I want to bench test a 4 spade ( original style ) headlight relay. What can I do? Have a 12v source,ohmeter,and aligator clips.
I'd like to test and listen for that "click"

Click to view attachment

Terminal 56 is 12v
Terminal “S” is ground and normally runs through the column switch as your control signal.

That will make it click


With no power connected to the relay - you should have continuity from terminal 56 to 56a. There should be no continuity between terminal 56 and terminal “F”.

If you want to test it as in car.

12v to terminal 56 but don’t connect the “S” terminal to ground . . . Yet

Should have 12v on terminal 56a. 0v on terminal “F”

Now connect terminal “S” to ground - relay clicks

Should have 12v on terminal “F”, 0v on terminal 56a


[EDIT] forgot to mention this is a latching relay so each click of the solenoid will reverse the state of pins F and 56a. So, if you start this test and get opposite 0v and 12v readings from what I have written, click the relay and the state should reverse.

This might help:

http://www.914world.com/bbs2/index.php?sho...77&hl=Latch

I forgot you wrote that up. Nice job! Bookmarked.

Ran your tests on another relay that has 5 spades.
The instructions show a pin “30” that connects to 56
How does 30 and 56 work ?; and what if 30 is left unconnected in the car ?

On 5 pin relay that superseded the OEM 4 pin relay, Pin 30 cannot be left disconnected.

Pin 30 is the solenoid - needs to be connected to 12v which is coming in on pin 56.

Click to view attachment

K