64 Riv- need help with horn.

[gunther19820]

Working on a 64. Have the service manual and followed it, but have questions. 
 

Horns don’t work, when hitting the horn button. Manual says to disconnect the tan lead ( mine is black), and put to ground. I did. Relay clicks, but no horns. I chased voltage through the harness, I’m at 13V. This is outside of range according to manual- it says coil could be open. I don’t know what that means 
 

so my questions are :

 

1. is my relay bad?

2. Can I bench test horns straight to battery?

 

voltage at horn ring:

 

 

voltage at horn lead, column disconnected

 

Voltage at relay(green wire) with relay grounded

Edited December 30, 2023 by gunther19820 (see edit history)

[gunther19820]

 

voltage at black wire- relay grounded

 

voltage at black wire, relay not grounded

[gunther19820]

Voltage at green wire, relay not grounded (was just ungrounded. Could have been still discharging)

 

page from manual I’m referring to:

[1965rivgs]

Check voltage at the green wire when grounding the black wire. Better yet, do the voltage check at each horn wire when disconnected from horns when black wire is grounded. You should have battery voltage at the horns.

  You can apply battery voltage to each horn with a jumper wire. As long as the horns are properly grounded they should sound.

Tom Mooney

[gunther19820]

Will do. Thanks Tom.  If I’m over the 11V the manual calls out, is it a problem worth caring about, or should the horns still sound? 

[1965rivgs]

  What is your static battery voltage? It's unusual to see over 13 volts at rest. I'm assuming you are checking voltage with the engine not running?

  You should read a few tenths less than battery voltage at the horn wires when the relay is actuated.

Tom

[RivNut]

Have you put a 12V jumper wire directly from the + battery post to the horn itself?   Are you sure the horns are fully grounded through the radiator core support?  I'd check the horns themselves before chasing relays, etc.

[gunther19820]

1 hour ago, 1965rivgs said:

  What is your static battery voltage? It's unusual to see over 13 volts at rest. I'm assuming you are checking voltage with the engine not running?

  You should read a few tenths less than battery voltage at the horn wires when the relay is actuated.

Tom

I had it on a charge earlier in the day. I’ve been chasing wiring issues through this car circuit by circuit and it’s driving me nuts. 

[gunther19820]

30 minutes ago, RivNut said:

Have you put a 12V jumper wire directly from the + battery post to the horn itself?   Are you sure the horns are fully grounded through the radiator core support?  I'd check the horns themselves before chasing relays, etc.

No I havent yet. I wasn’t sure if that relay stepped voltage down or not, and didn’t want to hurt the horns if they were good. 
 

core support is cleaned well, but I definitely need to revisit the horn brackets, and clean up the terminal for 12v as well

Edited December 31, 2023 by gunther19820 (see edit history)

[RivNut]

1 hour ago, gunther19820 said:

No I havent yet. I wasn’t sure if that relay stepped voltage down or not, and didn’t want to hurt the horns if they were good. 
 

core support is cleaned well, but I definitely need to revisit the horn brackets, and clean up the terminal for 12v as well

I'm not really sure about this but I think the horn relay is used to pull 12 volts to the horn directly from the battery rather than through the much smaller gauge wire that is connected to the horn button.  You won't hurt them by applying a full 12V directly to them. Put a star washer behind the head of the bolt that attaches the horn bracket to the core support. The star will dig into the horn bracket and the threads on the bolt should make clean contact with the core support. Hopefully someone has not gotten carried away and created paint that is too thick to allow current (ground) to pass through the entire circuit.  

[gunther19820]

Thanks Rivnut. I’ll be trying this, then reporting back. 
 

 

[RIVNIK]

Had a similar problem. I assumed the horns were well grounded, went through a lot of rigamarole w no results. as a last resort I took the horns off, brightened the contacts, & everything worked fine. the RivNut was correct.

[Loren@65GS.com]

In your first post, you stated that the horn relay clicked. That would be a sign that the relay is good. The relay doesn't "step down" the voltage. In fact, it should allow full battery or charging voltage, less tenths of a volt, pass through the relay from the attached battery cable on the terminal at the bottom of the relay to the green wire terminal. The black wire terminal as you are referring to, is a ground that activates the relay. That black wire goes up to the horn bar. When the horn bar is pushed, the relay is grounded and activated. 

