Fluke 125B Oscilloscope Application in Automotive Electronics Testing

Automobile signals including intake and exhaust camshaft position sensors, ignition coils, OCV solenoid valves, throttle actuator motors, injector control circuits, CAN buses, etc. all require waveform detection. This article mainly introduces how to use the Fluke125B oscilloscope to detect automobile signals, as well as examples.

The specific parameters tested include conventional resistance, voltage, pulse, current, and frequency, which often require not only numbers but also waveforms to describe complex and fast signals.

More than just a multimeter, an oscilloscope can be used to find the root cause of a problem and verify the engineer's own guesses. It is also a means of maintenance testing. Today, Antai Testing will share with you the application case of Fluke 125B oscilloscope in automotive electronic testing:

Fuel Pump

The fuel pump is one of the basic components of the fuel injection system of an electronic fuel injection vehicle. It is located inside the fuel tank and its function is to suck the fuel out of the fuel tank and pressurize it into the fuel supply pipe. It also works with the fuel pressure regulator to establish the fuel pressure.

The fuel pump works when starting and the engine is running. If the engine is stopped and the ignition switch is still on, the control module will shut down the fuel pump power to avoid accidental ignition.

Test points: Test the power cord of the fuel pump to check the working status. The current, voltage drop and action can be tested.

Ignition coils

The ignition coil obtains high voltage through the excitation principle for electric ignition.

First, Pin 1 will get voltage and current from the battery. In the excitation part, the number of turns of the ignition coil is greater than that of the previous coil, thereby amplifying the voltage several times and finally achieving ignition. The ECU will also activate the non-conducting ignition coils through the logic circuit and ignite the strokes in turn.

Test points: primary voltage, secondary voltage, impedance, current

Crankshaft sensor

The crankshaft sensor can be regarded as a simple position sensor. It presents the waveform through the peaks and valleys of the gears. It is a typical analog quantity.

Key points of the test: waveform shape, voltage, and group frame. From the analog quantity, we can find the rhythm of the strokes between the pistons, whether there is a misfire point or a broken tooth.