Another quick wiring question

Started the engine after rebuild for the first time, kept waiting for the cooling fans to come on, but they didn't.

Before I start troubling shooting, a quick question on the cooling fan relay.

I used 6RA relay and wired the cooling fan wiring based on the wiring diagram. There are only 3 wires going into the relay. Wont list the colour of the wires (don't have them handy)

The question I have, can I use a 6RA relay(I have a new one) or should it be the actual cooling fan relay which it seems is unavailable. The original relay has only 3 terminals.

Can anyone provide a simple drawing to wire the 6RA as a cooling fan relay.

Thanks for everyone's help. Couldn't get to this point without this forum.

Submitted by Bfastr@cox.net on Thu, 06/27/2013 - 18:41

I wish you lived closer too! I love doing this stuff. sadly I cant convince my wife to help out, she doesnt get the concept of a car building "bond" I try to tell her it would be like father-son time, but she says no... she has a grease phobia I think.

on another note, I think I am moving closer your direction, from So Cal to the Nashville area as soon as my sale here and purchase there all close. so maybe I will end up close enough to offer some help in person.

I hope my "fix" worked. basically with a four wire relay you need to get +12 to the coil of the relay. the circuit is made when the otter switch contacts close and the relay coil then gets grounded. Then it activates the relay and it allows C2 and C1 make contact allowing +12v to run to the fan motors.

the cars with A/C use a second relay that works in reverse, sort of, they use the contacts to act like a closed otter switch so the fans run all the time the AC is on. but since they hard ground one side of the relay to the frame, they send +12v down the white/blue wire from the AC control to activate relay two. which shorts the ground on relay 1 which makes the mouse trap fall and well... you know the rest !

Bob F

Bob

Submitted by m.giuliani@sym… on Thu, 06/27/2013 - 10:39

Bob, thanks again for your help, I should just move next door to you. It would be a lot easier and I would get my wiring finished.

On a happy note, my rebuilt engine which sat for a few years actually fired up for the first time a week or so ago. Had to rebuild the SU unfortunately for the second time, the previous owner left fuel in them.

Much appreciated.

Submitted by Bfastr@cox.net on Wed, 06/26/2013 - 22:46

Mark, the simple answer is yes, the relay you have will work. The 6RA relays are a weird lot, the second set of numbers tells more about the relay,for ex: the 33222F has four terminals as you mention, the 33252H has three.
The big differences in a lot of the relays so far as i have found is current rating. And some have a diode for reverse protection, Now i dont know it all about Lucas relays, but the majority are at least 20 amp relays, and both fans together is about 12 amps.

Anyway, basically the W terminals are the control voltage for operation, if there is only one W terminal that means the other coil is either grounded to the case, or tied to one of the C terminals. The C terminals are the contacts. At least in my experience, the C2 is the wiper, or the moving contact if that helps. C1 will be normally open and C3 normally closed, that means C2 is connected to C3 with NO power and to C1 when its powered.

I dont remember you mentioning AC in your car, if thats the case then you only have one relay.
C1 should be the BG wire to the fan motors
C2 should be the +12 volt from the fuse
W1 should be the black/red wire to the otter switch

If you are using a 4 terminal relay try this
C1 and C2 the same
W2 to the black/red
W1 jumpered to C2 for the positive 12v

A simple test is to jumper that black/red to ground and the fans should start spinning.

If you get sparks and smoke.... Run away....

But thats how i would wire it. Maybe someone has another idea.

My car has AC so i have a second fan, in my car relay 1 is the 3 terminal and relay 2 is a four terminal

Bob F