Lexus 28300-10020 Relay Assy, Starter

Various electrical accessories within the vehicle, such as the fuel injection system, horns, starter, air conditioning/heating system, and fog lights, utilize relays to transmit electrical signals to the respective components. Relays function by utilizing a low-current control circuit to open and close a high-current power circuit. A defective relay can result in improper component operation. These relays are typically situated in engine compartment fuse/relay boxes. In case of suspected relay malfunction, they can be removed and tested. Faulty relays need to be replaced as a complete unit. To test relays, usually marked for identification, it's important to recognize the control circuit terminals (connected to the relay coil) and the power circuit terminals (connected when the control circuit coil is energized). Fused jumper wires are used to connect the control circuit terminals to the positive battery terminal and the ground. A functional relay should click with these connections. Continuity checks are then performed between the power circuit terminals, following the relay markings. If any of the tests fail, the relay should be replaced.