It's not the best idea to run higher power horns from the stock wiring. You will need to use the stock horn wiring for the trigger on the new horn relay and power the horns directly from the battery. This will both reduce strain on your horn circuit and enable the horns to buzz at full volume. I have read about many issues developing after using the stock wiring to fully power aftermarket horns. It generally doesn't seem like a good idea. An additional relay to the battery is the way to go. Different relays have different pin placements, so the exact wiring will depend on your specific relay you get. Here is a generic diagram that will give you a basic idea of what you will be wiring.

As for removing the front grille, it is most likely necessary although it's not as difficult as it seems. I don't believe it would be very pleasant to install the new horns with the front grille in place.

I believe subispeed sells brackets to install new horns on. I think they even put together some all inclusive kits with brackets, wiring and relays. Most people want them directly behind the grille vents for max forward volume, plus they look neat.

As for installing them on the factory brackets, I don't know that one but I'm sure someone with more knowledge of the subject will hopefully help out.

Good luck.

 

It's not the best idea to run higher power horns from the stock wiring. You will need to use the stock horn wiring for the trigger on the new horn relay and power the horns directly from the battery. This will both reduce strain on your horn circuit and enable the horns to buzz at full volume. I have read about many issues developing after using the stock wiring to fully power aftermarket horns. It generally doesn't seem like a good idea. An additional relay to the battery is the way to go. Different relays have different pin placements, so the exact wiring will depend on your specific relay you get. Here is a generic diagram that will give you a basic idea of what you will be wiring.

View attachment 555691

As for removing the front grille, it is most likely necessary although it's not as difficult as it seems. I don't believe it would be very pleasant to install the new horns with the front grille in place.

I believe subispeed sells brackets to install new horns on. I think they even put together some all inclusive kits with brackets, wiring and relays. Most people want them directly behind the grille vents for max forward volume, plus they look neat.

As for installing them on the factory brackets, I don't know that one but I'm sure someone with more knowledge of the subject will hopefully help out.

Good luck.

Thank you for this informative reply. But additional questions/comments:

The word and function of "relay" is a mystery to me. (Yeah, I know, dude with a PhD. . . .) I don't believe I've ever seen one, or know how to determine appropriate compatibility. "Different pin placements." Huh? And, I assume use of a relay will allow me to keep the stock wiring, yes?

Grill removal is, I think, a non-starter. As noted, I don't have a garage and presently live in a complex, at which there are rules about outdoor auto-repair. Besides, I tried something like this many years ago when I tried to replace the damaged fender on a `74 Plymouth Duster (ohhhh, that slant 6); disaster ensued. So, there's got to be another way.

Finally, how to identify the terminals described in the graphic? Does Subaru have a schematic that would show me?

Apologies for total ignorance in advance 😬. . . .

TRB

 

You need to start teaching yourself the basics. Google, "how does a relay work", for starters. I don't know of a simple plug and play solution.

Here are two horn install threads for the 2019 Forester, which is the same as the 2020 and 2021 models. Both involve removing some bodywork.

This thread, and the references within, covers installation of Hellas on a 2019.

('19+) - 2019 - Hella Horn Mounting Area?

Sooo it looks like the horn set up is totally different from the SJ series. Any advice for the mounting area? How much of the front horn's (the stock on visible in the grill) can be moved so the wiring reaches the middle of the I pillar?

www.subaruforester.org

This thread covers install of JDM (Japanese Domestic Market) horns.

('19+) - Subaru JDM Dual Horns H3717SJ000

I got my shipment from japanparts.com today which included the Subaru JDM Dual Horn H3717SJ000 for my 2020 Touring. The Dual horns are a bit louder than the OEM standard horns... They were pretty much plug and play except for the right hand (low) horn needed to use a different mounting hole...

www.subaruforester.org

 

For the wiring part, if you are going to use Hella horns (or any other that draw more current than the stock horns) the most foolproof method is to buy the wiring harness from Subispeed. I don't think you can mount new horns in front of the radiator/condenser, which is where they should be, without at least removing some front trim panels, and if you tried to get by with removing only the upper trim panel and just reach down I think that would be very difficult. So if you really can't move the bumper where you live, installing new horns yourself may not be feasible.

With regard to mounting the horns, Subispeed claimed to me in an email that their mounting bracket for the Hella horns, which could also be used for the PIAA horns does not fit the SK Forester. I'm not sure they are correct, but that was their response to me when I raised this question.

