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Relay Help Needed

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Tinkerman

Tinkerman

Darth Vader
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I have a relay in my parts system that I bought as a Horn relay. It is a Lucas part number 33302B. I can't find it my Lucas part book. It is stamped LUCAS. It has four terminals marked W1, W2, C1 and C2.
It looks like the one in the moss catalog cat # 542-170 item #38 page 89. Which looks like it interchanges with what they list for an OD relay.

My question is: Do I have an OD relay or a Horn relay, or one that can be used in either application?

If any one can shed any light on this I would certainly appreciate it.

Cheers, Tinkerman
 
Dick, in the TR6, the OD and horn relays are interchangeable. It also has the same Moss # as you found.
 
The overdive relay on my 1958 TR3A has the same lettering on the terminals. A relay is a relay and could be used for the horns as well. I heard that the recent relays are quite expensive. Mine is the original that came with my car.
 

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If you're concerned about which wires go where, you can use an ohm meter to figure that out. I'd imagine that C1 & C2 go together, and W1 & W2 go together. It's most likely a normally open relay, so if you ohm out across the C's and then the W's you will find one set with infinite resistance...that would be where the actual horn circuit would hook up to, and the other set of terminals should give you a reading of probably between 60-100 ohms...just a guess...that would be the coil activating terminals. Those would go to the horn button circuit.
 
C1 and C2 are the (normally open) contacts. W1 and W2 are the connections for the coil.

I learned the hard way once that not all relays are created equal ... turns out some "horn" relays are only momentary duty and will eventually burn out when used in a continuous application (like headlights). But a Lucas OD relay should work fine for horns.
 
Like the plummer that laid the pipe out and marked it with chalk, instead of using a tape, I just slide the cover off and see where the wires go.
no guessing!
Emmett
 
emmett1010 said:
I just slide the cover off and see where the wires go.
no guessing!
Click to expand...
Good idea, but the Lucas relays have the metal cover crimped into place. While it can be removed, it will never be the same afterwards.
 
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