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78 620 horn diagram? Horn not working


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#1 Speedymaru

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Posted 11 October 2017 - 07:01 PM

I'm wanting to get my horn working. Im not sure where to start. I did a little research and found that the relays go bad pretty often, but couldn't find anything 620 specific. I need to find out where the horn relay is. I already checked the fuse and it's good. Just not sure what to troubleshoot. Any advice is appreciated

#2 Speedymaru

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Posted 11 October 2017 - 07:09 PM

Forgot to mention that I tested the horns and they both work

#3 datzenmike

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Posted 11 October 2017 - 07:56 PM

On the right inner fender is a black plastic box that cobers all of the relays. Take it off and the horn relay is the one closestto the front of the vehicle.It should have a LightGreen a Green and a Green/White wire to it.

 

Try the horn and see if it is clicking.

 

Light green wire is grounded when the horn button is depressed.

Green/White goes to the fuse box and should have 12 volts on it at all times

Green wire goes to the horns.


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#4 Speedymaru

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Posted 11 October 2017 - 08:40 PM

Okay cool. I took the cover off, and I didn't hear a click when the horn was pushed. Does this mean the relay is bad?

#5 datzenmike

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Posted 12 October 2017 - 05:18 AM

Try unplugging several times to clean the contacts

 

 

Check for power on the Green/White wire.

 

Ground the Light Green and see if this works the relay


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#6 Speedymaru

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Posted 12 October 2017 - 03:36 PM

Will try to clean the contacts soon.

I checked for power and there is constant power.

Do I ground the relay itself or the plug? Could I use a 9v battery and connect the positive to the constant tab, and the negative to the light green tab?

#7 banzai510(hainz)

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Posted 12 October 2017 - 03:56 PM

it might need 12volt but I think 9 might trigger the relay and ohm out the contak side for a short


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#8 datzenmike

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Posted 12 October 2017 - 04:08 PM

Try holding the horn on and give it a wrap with a wooden hammer handle.


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#9 Speedymaru

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Posted 12 October 2017 - 05:05 PM

I tapped it a little bit, and now the horn works. It does not sound good, so I'm going to be installing a new horn.

In order to get the horn to work, you have to push on the inner part of the button, closest to the center of the wheel. Is there any way to adjust this?

#10 datzenmike

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Posted 12 October 2017 - 06:00 PM

The contacts corrode like a dirty old copper penny. The best thing is to repeatedly tap the horn button. If the horn is annoying, disconnect them. By tapping the horn several dozen time you will polishing the contact areas. Allow the horn relay to click also to do the same thing.


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