1942 Mercury horn relay question.

S

signsup

Senior Member
I've got the correct wiring diagram, but it really doesn't tel me why things are the way they are, so before I start disconnecting wires, wanted to check here. Charging my battery and cleaning up some of the wiring on my recently acquired 42 Town Dedan. Bubba has it converted to 12v with a high torque starter wired to a keyed ignition.
When I disconnect and connect the battery cables the horn relay clicks as if it is being energized. I get no horn to the trumpets and the horn ring on the steering wheel does nothing, so maybe a bad relay. But, if i disconnect the realy from the four wires running to and from it, am I affecting anything else? Does power need to go through this relay to someth other component?


I'm tracking down a slow drain on the battery and it may be related to this relay.
 
signsup said:
I've got the correct wiring diagram, but it really doesn't tel me why things are the way they are, so before I start disconnecting wires, wanted to check here. Charging my battery and cleaning up some of the wiring on my recently acquired 42 Town Dedan. Bubba has it converted to 12v with a high torque starter wired to a keyed ignition.
When I disconnect and connect the battery cables the horn relay clicks as if it is being energized. I get no horn to the trumpets and the horn ring on the steering wheel does nothing, so maybe a bad relay. But, if i disconnect the realy from the four wires running to and from it, am I affecting anything else? Does power need to go through this relay to someth other component?


I'm tracking down a slow drain on the battery and it may be related to this relay.
Click to expand...
Good guess. Likely the relay is the cause of the battery drain.
You could just disconnect the power wire (the only one that is hot).
 
signsup said:
But, if i disconnect the relay from the four wires running to and from it, am I affecting anything else? Does power need to go through this relay to some other component?
Click to expand...

This is how to wire the relay. When the horn button is pushed, it is then grounded. When the relay is grounded and with a fused 12 volt source, the relay is switched on and power is then sent from the battery to the positive horn terminal.

560430
 
So, I'm presuming the realy is bad with the clicking sound when energized. Bubba converted this 42 Mercury to 12v with all kinds of modern wires running all over the place, keyed ignition, 12v gauges and a tach on the radio speaker grill that glows orange upon start up. It's all coming out.
But, presuming again, that possibly the 12v battery going to the 6v relay and horn without a resistor, killed the relay. I'm leaving it 12v, so do I replace the relay with a OE 6v relay and insert a resistor into the circuit? Or is there a 12v relay that will wire up to the horns? I'm replacing the realy anyway, but if I can replace it with one part instead of two, it makes my life easier.


Thanks in advance. Cleaning up and painting the trumpets while I research. Put in new 12v battery today and ithe car purrs like a kitten. I'm fallin in love with it.
 
With your current 4-wire relay what do you measure with a multi-meter at these connections?

#30 - 12 volts, which it should be?
#86 - 12 volts, which it should be?
#85 - no voltage?
#87 - no voltage?

Check continuity:

#87 to the horn terminal? - should show minimal Ω resistance
#85 to ground? - should show minimal Ω resistance

Please check before you throw another relay at it.

If you hear a click when you connect the battery, terminal #85 is grounded.
If it is grounded, you will have voltage at terminal #87

Glenn
 
Here is a pic of my current (no pun intended) relay. Three wires. Perhaps the mounting bracket is a ground. Presume this is OE relay, but that's just from the crusty condition of it, can't find or read any part numbers.
 

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signsup said:
But, if i disconnect the realy from the four wires running to and from it, am I affecting anything else? Does power need to go through this relay to someth other component?.
Click to expand...

Please test your currently installed four wire relay first
 
The original three wire relay has a wire that is hot all the time the ground comes from the horn button and a wire goes to each horn.
 
I've got the relay and trumpets out of the car. Presume I can bench test the realy and horn on a 6v or 12v battery? I have both.
 
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