 As been previously stated in another reply, simply check for power at the wire connection at the horn. I like to use a test light rather than a volt/ohm meter when tracking down a problem. If you have power at the horn connection when you press the horn bar, the circuit is fine. Now you have either bad ground at the horn or somewhere in the sheet metal. Or the horns themselves are bad. And as previously stated, the horns can be tested by adding 12 volts to the terminal and grounding the body of the horn. It should sound. If it doesn't sound, the horn is bad. The horn is simply a vibrating electro-magnet. The internals can corrode, and then it can't vibrate. 

 

 Best of luck with finding your solution,

 Loren@65GS.com

[telriv]

When you connect a 12 Volt lead to the terminal & IF the horn doesn't operate while holding the 12 volt wire, with knowing it has a GOOD ground, tap the horn with a hammer/rubber mallet IF there's corrosion/rust inside it may now operate.

 

Tom T.

[1965rivgs]

3 hours ago, Loren@65GS.com said:

In your first post, you stated that the horn relay clicked. That would be a sign that the relay is good. The relay doesn't "step down" the voltage. In fact, it should allow full battery or charging voltage, less tenths of a volt, pass through the relay from the attached battery cable on the terminal at the bottom of the relay to the green wire terminal. The black wire terminal as you are referring to, is a ground that activates the relay. That black wire goes up to the horn bar. When the horn bar is pushed, the relay is grounded and activated. 

 As been previously stated in another reply, simply check for power at the wire connection at the horn. I like to use a test light rather than a volt/ohm meter when tracking down a problem. If you have power at the horn connection when you press the horn bar, the circuit is fine. Now you have either bad ground at the horn or somewhere in the sheet metal. Or the horns themselves are bad. And as previously stated, the horns can be tested by adding 12 volts to the terminal and grounding the body of the horn. It should sound. If it doesn't sound, the horn is bad. The horn is simply a vibrating electro-magnet. The internals can corrode, and then it can't vibrate. 

 

 Best of luck with finding your solution,

 Loren@65GS.com

Loren,

  I never assume a relay is functional just because it clicks. I always confirm voltage output. A bad relay can click when it brings the contact points together but if the points are oxidized or burned, the relay will not transfer the required voltage/amps. An example most people have experienced is when turning the ignition key, hearing the starter solenoid click, but no starter motor engagement. Of course there can be other causes, like a compromised connection in the circuit or a discharged battery, but very often it is because the contacts and/or the contact plate in the starter solenoid is burned and not transferring power, even though the components are coming into contact with one another.

  Although my first "go to" electrical tool is a Snap On test light (which has a bulb with a very low voltage threshold level and also displays voltage in digital format in the handle), one needs to be careful with an inexpensive test light. If the threshold voltage level of the bulb in the test light is not low enough, as in a cheap test light, the results can mislead by indicating there is no voltage at the test point (bulb doesn`t appear to light) when, in fact, there is voltage present, just lower than the bulb threshold. A typical circuit in an old car which may present this case is a gauge circuit with a knocked down voltage level.

  If I`m troubleshooting a computer sensor circuit which are most often low voltage circuits, I wont even think about touching a test light; I`d immediately go to my Fluke DVOM.

  I see many, many folks go down the proverbial "rabbit holes" when sorting electrical issues because they dont start their troubleshooting at the first logical step. When the first logical step is missed, the rest of the troubleshooting tree becomes a convoluted exercise in frustration. My guess is 5 out of 10 people, or more, including techs, get the first step wrong.

Happy New Year

Tom

[telriv]

I've seen replacement relays click because the wire inside is broken.

I remove the cover & solder the wires back together.

 

Tom T.

[gunther19820]

So, both horns have failed the bench test. Pics below. Voltage measured on the spade connector- NOT touching the powered alligator clip - so I know I was measuring across the horn. 
 

 

additionally, I pulled the horn out of my hotrod, dummied it up under the hood of the Riv. Grounded the lead under the dash to the column- horn worked. 
 

Going to grab new horns and try again. 
 

I need to keep this thread alive for when I reassemble the horn button/wheel/ column. Something is off there and I can’t seem to figure it out