Test round relays?, 3 out of four bad? Options

[StarBear]

Just curious- is there a way to test those little round relays? Hard to believe so many were bad, including a brand new one.
Info: 1974 1.8L; Left headlight stopped lifting so naturally first replaced the relay. No go. (IMG:style_emoticons/default/confused24.gif)
Cleaned ground and checked wiring and put a drop of oil in each joint. No go. Put in another relay. No go again. (IMG:style_emoticons/default/hissyfit.gif)
So before digging into the motor, checked out Ian’s video, Haynes, Tech Tips 700, and Pelican Parts Tech to figure out how to address the motor. In a usual last ditch effort to an easy approach, used the tried and true swap with known good relay on the right motor and the left worked! Put ANOTHER new relay in the right and BOTH worked! (IMG:style_emoticons/default/aktion035.gif)
Want to investigate by testing the first three, just out of curiosity.

[Spoke]

Relays are easy to test. You need a 12V power source. You can use an old laptop power supply although it is 19V it will still drive the coil of the relay.

Get your 12V source and apply it between 85 and 86, you should hear the relay click.

With your multimeter set to ohms, check the resistance between 30 and 87a. It should be zero ohms or near zero. Remove the power to the coil and measure resistance between 30 and 87. It should be zero ohms or near zero.

[StarBear]

Relays are easy to test. You need a 12V power source. You can use an old laptop power supply although it is 19V it will still drive the coil of the relay.

Get your 12V source and apply it between 85 and 86, you should hear the relay click.

With your multimeter set to ohms, check the resistance between 30 and 87a. It should be zero ohms or near zero. Remove the power to the coil and measure resistance between 30 and 87. It should be zero ohms or near zero.

Thanks! Still learning…. (IMG:style_emoticons/default/biggrin.gif)

[StarBear]

@Spoke Tested; found two more bad ones and four good ones, though resistance results matched at zero ohms by reversing designations 87 and 87a in instructions (87 with power and 87a without). Correct?

[Mikey914]

You should return the bad relays to the vendor you bought them from. Ours carry a 2 year warranty.

[Spoke]

@Spoke Tested; found two more bad ones and four good ones, though resistance results matched at zero ohms by reversing designations 87 and 87a in instructions (87 with power and 87a without). Correct?

Correct 30-87a w/o power; 30-87 w/power. Conversely, both should be open: 30-87a w/power; 30-87 w/o power.

[VaccaRabite]

So if you put a known good relay in the socket does the headlight work normally?

Thanks!
Zach

[StarBear]

So if you put a known good relay in the socket does the headlight work normally?

Thanks!
Zach

Absolutely. A “good” used one and a “good” new one didn’t work so took the good working one from the passenger side light to the non working driver’s light and presto all was working. Another new on back into the passenger light and all is right again. (IMG:style_emoticons/default/piratenanner.gif)