Toyota 90987-02006 Relay Assembly

In the car, the application of relay includes fuel injection, horn, starter motor and fog lamps since they need relays to switch on the electrical signals to the units. Relays moved with a low current control circuit to switch on and off a higher current power circuit, and when a relay is bad, the relate component will bad. These relays are usually fitted in the engine bay and in many parts of the car. If a faulty relay is considered, it is required to remove it and test which would involve either a procedure together with some specific instructions or one may have to go to a dealer service department or a repair shop; in case of relays which are faulty ,it is expected that relays have to be replaced as a complete set. In general, there are no hookups that can directly be connected to a relay; therefore, to test it is recommended to check the circuit wiring diagram to identify correct connections. In most of the relays, contacts of two terminals are connected to the control circuit-that is they are connected to the coil of the relay while other two terminals are connected to the power circuit. Relays are mostly provided with markings that help in the identification of the control and power circuit terminals. To confirm, join a fused jumper wire from one terminal of a control circuit to the positive battery terminal, and another fused jumper wire between the other terminal of the control circuit and the negative terminal of the battery; there should be a click sound from the relay. If it does not click, then the jumper wires may have to be changed as they may be polarity sensitive. When placing the wires, verify the relay markings so that continuity should be equivalent to the power circuit terminals. If the relay does not meet any of these test results, then it should be change with a new one.

Some of the electrical fittings in the car include; fuel injection system, horn, starter, and fog lamps which uses relays to send eletrical signals to parts; they feature a low current control circuit to run a high current power circuit. A bad relay will result in the improper functioning of the connected device and majority of relays are usually placed in the fuse and relay compartment of a car engine. If a faulty relay is assumed to be causing the problem it can be withdrawn from use and diagnosed maybe by a specific test or by a servicing outlet. Defective relays have to be replaced in toto ; circuit identification is usually to be found on a label on the top of the relay or, in the case of some boxes, on the inside of the lid. There are some which are involved with the interior fuse box and among them is the starter relay among others. After wiring diagrams have been made, testing is done by ensuring wiring diagram has been well connected; if in doubt more information can be sought. Some of the common relay classifications are basic relay types and their function, normally closed and normally open. Usually terminals 1 and 3 are of control circuit and are connected to the relay coil and terminals 2 and 4 of power circuit. Certain relays may be labeled for control side and power side terminals. To check, attach an ohmmeter between the power circuit terminals; should read no current flow when not powered but when powered, a current flow should be read. With the jumper wires, join one of the control circuit terminal to the positive terminal of the battery, and another end to the negative terminal; the relay should emit a sound as though it has been 'clicked'. If polarity is important, you may have to interchange the jumper wires or use those with appropriate polarity. An indication that relay is defective is if it fails this particular test, then a replacement is necessary.

Defective relays must be replaced as a unit.

If the relay fails the test, it should be replaced.

If any of the relay tests fail, it's advisable to replace the relay with a new one to ensure proper functioning of the associated accessory.

After connecting the jumper wires, check for continuity between the power circuit terminals as indicated by the markings on the relay.

The various relays are grouped together in several locations under the dash and in various locations around the chassis for convenience in the event of needed replacement.

If a faulty relay is suspected, it can be removed and tested using a specific procedure or by a dealer service department or repair shop. Defective relays must be replaced as a unit.

If a faulty relay is suspected, it can be removed and tested using a specific procedure or by a dealer service department or repair shop. Defective relays must be replaced as a unit.

It's best to refer to the wiring diagram for the circuit to determine the proper hookups for the relay you're testing.

Some electrical accessories in a vehicle that use relays include the fuel injection system, horns, starter, and fog lamps.