How can you determine if a relay is bad?

[SAWYER]

I am trying to figure out if a relay is bad, I checked my fuse and it was good. The relay are the large black things correct in the fuse box?

 

[Pacfanweb]

Swap the one you think is bad with another one that's the same amperage. Easiest way.

 

[Elstupido]

If you have a multimeter, you can check resistance on the coil of the relay. You should have a resistance reading on your meter. If no reading, then the relay coil is gone, and bad.

If you do have a reading, my guess is around 1 ohm, then you can still have problems with the contacts of the relay, being carboned up or corroded.

 

[Bignate603]

Originally posted by: Pacfanweb
Swap the one you think is bad with another one that's the same amperage. Easiest way.

Yup, relays aren't too pricey and you may have a few in your car that are rated for the same amperage to swap around.

 

[rudeguy]

Originally posted by: Bignate603

Originally posted by: Pacfanweb
Swap the one you think is bad with another one that's the same amperage. Easiest way.

Yup, relays aren't too pricey and you may have a few in your car that are rated for the same amperage to swap around.

Agreed. You can check it with a test light but swapping it with another is always my first option.

(edit: I did car audio for years and fried my share of relays)

 

[mooseracing]

Check for voltage to the coil side, make sure there is a good ground on the other term, apply voltage or check for votlage at the trigger. If the relay doesn't open or close , which means apply or remove voltage (depending on NC or NO) then replace the relay.