Humvee electrical systems are designed to operate in harsh conditions, but even they require periodic inspection. Diagnostics covers the entire network: starting system, lighting, radio communication, navigation, ECU, sensors and wiring. It begins with checking the integrity of the networks, voltage at the terminals, functionality of relays and fuses.

Particular attention is paid to cable insulation, since breakdowns are possible during vibrations and contact with moisture. If damage is detected, local repairs or complete replacement of wiring sections are carried out. Batteries, generators, control units are also inspected.

For more modern modifications, diagnostics using OBD-II or MIL codes are possible. After repair, the correct operation of all electronic modules is checked, including synchronization with the power unit.