the issue inside the circuit can be determined by a DSO, who checks the circuit while it is under load. Voltage and current are measured through DSO testing. Voltage will inform you of both the status of the command and the integrity of the supply circuit. You can determine how well the circuit is working by taking current readings.
By monitoring gasoline flow and pressure, you may check the parts of the fuel delivery system. Test the circuit while it is loaded for the most accurate flow measurement. Testing return-type systems is simple with a flow gauge like the one in the picture on page 32. Returnless systems and variable-speed gasoline pumps both have their own set of issues. Each sort of system should be diagnosed based on its unique traits.
For instance, the gasoline pump system in early Subaru vehicles had two speeds: a slower speed while idle and a quicker speed above idle. As the system switches between them, two separate flows may be visible. If you don’t understand how later models work, like Ford’s returnless/variable-speed fuel systems, they can be quite challenging to diagnose. Utilize a scan tool to find the parameter identifier (PID) that shows fuel pressure to expedite diagnosis. Only if it is accurate is this PID useful. The system’s manual fuel pressure gauge can be used to check the pressure transducer’s functionality.
The theft-deterrent mechanism may be the root of an issue with gasoline supply that is frequently disregarded. The data stream from some manufacturers contains a PID that indicates whether or not fuel is enabled. Later, more on that.
Compression
Check current vehicles for anything that could result in flooding by allowing too much fuel to enter the cylinders. A frequent reason is improper cam timing, particularly in systems with high speed densities. Products made by Honda, Mazda, and Chrysler come to mind when flooding due to timing belt issues.
It’s also possible that the PCM’s cold cranking parameters weren’t properly calibrated. Some of these cars will start once the excess fuel has been removed from the cylinders, but if the source of the surplus fuel is not found, they will eventually stop working again. The next chilly morning will bring flooding because of the slower crank speeds and wider injector pulse width required for cold starts.
Some Nissans will overfuel when cold cranking at higher altitudes. TSB 96-061 recommends replacing the engine coolant temperature (ECT) sensor for 19931995 Altimas. Through deceiving the PCM into believing the engine is warmer than it actually is, the new ECT alters the cold-start injector pulse width. TSB 97-023 for the 19911994 Sentras outlines how to install an altitude switch and subharness to fix the same high-altitude/cold weather starting issues. Vehicles starting at lower elevations than 5000 feet are unaffected by this adjustment. To find any relevant TSBs for the car you’re servicing, consult your sources for vehicle repair information.
The injector circuit might not be the reason for the overfueling on later models that display the same symptom or on vehicles that are not covered by a TSB. Another reason for it can be a shortage of air. On Nissans and many other models, overfueling can be brought on by poor airflow around the throttle plates (and via the IAC, if there is one). The throttle plates can be cleaned, and the minimum air rate can be changed, to remedy this situation. Check that the fundamentals, including the timing, engine oil, and spark plug condition, are all within specs on late-model Nissans.
Theft-Deterrent Systems
Systems that inhibit theft go under many different names. Despite being around for a while, they continue to give rise to numerous no-start complaints. This problem could occasionally persist even after you’ve fixed the car. On several manufacturers, replacing a stolen module without the necessary initialization causes a no-start. In some cases, as when a master key is lost, it could be necessary to replace many controllers.
Unneeded anti-theft system activation will result in a no-start, which could waste time and lead to inaccurate diagnostic findings. A start-and-stall complaint is a typical condition. Disarming the theft system should be the initial stage of your diagnosis if you come across this problem in late-model vehicles. Depending on the model year, Jeeps, for example, will start and stall until you lock and unlock the passenger door or the rear hatch.
The state of the security lights is a crucial factor in theft deterrence. The majority of systems have a dash light that will indicate where the issue is. Because every system is unique, refer to the repair manual. A flashing light while turning on one system might be a sign of a security issue, but it might not be the case for the same make and model in a different model year.
The system’s behavior can vary as well. Some prevent the engine from starting, while others turn off the fuel pump and the spark plugs. The theft-deterrent mechanism frequently permits the engine to start before immediately causing it to stall, as I previously mentioned. Product expertise is crucial in these circumstances.
Even though systems have advanced to make no-start diagnosis much more challenging than in previous years, it’s crucial to remember what is required for a spark ignition engine to operate. Spark, fuel, and compression are still necessary, and they must all happen at the right time. By focusing on this fundamental idea, you may maintain your attention on the task at hand and make the right diagnosis in a respectable amount of time.