I have the PIAA Superior Bass horns on order, but plan to remove the whole bumper/grill assembly to mount them. I plan to use the stock wiring (the current draw for the PIAA horns is similar to the stock horns, so no need for relays). I believe that the mounting point for the horn over on the passenger side can be used as is, but for the center horn I anticipate needing to fabricate a short mounting bar out of flat aluminum stock in order for the horn opening to point down. I will make my own ground wires and run them to a suitable grounding point. I don't know if the stock horn wire terminals will fit onto the PIAA horn tabs without modification, but I have a good collection of small low voltage terminals I can use to modify that situation as needed.

 

For the wiring part, if you are going to use Hella horns (or any other that draw more current than the stock horns) the most foolproof method is to buy the wiring harness from Subispeed. I don't think you can mount new horns in front of the radiator/condenser, which is where they should be, without at least removing some front trim panels, and if you tried to get by with removing only the upper trim panel and just reach down I think that would be very difficult. So if you really can't move the bumper where you live, installing new horns yourself may not be feasible.

With regard to mounting the horns, Subispeed claimed to me in an email that their mounting bracket for the Hella horns, which could also be used for the PIAA horns does not fit the SK Forester. I'm not sure they are correct, but that was their response to me when I raised this question.

I have the PIAA Superior Bass horns on order, but plan to remove the whole bumper/grill assembly to mount them. I plan to use the stock wiring (the current draw for the PIAA horns is similar to the stock horns, so no need for relays). I believe that the mounting point for the horn over on the passenger side can be used as is, but for the center horn I anticipate needing to fabricate a short mounting bar out of flat aluminum stock in order for the horn opening to point down. I will make my own ground wires and run them to a suitable grounding point. I don't know if the stock horn wire terminals will fit onto the PIAA horn tabs without modification, but I have a good collection of small low voltage terminals I can use to modify that situation as needed.

Back when I was looking at horn upgrades (2017 Prem Forester) I decided to go with the same Piaa 85115 Superior Bass kit, or actually get a 4horn 80's Buick/Caddilac set. Both have that low retro sound. I believe the Forester is already "relayed" if anyone can confirm.

 

If I were in your shoes, Id get the horns I want, then have a auto stereo shop install them. This would be simplistic for them.

 

You're going to have to pull the front bumper. There just isn't any other realistic way to get to the horns. It isn't difficult, or even all that time consuming. It's a bunch of pop-clips and a little bit of pulling.

I've been running the Hella Sharptones for almost two years now on the stock wiring in my 2017. Only one issue I had turned out to be a bad chassis ground caused by an incompetent body shop performing repairs. I used a Grimmspeed BroTie to mount the horns and extended the wire from the stock second horn location in the side of the bumper to reach the second horn mounted at the front.

I use my horn a lot (there's a new traffic circle in the area and people haven't figured out that you don't have to YIELD TO A COMPLETE STOP when there is NO TRAFFIC in the circle) and it hasn't ever blown the OEM fuse, so i don't think it's going to cause an issue to use the stock wiring.

 

Consider the PIAA 85110 400/500HZ horns.
I installed these on my 2019. I have also installed them on a 2012 Impreza and a 2013 XV.
They are completely plug-and-play. Nor relay or additional wiring necessary. They connect using the factory wiring harnesses (though you will need to wire to a ground, which is very easy to do).
They can be installed without removing the grille and without removing the bumper. It’s snug, but there is room to install the front horn without removing the grille. The lower horn can be accessed through the fog light location or from below if you remove the undercarriage cover. I installed my horn when I did the fog light install.

 

Consider the PIAA 85110 400/500HZ horns.
I installed these on my 2019. I have also installed them on a 2012 Impreza and a 2013 XV.
They are completely plug-and-play. Nor relay or additional wiring necessary. They connect using the factory wiring harnesses (though you will need to wire to a ground, which is very easy to do).
They can be installed without removing the grille and without removing the bumper. It’s snug, but there is room to install the front horn without removing the grille. The lower horn can be accessed through the fog light location or from below if you remove the undercarriage cover. I installed my horn when I did the fog light install.

How did you mount the brackets? Plug and play? No wire cutting or splicing? Just remove the factory horn??

 

Installed the PIAA Superior Bass horns tonight. Can not imagine doing it without removing the bumper. Bumper removal was not difficult, though I ran out of daylight and putting it back on after dark was a bit tricky. Would have been much easier in daylight. I like the sound. Not overly loud, but a much deeper tone than the OEM horns.

The horns were harder to install than I expected. For the front horn, I created a little bracket, so the horn opening could point downwards. The only difficulty here was that the stock I had selected was too wide where it mounts to the body, so I had to cut it down. For the passenger side horn, it worked to just attach it where the OEM horn was attached, but would have been easier if the mounting arm on the PIAA horn were just a little bit longer. It was a tight squeeze for the wires. I considered making an extender, but decided it was not worth the effort, given that it worked and I was losing daylight. If I need to remove the bumper for some other reason later, maybe I will create a short extension.

