You will often see multiple small relays on the board. These are responsible for switching between different communication pins on the vehicle's OBD-II diagnostic port.
Hardware Engineering Team From: PCB Design Lead Subject: Sign-off on c3e-mb-pcb-v4 c3e-mb-pcb-v4
Front-end modules (FEM) and matching circuits for Low Band (LB), Medium Band (MB), and High Band (HB) frequencies (e.g., QPA8685/6 and QPA8675). You will often see multiple small relays on the board
But V4 . It passes ESD (IEC 61000-4-2 Level 4). It passes radiated emissions. It boots reliably at -30°C and +85°C. Medium Band (MB)
This guide is for informational purposes. Always consult the OEM service manual for your specific device before performing hardware modifications.