How can I use a multi-meter to test my horn?

Tank97

Tank97

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Apr 11, 2018
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Branson MO
I am trying to figure out if my horn is bad or if my wiring is bad. I've been chasing a horn problem for a while and eventually found out my clockspring was bad. I replaced it today and still have no horn sound. but my horn relay is clicking whenever I hit the horn button. So know I know the problem is between my relay and horn. I bought a multi meter and have been playing with it but still don't know how to test my horn and my horn plug.

Thanks for the help in advanced!
 
Your horn is like any other electrical part, power and ground are needed. If you can hear the relay clicking I would suggest checking to see if you have power at the horn itself as the next step, using your multi meter or just a simple test light. If you do have power then make sure you have a good ground. If both power and ground check out good you have your answer..... bad horn.
 
From the FSM.

DIAGNOSIS AND TESTING - HORN
For complete circuit diagrams, refer to the appro- priate wiring information.
(1) Disconnect the wire harness connectors from the horn connector receptacles. Measure the resis- tance between the ground circuit cavity of the horns wire harness connectors and a good ground. There should be continuity. If OK, go to Step 2. If not OK, repair the open ground circuit to ground as required.
(2) Check for battery voltage at the horn relay out- put circuit cavity of the horns wire harness connec- tors. There should be zero volts. If OK, go to Step 3. If not OK, repair the shorted horn relay output cir- cuit or replace the faulty horn relay as required.
(3) Depress the horn switch. There should now be battery voltage at the horn relay output circuit cavity of the horns wire harness connectors. If OK, replace the faulty horns. If not OK, repair the open horn relay output circuit to the horn relay as required.
 
I don't know where you are with respect to using a voltmeter but I'll just lay it out the way I'd do it. Set the meter to a range that can read voltage on the battery, like DCV or 15V or something like that. Test that you have it setup right by reading the battery voltage direct from the terminals. It should read around 12. Unplug the horn and put the probes into the connector, one in each side. Set the meter somewhere you can see it from the drivers seat. Press the horn button and watch. If the meter reads battery voltage the problem is likely your horn, if the meter doesn't you probably have a wiring issue. Sorry if this is too basic. Wiring can be tough and sometimes people assume allot.
 
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Tank97 said:
I am trying to figure out if my horn is bad or if my wiring is bad. I've been chasing a horn problem for a while and eventually found out my clockspring was bad. I replaced it today and still have no horn sound. but my horn relay is clicking whenever I hit the horn button. So know I know the problem is between my relay and horn. I bought a multi meter and have been playing with it but still don't know how to test my horn and my horn plug.

Thanks for the help in advanced!
Click to expand...
There's a pretty good article on using a multimeter here:
https://sciencing.com/test-multimeters-7464091.html
As it mentions, a 9 volt battery is a good way to get acquainted to the tool without putting yourself at any sort of safety risk or ruining your multimeter.

Also, @Jerry Bransford made a pretty useful post for someone in a similar situation a while back that may be worth referencing: https://wranglertjforum.com/threads/horn-not-working.8502/post-125710
 
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Imapepper said:
Unplug horn, apply +12v direct to horn, any noise?Sometimes a firm smack will loosen a frozen diaphragm too.
Click to expand...
Now that makes diagnosis just way too simple, at least the isolation part of it... :ROFLMAO: :ROFLMAO: :ROFLMAO: What's the adage.... Keep it Simple Stupid!!!
 
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Thank you everyone for the input! found out the horn was bad, so I bought a new one, had to splice a wire and re ground it, but as soon as I plugged it in it went off continuously without anyone hitting the steering wheel button. I pulled the relay and it shut off. So I unplugged the horn and pulled the relay in and out and could hear that it clicked every time I put it back in, meaning I have continuous power to the horn. Did I mess my clockspring up while installing or is there an easy fix that I'm just not thinking of.
 
When you say that you had to splice a wire and re-ground it, what exactly do you mean? Like @K0LCB said, your horn switch is what supplies the ground for the relay. The pic below is out of your FSM and is the entirety of the horn circuit. When the horn button is in it's neutral position (not pressed) terminal B15 of the horn relay is isolated from ground. When the horn button is depressed the relay is activated and the power side of the horn circuit gets power. Did you accidentally splice the red/yellow wire from terminal B15 to ground?

Capture.JPG
 
IMG_0924[1].JPG

At the bottom of the image you can see my old plug. I cut the red and yellow wire and attached it to the new horn. the horn came with a new ground wire so I just mounted that on the horn bracket to create a ground for the horn.
 
Ok, so that's at the horn itself. If you're hearing the relay click as soon as you put install it into the PDC that means that there is a short to ground between terminal B15 of the horn relay and your horn switch. Relays have two sides: a control side and a power side. When you hear a click that means that the control side of the relay is energized and it is "switching on" the power side. In this case, the horn switch energizes the control side of the relay, thus sending power to the horns which sit on the power side of the relay.

Based on your description I would be looking for a short to ground between the relay and the horn switch on the steering wheel.

What I would do is set your meter to check for resistance (or ohms), place one lead on the negative terminal and the other lead on terminal B15 of the horn relay receptacle. If the horn button is not pressed you should be reading an open circuit, which is displayed as OL (out of limits) on your meter. If you do get a measurement that means that the either the horn switch is shorted to ground or the wire between B15 and horn switch is shorted to ground.
 
i probably would suspect clock spring. but that's because i don't know if you know how to replace one. not to say that you aren't capable, but it's been known to happen to folks. could ohm harness side of horn from the relay to the clockspring connector. if that checks, that leaves clockspring and horn button(s). hope this helps
 
It could be the contact pad on the center of the steering wheel take that off and use the continuity function of your volt meter on the pad
 
Okay. so I took the airbag/horn portion of my steering wheel off to see if I could figure anything out. It is very likely that I screwed up the clockspring because I am in no way a mechanic and have never done a clockspring before. There are four bolts on that portion of the steering wheel that I imagine are to provide a ground for the horn. if I touch one of those bolts to the metal part of my steering wheel the horn sounds, which makes me think I messed something up while installing the clockspring. Im gonna do what T Crawford said and check the actual button.
 
There is a small amount of moisture in the middle of my horn button, could that cause the constant blowing of my horn?
IMG_0946.JPG
 
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