How does the starter relay work on a Mustang? The starter winding energizes, thereby cranking the engine. The starter relay also gets full power to your Mustang’s ignition system for start-up. The same can be said for high-amp devices like sound systems, electric radiator cooling fans, and high-intensity headlights. What happens when the starter relay is stuck? If the starter stays on after the engine has ignited, the main contacts in the starter relay have most likely welded together in the closed position. When this occurs, the starter relay will be stuck in the on position and damage will occur...

Why does my F150 battery drain after sitting overnight? As a result at random times the 4x4 light would illuminate (but the truck wasn't nor went into 4WD mode...light would just illuminate. Battery would drain after sitting overnight. The leak would run down the a-pillar and into the fuse box area the GEM is mounted behind the fuse box. It's a bitch to change. When does the battery light come on on a Ford F150? Most battery lights will come on when the vehicle starts if the computer has detected that the voltage was too low for a quality start....