What are the four wires of the fuel pump relay?
2 Answers
Automotive fuel pump relay wiring configuration: The four wires of a car fuel pump are as follows: 1. Two wires belong to the fuel level sensor (commonly called the float) - one is the power supply wire, and the other connects to the fuel gauge; 2. The remaining two wires are for the fuel pump itself - one is the power supply wire, and the other is the ground wire. The fuel pump operates with high current, hence its wires are thicker, while the sensor wires are thinner. Additional information: Automotive relay function: It serves as an "automatic switch" that uses small current to control high-current operations. In circuits, it performs roles such as automatic regulation, safety protection, circuit conversion, and switching. If a car relay fails, the simplest consequence is that certain functions may become inoperable.
I recently had an issue with the fuel pump relay during a car repair, and those four wires really can't be connected randomly. Generally, two are control wires: one called terminal 85 connects to the ECU's control signal wire, and the other, terminal 86, is the ground wire. When the car starts and the signal comes, the relay engages. The other two wires are for the main circuit: terminal 30 is the input wire directly from the battery positive, and terminal 87 is the output power wire to the fuel pump. If you DIY a relay replacement and mess up the wiring sequence, the fuel pump might not work or the relay could burn out—I once replaced it and the car wouldn't start, only to find out after much hassle that the terminal 86 ground wasn't properly connected. I suggest checking the manual or asking an experienced person for help before repairing. Wiring is all about small details causing big troubles, especially when it involves fuel system safety. Remember, don't mix up the positions of the main power terminals 30 and 87. The control terminals 85 and 86 can be swapped to some extent, but it's not recommended to tamper with them casually.
