Horn Problem

[BigredTEX]

Need some help from the tech experts. My horn has stopped working. I initially noticed it several weeks ago. Checked the 10A fuse and found it OK. Pulled the relay and swapped it with an identical adjacent relay and the horn worked. Replaced the original relay and the horn continued to work, so chalked it up to a sticky relay and forgot about it.....until I tried to use the horn yesterday - nothing.

I've searched the forum and found several helpful threads, but none that address my problem based on the troubleshooting I've done. I found a wiring diagram posted by [MENTION=83083]rigtec[/MENTION] that was very helpful that points me in two different directions.

I'll summarize troubleshooting efforts:
- 10A fuse is still good.
- Relay checks out when energized by direct connection to the battery.
- I DO NOT get continuity to ground at the relay coil socket in the fuse box when pressing the horn pad. This could indicate a bad horn switch.
- If I jump 12v to the relay to energize the horn circuit the mechanical horns do not honk, but the alarm horn, located below the air filter box does honk (how many of you knew there is a 3rd horn under the hood?).
- jumping 12v directly across the switched relay leads produces the same results, mechanical horns do not honk but alarm horn does honk. On the surface this could indicate a fault in the circuit between the relay and the mechanical horns. I have not checked continuity between the relay and the horns so cannot definitively say there is a fault in the circuit but jumping 12v directly to each of the two horns gets a honk.
- Press the panic button on the key and the mechanical horns honk. Based on the wiring diagram posted by [MENTION=83083]rigtec[/MENTION], this would indicate there is NOT a fault in the horn circuit between the body control module and the horns, but there could still be a fault between the relay and the module based on the testing I've done so far (need a more detailed diagram showing connectors and locations that I can probe to be sure).

So here's where I could use some help. 1st, how do I get the horn pad off the steering wheel to check the switch and/or spiral cable? If it's like most things with Toyota interiors I would just grab and yank, but want to be sure before I do that. 2nd, does anyone have any other ideas of what and where to check?

Thanks in advance for your help.

 

[rwrobs777]

If I were you I'd REPLACE that relay with OEM since it had worked fine after it was swapped out...let me know how it works out...I'm usually in the C5 Corvette Forum as a Technical Advisor but since I have a 2016 4 Runner I occasionally stop by here...these trucks have very few issues...we have a LOT of electrical issues with these C5 Corvettes...LOL !!!...I looked in my Mitchell wiring diagrams for my '16 and I don't see a "3rd" horn...where is it located ??...so relay info:
All of these relays have 2 powers feeds...a load and control...make sure you see both feeds with 12 volt test light...this circuit is "hot at all times" !!...now take your test light connected to battery POSITIVE...C7 (in the wiring diagram) when probed at the relay should make the test light illuminate when the horn pad is depressed...now if you jump the load side feed to C8 both horns (as per my 2016 wiring) should sound !!

 

[BigredTEX]

Thanks for the response. The relay is the original and it checks out. I was surprised the horns honk using the panic button but will not honk if I jump 12v to the downstream side of the relay, but the alarm horn will honk. This makes no sense to me. However, since the horns honk via the panic button it seems to prove the circuit is good downstream, leaving the circuit from the horn button to the relay in question.

If anyone can tell me the best way to remove the horn as I would really appreciate it.

 

[rigtec]

"Need some help from the tech experts. My horn has stopped working. I initially noticed it several weeks ago. Checked the 10A fuse and found it OK. Pulled the relay and swapped it with an identical adjacent relay and the horn worked. Replaced the original relay and the horn continued to work, so chalked it up to a sticky relay and forgot about it.....until I tried to use the horn yesterday - nothing.

I've searched the forum and found several helpful threads, but none that address my problem based on the troubleshooting I've done. I found a wiring diagram posted by [MENTION=83083]rigtec[/MENTION] that was very helpful that points me in two different directions..."

Hi BigredTEX,

I read your post! Based on the diagram, the Horn Sounders have two different "Ground-triggers" (Negitive/Ground-side switching). The first is the Horn-pad on the steering wheel that supplies the ground circuit for the horn ONLY. The second is the Main body ECU Compu network that supplies the ground circuit when the alarm is triggered!

Now I read the check list that you've posted; "Very good diagnostic approach" Kudos! But based on what I've read, the horns will blow by hitting the "Panic-button"; which tells me that the relay coil is getting a ground source from the Main body ECU when using the panic button!

But... is NOT getting the required relay coil GND through the Spiral Cable Clock-Spring in the steering wheel; here's that diagram to offer a visual with this trouble:

As shown in the above diagram, the "Main body ECU" supplies the GND to the relay coil for the alarm/panic-button to trigger the mechanical horns to operate! But when the horn pad is pressed, there's NOT a GND to the relay coil to trigger the mechanical horns, you follow(?)! The Spiral cables do break on occasion, due to the nature of their function e.g., bending, turning, stretching...etc!

The new "Clock-spring spirals" can be had cheaply, if you DON'T order them from Toyota dealership parts dept! I saw them on ebay... FREE S&H for $31.00 bucks:

Oem Spiral Cable Clock Spring 84306-60080 For Toyota 4Runner Lexus GX470 LX470US | eBay

You may find them even cheaper than that if you spend the time! To remove the horn pad, there are two screws on the back-side of the steering wheel, just remove those and the pad comes right off! There's also plenty of threads in our massive library; even some with pictures, cuz this is a routine replacement part!

Sorry for my delayed reply; needed to get away from my laptop and spend more quality time with the fam over the holiday! Please let us know how you make out with this issue; it'll make things a lil' easier for the next guy/gal having similar troubles! 'Best to you',

rig, cheers!

 

[BigredTEX]

Than you [MENTION=83083]rigtec[/MENTION], for the confirmation of where the problem is and where to get the part! The truck is for sale and I don’t feel it would be ethical to sell it with a known problem, regardless of how minor.

 

[rigtec]

Than you [MENTION=83083]rigtec[/MENTION], for the confirmation of where the problem is and where to get the part! The truck is for sale and I don’t feel it would be ethical to sell it with a known problem, regardless of how minor.

Hi BigredTEX,

You're a good man BigredTEX! Some would've... just passed the problem to the next buyer; regardless of how small! Also your description of the trouble included sooo much detail that you already had the issue licked... nothing for me to do here! :noidea:

Before you remove the SW Horn-pad, be sure to disconnect the NEG battery cable 1st, as there's an SRS (Airbag) module just below the hornpad; which will cause N/P to move out of the way if needed... you're not the 1st to replace the spiral cable and Surely won't be the last!

'Best tou you',

rig, Cheers!

 

[arthurm]

I just started having a horn issue: steering wheel center on and slightly off the horn does not work. Turn the wheel a little more left or right and it works. No other issues with turn signals, cruise control, etc..

So, I assume it's the clock switch until I came upon this video:

2002 Toyota Sequoia clock spring bad, NOT!

https://www.youtube.com/watch?v=XUXv6Hzyb9g

It describes a loss of ground in the bearing aroung the steering wheel shaft. A simple cleaning with Deoxit and some dielectric grease solved the same issue I have. Granted it's for a different model and year but it should be relevant and as a first test before replacing the switch.

Questions:

1. To avoid losing all stored data (radio, bluetooth, etc..) is there a fuse to disconnect just the airbag or must I disconnect the battery entirely?

2. A puller is not required for the 5th gen's steering wheel, correct?

 

[arthurm]

BigredTEX: which part number did you purchase?

For my 2013 Trail (non JBL), all Toyota part sites show part number 8430735010, only available through dealers at over $300!