3-Wire Ignition Coil Schematic (Complete Guide)
Content
Below I will talk about a three-wire ignition coil with a diagram of its connection and some useful information.
The ignition coil is designed to supply high voltage to the spark plugs. However, the ignition coil contacts must be properly connected to other electrical components.
Typically, a 3-wire ignition coil comes with a 12V, 5V reference voltage and a ground pin. The 12V contact is connected to the ignition switch and the 5V control contact is connected to the ECU. Finally, the ground pin is connected to one of the vehicle's common ground points.
Power, Signal, and Ground Pins for 3-Wire Ignition Coil
Typically, a three-wire ignition coil has three connections. The 3V pin can be recognized as a power connection. The positive terminal of the battery is connected to the ignition switch, and then the ignition switch is connected to the ignition coil.
The 5V reference pin is the trigger connection. This connection comes from the ECU and sends a signal to the ignition coil. This process fires the ignition coil and applies high voltage to the spark plugs.
Finally, the ground pin provides grounding and protects the associated circuits.
How does a three-wire ignition coil work?
The main purpose of any ignition coil is quite simple. It receives 12V and puts out a much higher voltage. This voltage value will be close to 50000V, given that the primary and secondary windings work perfectly. Here is a simple explanation of how the primary and secondary windings work together to create high voltage.
The ignition coil uses the relationship between magnetism and electricity to generate high voltage.
First, an electric current flows through the primary winding, creating a magnetic field around the coil. Then, due to the opening of the contact switch (open switch situation), this magnetic energy is released to the secondary winding. Finally, the secondary winding converts this energy into electricity.
Typically, the secondary winding has about 20000 jumpers. And the primary winding has from 200 to 300 V. This difference allows the secondary winding to create a high voltage.
The coil can produce much higher voltage levels with a powerful magnetic field. So, the strength of the magnetic field matters, and it depends on two factors.
- The number of turns in the coil.
- Applied current
Where is the spark plug wire coil in your car?
The ignition coil is usually located between the battery and the distributor. The distributor is responsible for supplying high voltage from the ignition coil to the spark plugs.
How can I test a 3 wire ignition coil?
There are three circuits in a three-wire ignition coil: a power circuit, a ground circuit, and a signal trigger circuit. You can test all three circuits with a digital multimeter.
For example, the power circuit should show voltage in the range of 10-12V, and the ground circuit should also show 10-12V. You can test both the power circuit and the ground circuit by setting the multimeter to DC voltage.
However, testing the signal trigger circuitry is a little tricky. To do this, you will need a digital multimeter that can measure frequencies. Then set it to measure Hz and read the signal trigger circuit. The multimeter should display readings in the range of 30-60 Hz.
Quick-Tip: If you find signs of ignition coil failure, perform the above tests. A properly functioning spark plug wire coil should pass all three of the above tests.
Difference between 3-wire and 4-wire ignition coils
In addition to the difference between 3 and 4-pin, 3- and 4-wire ignition coils are not much different. However, pin 4 of the 4-wire coil sends a signal to the ECU.
On the other hand, the 3-wire ignition coil does not have this function and only receives a start signal from the ECU.
Take a look at some of our articles below.
- How to connect ignition coil circuit
- How to check the ignition coil with a multimeter
- How to test a spark plug with a multimeter
Video links
