ST1300 horn not working???

Kim.ST.MN

Joined
Jul 20, 2013
Messages
13
Location
Minnesota
Bike
ST1300
1) Pressing horn button the relay switch 'clicks'... but does not turn on the horn.
2) The horn works.... when testing directly to 12v battery.
I do most of my own motorcycle maintenance... but when it come to electrical I seldom have success.
Any guidance is greatly appreciated.
Thanks...
 
The relay may or may not be sending the electrons to the horn., I hear it's possible for the contacts in the relay to get gunked up. That would be there first place I'd check, as well as the wiring. I've had an aftermarket relay go bad on me.
 
docw1 said:
The relay may or may not be sending the electrons to the horn., I hear it's possible for the contacts in the relay to get gunked up. That would be there first place I'd check, as well as the wiring. I've had an aftermarket relay go bad on me.
Click to expand...
I'm inclined then to replace relay to see if that helps. Any chance you could guide me to a source to purchase a relay? I'm looking at Partzilla schematics and have no clue.
 
I'm hardly the go-to guy on mechanics. To me, almost any relay would do. Take a look at the one that's in there now, and try to match it as close as possible. I took my horn out and replaced it with an aftermarket, louder horn which came with it's own relay. Which I would suggest you do also. If you're looking for OEM, go to Partzilla or other parts places that have the schematics to show you what to get.
 
The relay is;
RELAY, POWER (MICRO ISO 4P), P/N 38501-MCS-G01

All of the relays are the same. Swap the horn relay with another one and see if the horn works or not to determine if the problem is the relay.

Quick checks:
- Check your fuses.
- Check the connectors at the horn to see if they are clean, free of corrosion and solid.
- Disconnect the horn wires and apply 12V+ and ground directly to the horn terminals to see whether or not it works.
If it doesn't, the horn needs replacing.
If it does, the problem is before the horn, see below.

Test for circuit continuity:
- Test to see if you have power and ground at the horn connectors. You can do this with a multi-meter, but preferably with a 12V test light. Disconnect the wires from the horn and connect each end of the test light to one of the two horn wires. It doesn't matter which way the test light is connected. When you push the horn button with the key on, the test light should illuminate.
If it does, both the power and the ground circuits are working, so the problem is most likely that the horn needs to be replaced.
If the test light does not illuminate, see below.

Test power circuit:
- Connect the clamp end of the test light to the negative battery terminal. When pressing the horn button with the key on, probe both horn wires, one at a time, with the test light.
If the test light does not illuminate when probing either wire, there is a problem in the wiring, relay or switch that needs to be traced.
If the test light does illuminate on one of the wires, this is the 12V+ power supply wire. Make a note of which wire this is. It should be light green I believe.
Everything in the power circuit from the battery to the horn is good, see below.

Test ground circuit
- Connect the clamp end of the test light to the positive battery terminal. Probe the second wire at the horn. This is the ground wire, not the one that was determined to be the power wire in the previous step above. I believe that the ground wire is dark green.
If the test light illuminates, the ground circuit is good.
If the test light did not illuminate, you have an open circuit in the horn ground wire.

To test for a ground problem, connect the 12V+ power wire to the horn.
Connect a jumper wire from the other horn terminal to a known good ground, preferably the battery negative terminal.
If the horn works when the horn button is pushed with the key on and while the ground jumper wire is installed, there is an open circuit in the horn ground wire that needs to be repaired.
 
Last edited:
SUSPENSION, POWER RELAY
38506-MCS-G00
Retail Price: $5.27
Your Price: $3.93

RELAY, POWER (MICRO ISO 4P)
38501-MCS-G01
Retail Price: $9.80
Your Price: $7.28

These are the two common relays on the parts diagram (7 each)
Not sure which one you want.
But as stated already, you can pull one out and move it around to see if it corrects your issues.
Have you checked to see if one of the wire spades has become disconnected on the horn itself?

Honda 38501-MCS-G01 - RELAY, POWER (MICRO ISO 4P) : Ron Ayers

www.ronayers.com www.ronayers.com
 
Thanks Andrew, you are correct, small phone, big thumbs, poor eyes, and been inhaling brake fluid all day :rofl1:
 
Willsmotorcycle said:
Do you know if it is a factory horn or aftermarket?
Click to expand...
Before you begin playing new parts roulette, you really should determine if the horn is OEM.
The Honda ST1300 does not use a relay for the OEM horn circuit.

However as some aftermarket horns draw a much greater current (often as much as 20 amperes) than the OEM horn circuit was design to handle, adding a relay is a wise move. Typical installation of an aftermarket horn (with relay) places the relay in near proximity to the location of the OEM horn, which allows the use of the OEM horn wires to control the relay. New conductors (larger gauge) to safely carry the greater current would then need to be installed to carry the increased current demands of the aftermarket horn.

If your motorbike does not have an aftermarket horn installed, and you are confident that the relay "clicking" is in direct response to your horn button presses. Then I think you have an electrical mystery, and will need to investigate further.

One place to start would be to identify the relay that is responding to the horn button presses, knowing which relay will be helpful in tracking down the issue.

If you've not yet availed yourself of the wiring diagram for the ST1300, here's the link: Honda ST1300 Wiring Schematic

Just download the PDF and use your favorite PDF viewer.
 
To echo what @Anna'sDad said, when I replaced my OEM horn with Highway blasters, I removed the old horn and mounted a relay exactly where the horn had been - on that strut hanging down inside the fairing. I then installed the new horns behind the mirrors up in the nose of the bike with power from a new circuit and switched using the OEM horn button to trigger the relay.

@Andrew Shadow's troubleshooting guide is excellent.
 
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