I used the horn mounting bolts for the grounding location for both horns, as do the oem horns. The OEM trigger wires fit onto the PIAA tabs easily. The PIAA-supplied ground tabs needed to be forced/bent a bit to fit around the OEM attachment bolts, but it worked OK.

Pictures attached. It was dark by the time I was taking the pictures, so they are not great photos, but hopefully will be helpful anyway.

 

All the information I found was old.

Has anyone put a better horn like the Bella Superhorn in a 2019+ Forester?

Anything that would be relatively easy without modifying or splicing wires?

THANKS

 

Here is one recent thread
('19+) - 2021 - Another Horn Question - like to...

 

Here is one recent thread
('19+) - 2021 - Another Horn Question - like to...

I like the sound of the superior bass horns. Do you think the bracket you made is necessary? Cant you just attach the bracket to the one where you removed the OEM horn?

 

It might be in the thread @DaveL mentioned, but I remember coming across, at one point, a thread where someone installed a JDM Horn and said it sounded better/was a super easy install.

 

@SpaceCoastBill I removed the OEM brackets from the horn and used it to mount the aftermarket horn.

 

I just ordered the horns.

Just remove the fog light trim to get to that horn?

There are 2 terminals on the new horn....what one goes where?

 

I installed a set of Hella Sharp Tones, they are ok, probably would go Supertones, if I were to do it over. Used the Grimmspeed Brotie bracket. No splicing, harness, used the feed off the second horn to activate and kept the lower horn intact and operational.

 

I went with Hella Supertones in the original stock positions (chamber near right fog light and on the radiator). The single Subaru wire is your hot lead and a ground jumper must be made from Hella to chassis. I don't recall if horn terminals were marked and no relay used. Sounds respectable now!

 

@SpaceCoastBill Trying to recall from two years ago, but my mechanic only removed the upper radiator shroud to access that horn from the top. With car up on hoist, lower right fog light panel was removed to access the hidden horn. I stayed with stock bracket and wiring but created a ground jumper of course.

 

So put the ground on the bolt that mounts the horn to the frame?

 

@SpaceCoastBill
The PIAA horns come with install wiring instructions that are pretty simple.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi6kb3Fj5DzAhUkmGoFHUtOA-MQFnoECAYQAQ&url=https%3A%2F%2Fwww.subaruforester.org%2Fattachments%2Fpiaa-sports-horns-pdf.2602%2F&usg=AOvVaw3h0FotETnw4V_Rtgq0U_sp

Installation A is what you’ll be looking to do. I grounded the horns directly to the vehicle via the horn mounting points.

 

Well since there is only one wire to the factory horn....it's pretty easy to know which one is positive!

 

That's right, a short lead from horn ground looped back to mounting bolt.

 

Didnt need the bracket. I just rotated the horn (the higher one) so i was facing down.

The lower one was already pointed the right direction.

 

I went to get the PIAA lights installed on my 21 Touring trim.

The higher horn was easier. Just remove the trim plugs and plastic cover over the radiator. There is enough room to get a wrench in there and get the bolt on the horn out. When I put in the PIAA horn I just rotated it until the horn was pointed down. I took the bottom wire on the horn and added and round wire terminal on it. I plugged the car horn wire into the top terminal on the horn. I got the bolt started and finished tightening it with a wrench.

The bottom horn was a bit more challenging. I could not get the fog light out so I went at it from the bottom. I didnt remove the bumper. I followed the instructions here to get access to the horn...

('19+) - 2020 - DIY ► LED Foglight Install!

After taking delivery of my 2020 Limited I changed my front grille to the all black sport grill - and also changed out the fog light covers to those from a premium. However, shortly after, I realized I didn't like the halogen fogs and LED headlights mixed together. I tried some LED bulbs in the...

www.subaruforester.org

Getting that bolt is challenging because of the angle. Once I got the wrench on it, it came right out. Again I put a round terminal on the connector and put it on the bottom terminal. Getting this bolt started with the washer and round terminal was definitely done by feel, and its at a hard angle. Maybe someone with longer arms might be able to get it easier.

Once that bolt got started, getting it tight was easy. It was already pointed down so I didnt need to change anything on the horn. I plugged the power cable on the top terminal and put the trim panel back together.

Worked great, not especially difficult.

 

Installed Piaa horns today. Both worked fine during test and after a few test runs, the one on passenger side stopped working. Swapped it with OEM horn and that worked. Swapped the OEM horn with Piaa horn and same thing happened. I used OEM wiring and grounded both horns properly, looping with fastening bolts. Any ideas? I have a 2021 Forester.