An AC-coupled oscilloscope view emphasises changing parts of a signal and removes its steady offset. It is useful for some ripple checks but cannot alone establish the actual supply level.

How to narrow it down

Keep a suitable DC measurement alongside the ripple assessment. Label the coupling mode in saved captures so another technician knows what the trace represents. This prevents a waveform centred near zero from being mistaken for an absent supply.

What to include with the fault report

Send the raw capture, coupling setting and the point measured.

A useful ripple trace does not replace an absolute-voltage check. Both measurements need the correct instrument range and connection.

Speak to AXION

For complex vehicle-electronics diagnostics, send your vehicle details and fault report. Workshop assessment is in Didcot, Oxfordshire. Suitable postal or remote work is confirmed before booking.

Technical background from Pico Technology. The referenced design explains the principle; the vehicle-specific procedure determines the repair.