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Constant horn on Evo 8

331 Views 4 Replies 3 Participants Last post by  Mxr156
Hi all,

I have a bit of a wiring gremlin and I wonder if anyone has experienced the same kind of thing.
All of a sudden last night, the horn on my Evo 8 started going off constantly. No one was in the car, no one was near the car so I had to pull the fuse or relay to stop it. Today I've been out there with the volt meter, disconnected the horns themselves so I don't get deafened and reconnected both the relay and fuse.

When the ignition is in the off position the horns get a constant 12v so keep going off. When the ignition is switched to position 1 or 2 the voltage flow stops. Now I have tried multiple relays of the same type however none of them seem to have made any difference.

Is anyone aware of any issues that might cause this at all? And more so what might fix it?

The only thing I can think of is that some water may be loitering somewhere it shouldn't be, but that doesn't make a great deal of sense as if that was the case, when the ignition was on the horn should still be active.

Any help is appreciated, Thanks in Advance.

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The wiring diagram does provide some information that you may find useful:

Rectangle Font Slope Parallel Number

Here is what I gather from the diagram:
  • There is no computer in this circuit, it's only switches and relays.
  • When the system is working normally, there is only one way to activate the horn, and that is with the Horn Switch on the steering wheel.
  • The horn switch, when closed, provides a ground for the relay and will sound the horn.

Check on the location C-129 PIN 15 in the passenger footwell, perhaps that is the connector which got wet?
Rectangle Font Parallel Number Pattern

Check for corrosion of PIN 15 on this connector, which is the horn wire. If there was water in the passenger footwell perhaps this wire has been soaking and corroding. If the wire looks fine, then have to check up the wire to the clock spring and finally the horn switch itself. Something is causing the circuit to ground and activate the relay.
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