The horn relay works because when i run jumper wires from the positive post and negative post on the battery, the relay opens up. I checked for 12 volts from the orange wires going to the harness and its there. I would also check for 12 volts with my multi-meter (red lead to the orange wires and black lead to the black wire/horn ground) by pushing in the horn button and it shows 12 volts when it is pressed. Release the horn button and it goes back to 0 volts. But for the life of me, it will not open the contacts in the relay.
Before anything else, are you certain that the horns are working (i.e. will they blow if supplied with battery voltage)?
If you haven't already done so, supply terminal 29 (traced in yellow) in the dwg below with 12 VDC using a jumper. The horns should beep. If they don't, the problem isn't with relay - it is with the horns themselves or the interconnected wiring.
If they do beep, next check is the relay coil's voltage supply and continuity to ground.
Pull the relay and use your meter to confirm two things:
1. That there is 12 VDC at terminal 240 (traced in blue) as shown in the dwg below.
2. With horn button depressed, check for continuity between terminal 28 (traced in red) and ground.
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Nevermind the above, I just figured out what this all means. You have already tested for power and ground to the relay coil - and they are good :
I checked for 12 volts from the orange wires going to the harness and its there. I would also check for 12 volts with my multi-meter (red lead to the orange wires and black lead to the black wire/horn ground) by pushing in the horn button and it shows 12 volts when it is pressed.
So, you have confirmed a constant 12 VDC at 240 and a path to ground on 28 - when the horn button is pressed.
Next, see if you can hear the relay pulling in and out. You'll need a helper. With your ear right up close to the relay, have the assistant repeatedly press and release the horn button. Each time the grounding switch is opened and closed by the horn button, you should be able to hear an audible click from within the relay casing.
If you can't hear it (or you don't have a helper), you can bench test the relay.
Pull it out and run jumpers as follows:
1. From the stab that goes into slot 240 to any convenient 12 VDC source.
2. From the stab that goes into slot 28 to nothing (leave the other end disconnected for now)
3. From the stab that goes into slot labeled 29 to your meter's red probe
4. From the meter's black probe to ground.
When you are all set up, touch the disconnected jumper (from stab 28) to a good ground while watching the meter. You should get a reading of 12 VDC.
If you don't, the relay is faulty and the contacts are not closing.
