People use a fuel pump relay diagram to locate the control circuit terminals and the power circuit terminals on a fuel pump relay, as eBay explains. This diagram is typically located on the casing of the fuel pump relay.
If a fuel pump relay diagram is not available, the individual needs to look at the relay's mounting base to identify the terminals. The two thinner wires that connect to the relay supply the control circuit terminals, while the two thicker wires supply the power circuit terminal, according to eBay. Once the individual identifies the terminals, he can determine if the fuel pump needs to be replaced by checking the terminals for infinite resistance using an ohmmeter.
A fuel pump relay is an important component of a vehicle because it facilitates the pumping of fuel from the fuel tank to the vehicle's engine, according to eBay. In order to function, a vehicle's fuel pump relies on electricity generated by an oil pressure device inside the engine, as Do It Yourself explains, but the engine must run for a short time in order to generate this oil pressure. The fuel pump relay operates during this time period, providing electricity to the fuel pump when the vehicle first starts running.