How to wire the relay and how to use the remote fuel cut-off function in your car?

1,162 Published by admin 5月 12,2022

When installing a wired GPS tracker, we sometimes find a "remote fuel cut-off" function. However, this is often followed by the text "This function is to be used in conjunction with a relay". So what is a relay? What does it do and how is it wired? This article will give you the answer.

A. The role of automotive relays.

Automotive relays can be divided into functional and control relays in terms of use. For example, there are flashing relays, water wiper relays, and so on. Relays that simply turn the circuit on and off and convert are all control relays.

The remote oil/electricity cut-off relay described in this article is a control relay. It is the equivalent of a switch that draws the armature into the circuit by means of a magnetic field, thus driving the contacts to break the normally closed contacts. In this way, it plays the role of changing the control circuit. It is the key to controlling the circuit on and off.

What do common relays look like and how do they work internally

Vehicle Relays Appearance and Work Internally

How to use the car remote fuel cut-off function and how to wire the relay.

The relay is interconnected with the GPS tracker and is controlled by the GPS tracker. When the vehicle is stolen or in an unexpected situation, an SMS command is sent to the GPS tracker (different brands have different commands). When the GPS tracker receives the command to cut off the fuel and electricity, it will start the connected relay to disconnect the power to the ignition. Without the power supply, the car will turn off.


B. The relay wiring instructions.

General remote fuel cut-off relay has 4 wires (according to the following diagram to explain the wiring, other relay principles are the same. (Only the color has some differences.)

First of all, the red wire connected to the car long power supply positive, black wire override, the blue wire connected to the keyhole of the ACC line is the car key open wired off no power on the line. Secondly, if you want to disconnect the fuel and electricity, you also need to connect the following lines. The yellow wire of the equipment connects to the yellow wire of the relay, the red wire of the relay connects to the long supply positive line on the car, and the two yellow wires connect to the two ends of the fuel pump power supply line after cutting.

Relay Cutting Fuel and Electricity Wiring Instructions

Relay wiring instructions


  • According to the above diagram, first of all, you need to find out the car's fuel pump (or starter motor) power supply line with a stylus: car gears are generally OFF->ACC->ON->ST in order, when the car key will gear to ON gear instantly, the fuel pump power supply line will have about 3 seconds of incoming power, 3 seconds after the power supply is disconnected (after the car ignition this line has always had )

  And the car starter motor power supply line is in the car key When the vehicle is started and the key is returned to ON, there is no power to this cable.

  • Once you have found this wire, use an electrician's tool to cut it from the middle of the wire. Connect the wires to the remote disconnect relay as shown in the diagram above and you are done!
  • Many vehicles have a thicker fuel pump supply wire (starter motor). If the owner cuts it off and connects it again, make sure to connect the two ends of the wire securely (for safety reasons). The other thing is to use the cloud platform for remote disconnection and control of the vehicle.

Warm tips: In order to ensure that the wiring is correct and the equipment is normally online, the software of the car tracker has restrictions to prevent traffic hazards when the vehicle is being driven. When the driving speed exceeds 20km/h, the fuel and electricity cannot be disconnected, and when the speed is less than 20km/h, the disconnection command can be executed again. This is to ensure safety on the road.

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