how to test a relay ?

[Tazkb]

any one know how to test a relay using a meter ? please

 

[Robert Nick]

Reply

At first you need to check the resistance through the Relay Coil. The Relay Coil Terminals should be marked on the Cover. The resistance should be less than 10 ohms. High Resistance (> 1 Meg-Ohm) means the Relay Coil is Open. Most Automotive Relays are either SPST (Single-Pole/Single Throw), SPDT Single-Pole/Double-Throw, and DPDT (Double-Pole/Double Throw). I prefer to apply 12VDC to the Relay Coil and check the Resistance from the Common Pole to the NO (Normally-Open Contact should read 0 Ohm). If you have a SPDT Relay the Resistance of the NC (Normally-Closed Contact) will be High Resistance when the Relay Coil is Energized and the NO Contact will have a low resistance around 0 ohms.

The Relay Cover should also have the Terminals marked by a Diagram for the NO and NC Contacts and Common Pole.

Sorry I don't have a drawing to represent this explanation.

 

[hunter1956]

Since most relays on the car are the same, select one that is the same and you know is good, and substitute it for the one you suspect is bad. If the problem circuit now operates correctly, you know you have a bad relay. (Or do what Robert Nick said)