I got my hands on a small square automotive relay. The part number is 5L3T-AA. It is about 1/2" square with 4 pin's, all facing the same direction. Does anyone know what pin is for what? I am using it for a set of fog lights.

 

I looked and it's apparently a factory Ford style relay, and I don't have the pinout for it. If you have a ohmmeter, you could test the pins and figure it out. Write back in if you need advice on how to use the ohmmeter.

 

Thanks Franklin2. I do need help, I know how to use an ohm meter but do not know how to test the relay.
[IMG]C:\Documents and Settings\Head Cheese\My Documents\My Pictures\relay.jpg[/IMG]

I labeled the 4 posts (terminals) how do I test with my ohm meter.

Thanks

 

Put your ohmmeter on the rx1 scale, and touch the leads together to make sure it's reading zero ohms. Then put one lead on one post of the relay, and touch each of the other posts with the other meter lead. You are looking for a reading that is not zero, and is not open either. Systematically test between the posts till you get this intermediate reading on your meter. I am guessing it may be anywhere between 10 and 30 ohms. This will be the coil of the relay. Once you find these two terminals, get a small battery charger and put 12v on these two terminals you found, and the relay should "click".

Once you get that right, then put the ohmmeter on the other two posts of the relay. I am going to guess you will get a open reading , and then when you put 12v on the other two terminals, the reading will go to zero. These will be the relay contacts, and is where you will put your load you want to control.

 

Dredging up an old thread, but is first in google results.

The Posts are Labeled from under side, and from top a corner is 'dotted' to show pin 1

Top Down:
*
1 3
5 2

Bottom Up:

5 2
1 3

Weird numbering and layout, but then other relays have 86 87 87a 88mph so.. what ever.

Pins 1 and 2 are the Coil and pins 3 and 5 are the contacts. Not sure of polarity or which pin the battery goes.

Hope this helps any other wayward search engine user

 

Polarity usually doesn't matter on these style relays. It will matter if there is a suppression diode built into the relay or mounted on the terminals outside the relay. But it should be clearly marked if it's like this.