Test the ignition coil
Fluke analog/digital multimeters can test resistances from 0.01Ω (Type 88) to 32MΩ. This makes testing ignition coils very accurate and easy. A general multimeter cannot test resistances below 1Ω.
Measuring the internal resistance of the coil
If you suspect that the ignition coil is abnormal, you should check the resistance of the primary and secondary coils. The test shall be performed and tested for each joint when the car is warm and when the car is cool. The primary resistance of the coil is small and the secondary resistance is large. The manufacturer's specifications should be specifically consulted. The empirical value is 0-several Ω for the primary, and 10KΩ or more for the secondary.
Test the spark plug connection
A spark plug that has been in use for many years should be inspected whenever there are signs of a possible spark plug problem. Not all connections have the spark plug production date. Due to the high heat, the spark plug base and the spark plug will stick. So removing the spark plug can damage the delicate, brittle wires in the insulation. Therefore, it is necessary to rotate it several times before disassembling. If a problem is suspected, the resistance of the wire should be tested while slowly twisting and rotating it. The resistance value is about 30kΩ/meter. The size of the value is related to the type of line. Some will be much smaller. For accurate measurement, it is best to compare it with the wiring of other spark plugs in the engine.
capacitance
Fluke analog/digital multimeters can also test car capacitors, and a change in the analog helium pointer tells the multimeter that the capacitor is being charged. You can see that the resistance varies from 0 to infinity, make sure that the capacitor should be tested from both directions, but also to detect the capacitance in hot and cold conditions.
Testing capacitor leakage
Use the resistance gear of the multimeter to test the leakage current of the capacitor. The resistance should grow to infinity as the capacitor charges. Any other value indicates that the capacitor should be replaced. The test capacitor is tested by disconnecting it from the car circuit.
Hall-Effect Position Sensor
Hall effect sensors have replaced many ignition points on a switchboard and are used to directly detect the position of the crankshaft and cams in non-switchboard ignition systems, which tell the computer when to fire the coil. A Hall Effect sensor produces a voltage proportional to the strength of the magnetic field passing through it. It can come from a permanent magnet or electrical current.
Testing Hall Effect Sensors
First check the voltage from the battery. Because the Hall effect sensor needs power and the solenoid valve does not. When testing the sensor, first connect the +12V of the battery to the power supply terminal, and use a multimeter to measure the voltage of the signal output to the ground terminal. Insert the gap between the sensor and the electromagnet and watch the multimeter's analog pointer change. The value of the change should be between 0-12V.
Electromagnetic position sensor
An electromagnetic type of position sensor consists of a coil wound around a magnet. Clear procedures for Pickup and Reluctor are critical. The index is generally from 0.8mm to 1.8mm.
Pulse testing of electromagnetic distributors
Disconnect the distributor from the ignition module, set the multimeter to DC voltage and connect it to the ignition head. When the engine turns, pulses appear on the analog needle. If there is no pulse, there may be a fault in the adjustment wheel or the electromagnetic connector. Other electromagnetic position sensors can also be tested in the same way.
RPM
The RPM80 accessory allows the Fluke 78/88 to test the engine's rpm with the secondary ignition pulse of the spark plug. Applicable to both non-distributor systems and conventional systems.
Test engine speed
To test the rotational speed, use the RPM80 electromagnetic induction rotational speed measuring accessory. Clamp the spark plug wire with PRM80 on the multimeter (1) or (2) to suit the type of engine. WARNING: Because of the high pressure generated by the ignition system, the engine should be shut off before connecting and disassembling the RPM80.
Leakage location
Leakage, short circuits, and poor grounding are the causes of many failures. And the phenomenon that manifests always seems to be impossible to start. But using a multimeter can quickly find faults without damaging the fuse. Battery failure due to leakage is often thought of as a short circuit although it may not actually be caused by a short circuit. Actually they may be related to hold memory (KAM) circuits. Using the same troubleshooting techniques as looking for leakage currents, you can find short circuits that are smaller than the fuse current. Although they show different phenomena. Unintentional: Every car manufacturer has a different process for finding leakage currents, and using the wrong test method can lead to wrong results. Please refer to the manufacturer's manual to confirm that you are using the correct procedure.
Examples of Ohm's Law
If a voltage of 0.5V is measured on the ground connection in the starting circuit, and the starting current is 100A, the resistance can be obtained by calculation: E=IxR, R=0.5, 100A, 0.005Ω is too large, so please Clean the connector. A voltage drop of 0.5V tells the same thing, that the connector is dirty or corroded.
Poor grounding
The high resistance to ground is probably the most vexing problem of all. They can produce strange phenomena. When the problem is finally found, it seems that there is no way to start with the phenomenon of the problem. These phenomena include dim headlights, when other circuits work, the headlights come on again, when the headlights are on, other instruments will be affected, and the headlights will not light at all.
For today's new car computer systems, the high resistance of ground terminals and sensors can produce various unforeseen phenomena.
Before connecting the joint, apply some insulating lubricant around it. Corrosion can be prevented in this way.
Pay special attention to the ground terminal of the acid battery. Because acid can accelerate corrosion. Corrosion of the connecting wire and corrosion of the grounding terminal produce the same phenomenon. Just checking the insulation joint does not guarantee that the inside of the connection is good. To do this, disconnect the joint and polish the metal surface with an iron brush or sandpaper.
Voltage drop
Even small voltage losses can cause significant poor performance in automotive circuits. Set the Fluke multimeter to millivolt or V DC, connect the positive terminal of the test lead to the device close to the positive terminal of the battery, and connect the negative terminal to the negative terminal of the battery or ground to activate the min/max function. The flow of current can cause a voltage drop in the part of the component to find the problem. Except when the voltage drop of the electronic coil is large when the engine is started, other parts should not exceed the following values: wiring or cable <200 mV; switch <300 mV; grounding <100mV; sensor connection 0-50mV; connector/ground 0V.
Rear window anti-fog deletion
There are horizontal grid lines on the back window glass, which are conductors made of ceramic and silver. The ends of the wire are soldered to two vertical conductors called bus bars (on either side of the glass window). One end is used as the input terminal (connected to the battery). The other end is the ground of the chassis. When the ignition switch and anti-fog switch are turned on at the same time, current flows through the rear window through a relay. The usual current is about 20A. Grid delete does not heat. So once the location of the open circuit is identified, it can be fixed.
Test the rear window anti-fog removal
Start the engine to maintain speed and turn on the rear window anti-fog switch. The black pen is connected to the vertical binding post, and the red pen is connected to the other binding post. Measure DC voltage. It should be 10-14V at this point. Readings that are too low indicate poor grounding. The black pen is grounded and the red pen tests the midpoint of each anti-fog line. If it is about 6V, it means that there is no open circuit. 0V means that there is an open circuit between the battery and the measuring point. 12V indicates that there is an open circuit between the measuring point and the ground.
