?? How to wire a relay ??

wicked fast · #1 (**permalink**) 07-31-2003, 05:37 PM

Hey,

Need a little help from the electrical gurus.

I am going to use the Lucas #33316
relays for the horn and fan.

Could someone tell me what hooks
up to wires #1, #2, #3, and #4 ?

Power in, switch, and fan/horn(s).

Many thanks,
Bill Cook

computerworks · #2 (**permalink**) 07-31-2003, 07:24 PM

I think the 33316 is a SPST (single-pole, single throw), normally-open relay.

Are the terminals marked? Usually, Lucas relays have the "W" terminals for the coil and "C" terminals for the 'closure'...

To close the relay, you apply +12v at one end (like thru a switch) and ground the other end of the W terminals. Then connect the device to be switched across the C connections.

e.g., for a horn relay, put +12 fused on W1 and connect the horn button between W2 and Ground.
Then, attach +12v (also thru a fuse) to C1 and run C2 to the horn "+" terminal, with the case of the horn grounded by the mounting.

(hope this is clear

)

petek · #3 (**permalink**) 07-31-2003, 07:59 PM

Well, I did a web search for the relay, didn't find any pinouts anywhere.

Got an ohm meter? Use the ohm meter to determine the coil terminals (i.e. look for resistance between two terminals).

Don't have an ohm meter? Ok, use a pair of jumper wires from a 12 volt source (car battery would be fine). Touch the wires to pairs of terminals until you hear a click when the relay pulls in.

Once you've found the coil terminals you're home free!

There are a couple of ways of wiring up the relay, depending primarily if you want to switch hot (+12 volts) or switch ground.

Switching ground: Heavy wire from +12 volts (battery positive) to one coil terminal and one contact terminal. Remaining coil terminal goes to the dash switch with a light gauge wire (the switch then is connected to ground). Remaining contact terminal on the relay goes to the hor or fan with a heavy wire. Other end of the fan or horn goes to ground.

Clear as mud?

DAVID GAGNARD · #4 (**permalink**) 08-01-2003, 05:43 AM

Just the way I did it Petek,works like a charm for my electric fan,used a relay from NAPA,mounted the relay near the starter selonoid and ran the heavy wire to the fan,about a foot away.....

David