Ignition System Troubleshooting

Faults in the vehicle’s ignition system are unpleasant in that any of them is always accompanied by serious interruptions in the engine’s operation or a complete stop. The main sign of a malfunction in the ignition system is the complete absence or “weak” spark between the electrodes of the spark plugs. What to do if there is no spark, and where to look for it? Read about it and not only in our material.

Most often, the spark disappears at the very moment when you need to go somewhere. In order not to push the car to the nearest car service, it is important to understand what the operation of the ignition system depends on, then the search for the missing spark will not cause any special difficulties.

At the end of this article, see the video instruction for finding a spark in the ignition system of VAZ cars.

And below we propose to get acquainted with the algorithm for searching for a missing spark in the car ignition system.

Why is there no spark on spark plugs?

There can be several reasons for the lack of spark on spark plugs. Most often, the culprits of the malfunction are:

  1. Accumulator battery;
  2. High voltage wires;
  3. Ignition coil;
  4. Distributor;
  5. Malfunctions in the low voltage circuit.

Ignition System Troubleshooting

Also, in the absence of a spark, special attention should be paid to checking the quality of contacts and electrical connections of the ignition system elements. You can check the status of the contacts simply by tapping them with your hand.

Carefully inspect the wires and blocks of the ignition system. if any dirt, oil or water is found on them, they must be wiped with a dry cloth. After that, try to start the engine, it is possible that this time it will start.

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Battery Check

A clear sign of problems with the battery is a dull and quiet “horn” signal. Also, if there are problems with the battery during the rotation of the starter, as a rule, the indicator lights on the instrument panel go out. In this case, the cause of the absence of sparks may be poor contact on the terminals or low battery.

  • If the terminals are oxidized, they must be cleaned and tightened. In addition, you can use graphite grease, which reliably protects the contacts from oxidation in the future.
  • If the battery is discharged, it must be charged using the charger.

For information on how to properly charge and maintain a car battery, see our battery charging instructions.

High voltage wire test

Next, you should inspect the high-voltage wires: they should have a neat, not “broken-up” appearance, without breaking insulation, otherwise, they will have to be replaced. If the wires are OK, then you can start the search for the spark.

Video: Ignition System Troubleshooting


We recommend starting the search for sparks with spark plug wires. To do this, remove the tip of the spark plug wire from the spark plug and bring it to "mass" (the nearest metal unpainted part of the body or engine) to a distance of 5-8 mm, after which it is necessary to turn on the starter for a few seconds.

The starter rotation must be accompanied by an uninterrupted bright spark of white color with a light blue tint. If there is no spark, the ignition coil must be checked. A spark of purple, red or yellow indicates a malfunction in the ignition system.

It is also worth noting that spark plugs themselves extremely rarely fail all at the same time. In the presence of "sparks" in the spark plug wires, you can check any spark plug by turning it out of the cylinder head and putting the spark plug on it. Touch the metal part of the candle "mass" the car, and rotating the starter, make sure the presence or absence of sparks on the spark plug electrodes.

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It is necessary to change the spark plugs within the time limits established by the maintenance schedule for your car (usually every 15-25 thousand km).

You can learn more about the marking and the number of glow plugs from our material at this link.

Ignition Coil Test

To check the ignition coil, it is necessary to pull out the central wire from the coil from the distributor-breaker cover.

Rotating the starter, make sure there is a spark from the wire, similar to spark plug wires.

  • The appearance of a spark indicates the serviceability of the ignition coil. In this case, the malfunction should be sought in the distribution switch.
  • If there is no spark from the wire, then the cause of the malfunction is hidden either in the ignition coil or in the low voltage circuit.

If there is a malfunction in the ignition coil, it should be replaced with a new one.

Checking the ignition distributor

If you suspect a malfunction of the interrupter-distributor, you must carefully inspect its cover from the inside.

  • If the lid is ok, just rinse it with gasoline,
  • If found to crack, the cover will need to be replaced.

The central carbon contact of the chopper is checked for “freezing” by moving it easily with your finger.

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The rotor isolation of the breaker-distributor is checked for breakdown as follows:

  1. Position the central high-voltage wire with a gap of 5-8 mm from the rotor electrode,
  2. After that, close-open the breaker contacts by hand (the ignition must be turned on).

The appearance of sparks in the gap indicates a malfunction of the rotor, which will need to be replaced.

Low Voltage Test

To check the low voltage circuit, you can use a 12 V test lamp with a power of up to 3 watts. The lamp is connected on the one hand to the low voltage terminal of the chopper, and on the other. to the mass of the car.

After that, you need to manually close the contacts of the breaker-distributor and turn on the ignition. With a working low-voltage circuit, the control lamp should glow when the contacts open, and when they close, go out.

If the lamp does not light up when the contacts are opened, then the malfunction is hidden either in the low voltage wires or in the primary winding of the ignition coil.

The constant glow of the lamp, at any position of the contacts, indicates one of three causes of the malfunction:

  1. Strong oxidation of the breaker contacts;
  2. Open wiring leading from the breaker terminal to the lever;
  3. Broken wiring connecting the movable disk of the chopper with the housing.

If the cause of the malfunction is in the oxidized contacts, then they must be cleaned, after which the clearance should be adjusted.