Short in horn circuit?

Friend has a 2010 Murrano. About 6 months ago, had front end of car replaced, such as grill, radiator. Couple months later, horn fuse starts blowing.

Today, we looked at the horns. I am thinking they were miswired, because one horn has black wire attached to ground, and the other horn has green wire attached to ground. I reversed so that both horns have black wires on ground connection. Fuses are no longer blowing and all seems good.

First of all, am I correct that they were miswired, or is it normal to have the two horns wired opposite polarity of each other (one horn had green on top, black on bottom, other horn black on top, green on bottom)?

Also, I had both horns completely disconnected from the circuit, but still mounted in the car, and there is continuity between both connection terminals on both horns, and thus all terminals were also connected to ground. Is that normal?

I've attached pics of the horns BEFORE I rewired it. The left horn was the one I swapped and put the black connector on the bottom, which is connected to the ground.http://https://drive.google.com/file/d/0B2bo3-wJGfvVSEJlVVotcDdBemNuODBBTElKYVI5ZVM3amdV/view?usp=sharinghttp://https://drive.google.com/file/d/0B2bo3-wJGfvVUnZrVUFQRVNwSHdVQU15Z0R3LTlyUVJCMFJj/view?usp=sharing

Your pictures didn't show up. To insert pictures on this forum you need to upload the photos to a sharing site, then link to the photo location in your post.

Without looking at a wiring diagram, you're probably correct that the horn wiring should match between the two horns, and likely the black should be connected to ground for both horns. Keep in mind though also that often the horn fuse is the same as the accessory outlets (aka "cigarette lighter") so a fuse that's blowing could also be due to something plugged in to those.

The horns have a voicecoil, similar to a speaker, and therefore you will have a low resistance reading through a working horn. It will be low resistance, but not a dead short. That is likely why you are questioning if all terminals are effectively shorted to ground. If you set your meter to measure resistance instead of continuity you will likely see a few ohms of resistance through the horns.

-Rod

Your pictures didn't show up. To insert pictures on this forum you need to upload the photos to a sharing site, then link to the photo location in your post.

Without looking at a wiring diagram, you're probably correct that the horn wiring should match between the two horns, and likely the black should be connected to ground for both horns. Keep in mind though also that often the horn fuse is the same as the accessory outlets (aka "cigarette lighter") so a fuse that's blowing could also be due to something plugged in to those.

The horns have a voicecoil, similar to a speaker, and therefore you will have a low resistance reading through a working horn. It will be low resistance, but not a dead short. That is likely why you are questioning if all terminals are effectively shorted to ground. If you set your meter to measure resistance instead of continuity you will likely see a few ohms of resistance through the horns.

-Rod Thanks shorod. That makes sense now. I saw the diagram and there was nothing else in the horn circuit. I tried posting link to my google drive with the pics. Not sure why they didn't show up. Guess it's not necessary now unless you'd like to see the diagram or pics. Thanks

Your pictures didn't show up. To insert pictures on this forum you need to upload the photos to a sharing site, then link to the photo location in your post.

Without looking at a wiring diagram, you're probably correct that the horn wiring should match between the two horns, and likely the black should be connected to ground for both horns. Keep in mind though also that often the horn fuse is the same as the accessory outlets (aka "cigarette lighter") so a fuse that's blowing could also be due to something plugged in to those.

The horns have a voicecoil, similar to a speaker, and therefore you will have a low resistance reading through a working horn. It will be low resistance, but not a dead short. That is likely why you are questioning if all terminals are effectively shorted to ground. If you set your meter to measure resistance instead of continuity you will likely see a few ohms of resistance through the horns.

-Rod

Also, any idea why it took so long for the fuse to start blowing? We estimate that had been miswired for a couple months before it started blowing fuses. The horn fuse was blowing immediately as soon as power was applied (ignition turned on), until miswire was corrected.

Also, any idea why it took so long for the fuse to start blowing? We estimate that had been miswired for a couple months before it started blowing fuses. The horn fuse was blowing immediately as soon as power was applied (ignition turned on), until miswire was corrected.

Nope, that's actually why I was suspecting that the fuse is shared with another circuit. I would expect that the horn circuit is hot at all times rather than only when the key is on. With the miswire I also wouldn't have expected it to blow the fuse until the horn button was pressed, unless there was something else in the circuit that was blowing the fuse.

-Rod

Nope, that's actually why I was suspecting that the fuse is shared with another circuit. I would expect that the horn circuit is hot at all times rather than only when the key is on. With the miswire I also wouldn't have expected it to blow the fuse until the horn button was pressed, unless there was something else in the circuit that was blowing the fuse.

-Rod

Here is the horn diagram/schematic. Maybe this will help.
https://carmanuals2.com/get/nissan-murano-2010-horn-section-hrn-48865

hER

Per the wiring diagram, terminal 1 should be the green wire connector which is the terminal that would have battery power to it when the horn relay is closed. Also per the diagram, the horn button should activate the horn anytime the horn button is pressed, not just when the key is on.

If the Murano has a panic alarm feature, then the IPDM also can control the horn, which might explain why the fuse would blow maybe when the alarm is disarmed. I still don't see why the fuse blowing would seem to be associated with the key being turned on, or why it didn't start causing issues right away with the miswire, unless there is some aftermarket security system installed that is not configured correctly now.

At a minimum though, connecting the green wire to the non-ground terminal on the horn is the way it should be connected per the diagram. Does the horn work properly now?

-Rod

Per the wiring diagram, terminal 1 should be the green wire connector which is the terminal that would have battery power to it when the horn relay is closed. Also per the diagram, the horn button should activate the horn anytime the horn button is pressed, not just when the key is on.

If the Murano has a panic alarm feature, then the IPDM also can control the horn, which might explain why the fuse would blow maybe when the alarm is disarmed. I still don't see why the fuse blowing would seem to be associated with the key being turned on, or why it didn't start causing issues right away with the miswire, unless there is some aftermarket security system installed that is not configured correctly now.

At a minimum though, connecting the green wire to the non-ground terminal on the horn is the way it should be connected per the diagram. Does the horn work properly now?

-Rod

Yes, horn seems to be working properly. The horn does work without the key turned on. I'm not sure if his alarm is aftermarket or not. Yeah it's odd why it wasn't blowing as soon as it was miswired. If he has anymore problems, he will need a mechanic. Thanks for your help.