Toyota 90987-02004 Relay

Used in the vehicle are various electrical accessories which use relays to pass electrical signals to components, and in the event that a relay is faulty, the corresponding component does not work as supposed to. These relays are fitted at a number of points in the car. In case the relay is believed to be at fault, it has to be replaced by a dealer or other qualified shops since individual relays have to be replaced en bloc .

In making the vehicle's electrical connections compact, several automotive electrical accessories like the fuel injection system, horns, starter, and fog lamps use relays to switch between the electrical signals and the respective units. Relays work on the principle that low current control circuit can switch on and off the high current power circuit. A bad relay will disable the operation of a particular component; these relays are located in the engine room and in different parts of the car. Certainly, if a faulty relay is identified, it can be replaced after being removed and tested according to the specified process or directly in the dealer service department or any repair garage, whereby a relay requires replacement in its entirety if it has failed. It is usually suggested to use the wiring diagram of the circuit before trying to test a relay to determine the right hook-ups. The control circuit of most relays is completed by two terminals that are connected to the relay coil; other terminals are also provided for the power circuit and are short-circuited when the control circuit is closed. Control and power circuit terminals are mostly labeled to enhance their identification through relays. To verify, place one end of a fused jumper wire to one of the terminals of the control circuit and connect the other end to the positive terminal of the battery, similarly do the same by connecting the other end of a jumper wire to the other terminal of the control circuit and the ground terminal; the relay should make a clicking sound. If it does not click, it is possible that the jumper wires are in the wrong orientation because some breakout board are polarity sensitive: swapping the jumper wires may help. After connecting the jumper wires, what you will do is probe the terminal that has marks 'P' for power circuit for continuity as indicated in the relay diagram. Any of the above tests, if failed by the relay, should prompt its replacement.

Many electric connections of different car accessories apply relays to convey electrical signals to the components, and if a relay is faulty, the related component will not operate correctly. These relays are grouped in several areas under the dash as well as in other areas of the car's chassis to facilitate their replacement. If relay is believed to be at fault, it can be pulled and checked by a dealer or any qualified shop and any faulty relay must be replaced in its entirety.