Automotive terms explained
Your car’s fuel pump is the component that moves gasoline from the tank to the engine at the pressure and volume needed for combustion. In modern fuel-injected vehicles, that means an electric pump submerged inside the fuel tank. Older vehicles and some performance builds use an inline pump mounted on the frame rail. The most…
The Controller Area Network (CAN bus) is the two-wire communication system that lets your car’s electronic modules talk to each other. Instead of dedicated wires between every sensor and computer, all modules share a twisted pair of wires (CAN High and CAN Low). When the CAN bus fails, you see everything from a no-start to…
Your car’s fuse box is the electrical panel that protects every circuit in the vehicle—from headlights and radio to the fuel pump and ECU. When a circuit draws too much current, a fuse blows to stop the wiring from melting or catching fire. Most fuse boxes use blade-style fuses in four common sizes (Mini, Low…
An automotive relay is an electrically operated switch that lets a small electrical signal control a much larger current. It sits between a low-current circuit (like the ignition switch) and a high-current device (like the starter motor, fuel pump, or radiator fan). When the relay fails, the component it powers stops working. You can test…
A multimeter is the quickest way to confirm whether a dead battery, failing alternator, blown fuse, or faulty sensor is behind your car trouble. For most DIY tests, you’ll work in DC voltage (measuring the 12V system) and continuity (checking fuses and wires). A few targeted measurements can save you from throwing parts at a…
A parasitic battery draw is any electrical load that continues draining current after the ignition is off. A normal vehicle draws 20–50 milliamps (mA) to keep the clock, radio presets, and security system alive. Anything above 50 mA is excessive and will drain a healthy battery in one to three days. If you find a…
An AGM (Absorbent Glass Mat) battery is a sealed lead-acid battery that holds its electrolyte in fiberglass mats instead of free-flowing liquid. It’s spill-proof, charges faster, and handles deeper discharges than a traditional flooded battery, but costs more—typically $200–$350 versus $100–$150. If your vehicle has start-stop technology, heavy electronics, or you need a leak-proof design…
The ECU (Engine Control Unit) or ECM (Engine Control Module) is the main computer that manages your engine’s performance. It controls fuel injection, ignition timing, idle speed, and emissions based on sensor inputs. If your car runs rough, stalls, or triggers the check engine light, the ECU is a likely suspect—but many problems turn out…
Every U.S.-market car built since 1996 has a standardized 16-pin OBD2 port under the dashboard. A simple scanner plugged into this port reads diagnostic trouble codes (DTCs) that explain why your check engine light is on. You can handle many basic diagnostics yourself if you know how to pull codes, what they mean, and when…
The starter motor is a high-torque electric motor that cranks your engine until it can run on its own. When you turn the key or push the start button, the starter engages a small gear (the pinion) with the engine’s flywheel ring gear and spins the engine at roughly 150–250 RPM—fast enough for the fuel…