Oscilloscope Patterns and Waveforms

Normal Wave Forms:

Abnormal Waveform:

1. Run engine at idle speed.
2. Engine coolant temperature should be at: 85 - 95°C (185 - 205°F), with no electrical accessory loads on.
3. Connect the input probe of the oscilloscope, to the pickup point shown in the circuit diagram, and check the wave form.
- If scope pattern is not as depicted in image, continue with the rest of the component tests before replacing the assembly.

NOTE: Pattern should change as engine speed changes.