Where is the horn relay?

If I understand the manual correctly, it is not very clear, it is in the rectangular box screwed to the cowl in the engine comparment near the middle of the compartment.

 

The HORN relay is located within a four-relay module installed within the main relay/fuse box next to the inverter. That module is labeled Unit C.

However, I agree with northwichita's post in this forum, which states that since you have electrical problems with the horns and the airbags, it seems likely that the spiral cable within the steering wheel hub is the problem.

 

Hi Ed,

You are right. I took a look at my 2004 and relay block C is the one containing the horn relay. The 2004 Toyota electrical wiring diagram does not label the two relay blocks, while the 2006 version confuses B and C.

If you are going to pry out the relay block to gain access to the terminals, then you can also insert a jump between the switched terminals to confirm that the wiring to the horns, and the horns themselves, are good. Then, you can use an ohmmeter to see whether the relay terminal that connects to the horn switch shows continuity to ground, when you have a helper depress the horn switch. If those two tests are good then the relay is bad.

 

I thought I'd horn in, and mention that my 2004 Prius (269K miles and going strong) has only one horn now. When new, it had a weak two-tone honk; now it's a weaker one-tone peep. I thought it might be merely that a wire is off one horn, but didn't know where to look. I assume that both horns have the same fuse and relay.

 

Ken, the same thing happened to me on my 2009 Prius. Then even the weaker, higher-pitched one tone stopped working. When that happened I finally started checking things out. The fuse was good, 10A, I swapped it with the hazard lights and they still worked with the horns fuse. Next I looked around under the front of the hood. I found the horns and lo and behold, on both, the wire had somehow come loose from the connector it was attached to, which then plugs into the horn. In other words, the connectors were still as they should be, but the wires were out of the connector. Both of these must have happened while I was using the horn, so someone didn't do this. In fact, in each instance one of the horns had stopped working, I had been using them.

Anyway, I was able to remove the horns, disassemble the connectors. Then solder a longer length of wire onto the wires under the hood, (so I had some length to work with). I then was able to connect and solder the other end of those wires onto the connector. I put heat shrink over both joints (where the original wire and my pigtails meet), as well as over the end where I connected my pigtails to the connector plug. Then I plugged in the connectors and remounted the horns and now they both work.

I came here to Prius Chat to do a search and see if a lot of other people have had a similar problem.

 

QuiGonJohn wrote: I was able to remove the horns, disassemble the connectors. Then solder a longer length of wire onto the wires under the hood, (so I had some length to work with). I then was able to connect and solder the other end of those wires onto the connector. I put heat shrink over both joints (where the original wire and my pigtails meet), as well as over the end where I connected my pigtails to the connector plug. Then I plugged in the connectors and remounted the horns and now they both work. I came here to Prius Chat to do a search and see if a lot of other people have had a similar problem.​

John, thanks for the answer. This helped me find a small black wire that was broken off from the connector to the middle horn of my 2007 Prius. There doesn't appear to be any wire sticking out of the connector. I've never attempted anything like this, so wonder if you can explain the procedure? I assume I must take the metal piece off so I can get at the horn, then attach a new length on and solder that to the connector...?
1) Is it obvious how to disassemble the connector? I assume you need to do that in order to solder the wire onto it? Is there a wire in the connector where you can pigtail your additional wire length?
2) What kind of wire and is that something I can get at Home Depot? Also, any recommendation for soldering tool?
3) Are you just twisting the wire together where you are adding the extra length, and then just solder in the connector?
4) I assume I can get heat shrink at a hardware store. Can you heat it with a hot glue gun or do you need a special tool?
Thanks much!!
andrew​

 

I have a 2008 Prius and I am having problems finding the horn relay...and I've looked at the infamous Block C...and it does have the horn fuse (which is in tact)...but it does not contain any Relay. Anybody able to give me a definitive answer on it's location? I know it exists...they sell one for the car. I'll make a nice youtube video to show the world where it is if I ever find it. Thanks. -e

 

Block C contains four relays in the one unit.

 

Have You Cod reley Horn per Prius 2011?

 

Hi Patrick, can you explain to me how to pull out (pry) the relay cover so I can have access to the switch terminals. I need to hookup directly a temporary horn switch button until I will fix the steering wheel spiral. Thanks

 

Ok,Patrick, my car is a Prius C. I succeeded to pull out the relays cover but instead of hooking up the new horn switch to the relay can I just connect it directly to the red battery contact which is in the black triangular box with relays near the hybrid inverter on the right side of the engine compartment?

 

Hey Patrick, I succeeded to pull out the black plastic cover signed w.C. My question is: instead of connecting the temporary horn switch to the horn relay, can I connect it directly to the red battery cap located in the black triangular fuse box near the hybrid inverter? This fuse box has a metal connector coming from the battery positive pole. This connector is used for emergency engine start up when pulling cables from another car battery.

 

You could connect the horn switch to the dedicated positive jumpstart terminal. However you also need to include an inline fuse of the appropriate current rating. 5A probably is sufficient for the horn.

 

Hi there, new to the forum and new used proud Prius owner of a 2012 V

I have been trying to figure out why my horn doesn't work after 5 months of having this car just found out the horn does not work,
after reading these forums for the last few weeks and going over everything I am still stuck, I am pretty sure its the unit C relay but for the life of me I have no idea how to get the cover off or how to take the unit out to buy a replacement.

Could you please please share with the forum how to pull out the relay and the cover and even where the fuse for the horn is.

Thank you