Some loads draw a different current when they first start. A circuit can therefore fail during the initial attempt yet look normal once it is already operating.

How to narrow it down

Capture the start-up event rather than measuring only steady operation. Check supply drop, wiring condition and the load’s current profile against the correct specification. If the output stage is being assessed, include its current-limit and thermal behaviour in the diagnosis.

What to include with the fault report

State whether the symptom depends on temperature or repeated operation, and provide the start-up capture.

A larger fuse or stronger replacement transistor is not a justified repair for an unexplained start-up overload.

Speak to AXION

For ECU testing and component-level repair, 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 Texas Instruments. The referenced design explains the principle; the vehicle-specific procedure determines the repair.