Where is the car relay
The position of the relay in the car is the same for most cars, and the relay must be installed in the control cabinet or control box. Just find the corresponding relay position according to the position picture below. The relay is in series in the main circuit. You can also find it along the circuit. The relay generally has several main contacts, plus two coil contacts. It's similar to a contactor, but relays generally see contacts, and you should be able to find them according to this feature.
Car relay wiring method with detailed wiring diagram
Relays have four-pin relays and five-pin relays. Let's talk about four-pin relays first. First find out which 2 of the 4 pins of the automotive relay are coils and which 2 are contacts and connect them according to the diagram. The insulation between the 2 pins is the normally open contacts 3 and 4. The other 2 pins are coils 1 and 2. When the switch is turned off, the electromagnetic coils at the 1 and 2 terminals of the relay will combine the 3 terminals with the 4 terminals.