Ignition Coil Testing: How to Check & Diagnose (Articles)

What is a Hall sensor and what is it used for?

Actually, it's just a 'modern interruptor' that works without wear and tear.
He sends the 'ignition' signal to the ignition control unit, which then activates the ignition coil. This creates the spark (via the distributor cap, distributor rotor, and spark plug) that ignites the air-fuel mixture in the cylinder.

Of course, there are sometimes multiple Hall sensors in a vehicle, which operate in a similar way in principle - but now we are only talking about the one located in the distributor.

Here are the 3 connections on the Hall sensor:

'+' = Power from the ignition (terminal 15).
'-' = Mass (Grade 31)
'0' = Signal from the Hall sensor to the ignition control unit.


Symptoms of a faulty Hall sensor.

Most often, a complete system failure is preceded by the following symptoms, which often occur sporadically:
- Brief flash of the oil pressure warning light accompanied by a loss of power.
- Sudden engine cut-out (which can often be restarted without any problems).

At this point, it is almost impossible to find the cause, as the error usually disappears immediately and the engine runs without problems.

It then either says 'change it based on suspicion' or 'wait until you have symptoms.'
It might sound a bit 'unprofessional,' but there's no other way to do it (unless you have the equipment to constantly monitor the signal from the Hall sensor).
I, unfortunately, had to experience the same thing.


Exam:

Strictly speaking, it's not the Hall sensor itself that's being tested right now, but rather the 'surrounding components' - and if everything else is working correctly, then it's likely the Hall sensor that's the problem.
Of course, it would be possible to measure the signal from the hall sensor, but in practice, this usually involves too much effort and is therefore generally not done.

Here is the instruction manual 'For checking the hall sensor'.

When checking the spark, proceed with extreme caution, as a voltage of several thousand volts is present!
Make sure to disconnect and use the '4-wire cable' from the distributor cap.
'In a four-cylinder engine, the middle spark plug wire on the distributor cap is connected directly to the ignition coil.'


Step 1: Is the finger still able to rotate at all?

Just remove the distributor cap and have someone briefly start the engine.

While doing this, observe whether the distributor rotor is still rotating.
-> If not, the timing belt may be broken, or there may be a mechanical defect in the timing mechanism.
-> If yes, proceed to step 2.


Step 2: Check the power supply.

To do this, you need a voltmeter that is set to measure direct current (DC) voltage. (Measurement range: DC20V).

- Disconnect the 3-pin connector for the Hall sensor (located on the side of the distributor).
- Hold the red test lead on the '+' terminal and the black test lead on the '-' terminal.
- With the ignition turned on, the voltage should now be approximately 11.5-12V.
-> If that is not the case, the problem is not with the Hall sensor.
- Now, it's important to check if the voltage is still present when a second person briefly starts the device.
-> If the voltage drops completely only when starting the engine, there is a 99% chance that the problem is with the ignition switch.

When doing this, be sure to carefully check the pins in the connector, including the ones at the back, to make sure no cables are loose.
Is the power supply working correctly? If so, proceed to step 3.


Step 3: Check the ignition control unit and the ignition coil.

Simply connect the '0' terminal to ground for a short time while the ignition is on.

THERE SHOULD ACTUALLY BE A SPARK HERE:

If this is not the case, the problem is usually with the ignition control unit.

'Is the spark now jumping?' In 99.9% of cases, it's due to the Hall sensor.

After replacing the sensor or the entire distributor, the ignition timing should definitely be checked.