Horn Out - Its not the fuse, relay, or clock spring - frustrated!

So the same as many others here. One day the horn stopped working. Easy to diagnose right?
I mean there are tons of posts on the fuses, relay, and clockspring.

Checked fuse, relay, and replaced the clockspring. Horn still does not work.

Lets back up to what I do have and what I saw.
I do have the horn work on the panic button (so the horns work).
I do not have the horn on the steering wheel press.
The 10a fuse is good - no issues.
The relay is good (just changed AND works on panic).

Back up a little further and when I first noticed the horn wasn't working, I checked the relay and it was melted a bit on one side (photo attached). Replaced the relay and the horn still did not work. Checked fuses (good) and changed clockspring. Nothing.

Has anyone seen this before?
Maybe a wire that saw too much current and melted upstream when the relay went (and melted)?

Any ideas would be welcomed. We are so frustrated.

Thanks.

 

That’s not a OEM Toyota relay. Whatever that relay is for, it’s something somebody added.

 

That someone is me - I added Hella Supertones years ago. They worked fine until this...

 

First hot wire the horns and see if they actually work. If lead hot to horn when you push the button check the ground. All I got for you.

 

Have you tried checking and cleaning the contacts for the horn switch in the steering wheel?

 

Yeah, will do that this morning with my Fluke. My guess though is that since it comes on for panic button on keyboard, the relay works fine. This should let me see if I'm getting anything from the horn directly.

 

Its funny, just had it off for clockspring last night. I would just have expected if it was that, I would see intermittent. Will check regardless. Thanks.

 

OK, I'll bite.

Volt Ohm meter; best tool in the box for issues like this.

I will approach this somewhat differently than the shotgun approach that you have used to date; this based on what you have posted. I could be wrong but it sounds like you pulled the fuse and looked at it and then went forward with more of your visual examination and found the damaged relay. The quoted post is the first mention of your using a volt ohm meter to isolate the problem.

So, the first question to ask is if there is -12VDC at the horn when the horn actuator on the steering wheel is depressed. Without knowing the answer to this you are not applying any scientific method to isolating the location of the problem.

But, having said that, the aftermarket relay damage is worrying. I cannot help but wonder what gauge wire was used for the horns you installed.

And, I cannot help but wonder if the original horns are also in the circuit; you provide no information as to what was done previously which makes doing any further investigation impossible because we do not have sufficient data to make any determinations as to where we should concentrate our efforts in an attempt to isolate/locate the problem.

So, we need more information about the configuration of the horn system in you vehicle before we can do much more testing to isolate the problem.

Regards,

Jim

 

Since the panic works it should be from BECU towards the steering wheel ground.

 

Jim,

You were correct. I pulled the fuse, looked at it, but never tested the circuit.

As for the relay issue. That again was my fault, as I mounted it connection side up, which likely caused it to fill with moisture and short (since rectified).

thanks for the thorough response. I'll grab additional info and some pics and post it back.

/r

 

Thanks, I'll check for voltages and see if I find it between there.

 

For others...
https://www.bmotorsports.com/shop/product_info.php/products_id/4550

 

I love this!

 

It sounds like you just visually inspected the fuse. I'd grab a known good fuse and swap it in to eliminate that as a problem. I've seen fuses appear fine but be bad.

 

Check on that. Exactly what I did. Rain here today, but plan to check fuses again with multimeter.

 

Bummer, I always hope for the simple solution. Good luck in the hunt.

 

OK

The wiring diagram is a good place to start. But, it does not show what you installed in the horn circuit; this based on your statement above, that you installed, "Hella Supertones years ago.".

So, next we need to see how those are wired and it would be nice to know what gauge wire you used between the battery and the relay and between the relay and the Hella horns.

It does no good to make assumptions about what you did because we would be shooting in the dark and that would be a complete waste of time.

So, please provide that info so we can see the overall picture of how things are wired. I continue to be concerned about that relay. That was caused by a lot of heat and wiring not capable of carrying the amperage of the Hella horns could well be the cause; it could lead to an engine compartment fire which is something you definitely do not want to encounter.

Once we have the wiring diagram for the entire horn circuitry we can decide how we want to go about trouble shoring the problem. The entire objective here is to keep that number of "things" that we have to open up to a minimum in our search for the problem.

I have no idea what you electrical background is; it is all too easy to waste a lot of time and effort chasing problems if you do not approach it with some sort of "scientific method". By this I mean that we need to look at the overall circuitry and decide what and where we want to test.

By way of an example I offer the following that was used to train telephone installer/repair people.

Phone line are much like the horn circuit. Two wires, one that has battery on it and the other that will have a ground on it.

In between the two ends that have the voltage on one wire and the ground on the other there is a switch.

In the case of the truck it is on the steering wheel and it is something we push to complete the circuit so the voltage goes through the horn seeking the ground. When the voltage meets the ground that completes the circuit and the horn makes its noise.

In the case of the telephone when you lift the handset from the cradle of the phone, the switch that was open when the buttons that the handset kept depressed were released will close. By the time you have the handset up to your ear you would hear what is called dial tone. All this because the voltage was able to pass through the telephone set and back to the phone company office from which the voltage came and the circuit to ground was completed.

Just like the horn.

In the case of the truck, the wiring is all in one place.

In the case of the telephone the wiring runs for 12 miles from the phone company office to your house, and back.

So, if you were the telephone guy you would have 12 miles of cable to check to locate the open wire or false ground on the wire that is keeping the phone from working. Just to keep it simple we will say there are 100 telephone poles between the phone company office and your house.

What is the MAXIMUM number of poles that you will have to climb in order to locate the problem?

We all know that the truck has connectors between the horn switch and the ground at the other side of the horn for the wiring.

The same is true for the telephone line; these are called access points.

So, we know that our wires in both cases are not a single piece of copper going from the battery to the ground.

Without the wiring diagram we have no idea how many connectors/access points there are in the circuit. Before we start climbing poles we need to know not only how many access points there are; we also need to know where they are; which poles they are on.

Same for the truck.

Back to the question about the MAXIMUM number of poles that you would need to climb. Again, to keep our example simple lets assume that each of the 100 poles is also an access point. You now have sufficient information to answer the question. If you came up with an answer prior to knowing the number of access points you were guessing; that is/was a complete waste of time and energy.

Figured it out?

The answer is very simple. Davide by two.

First we go the end point which is the telephone itself to see if there is dial tone. If not we know the problem could be in lots of places. So we must begin to eliminate the places the problem can be. Next we go to the location at the house were the wiring from the telephone pole come into the house. If there is no dial tone there we know the problem is not in the house and we now can attack the telephone poles themselves.

So 100 telephone poles decided by two equals 50 telephone poles. Go to the middle pole in the span and you will know if the problem is between the house and that point or the phone company office and that point.

Whichever it is, devide by two which means going to pole number 25 in the direction indicated d(house/office). Which direction is the problem?

Again, decide by two. And do it again. And again. And again.

Worst case you will have to climb 7 poles before you will have isolated the problem.

The same scientific method" should be applied to locating the problem with your horn.

Once you have isolated the segment of cable with the problem you now can go look for the cause. In the case of the telephone, it turns out that we are in the country and had to walk a mile of cable before we were able to spot the bullet hole in the cable that is causing the problem.

In the case of your truck I will not be surprised about anything we find because we have a lot to choose from given the additional equipment you installed.

I look forward to further adventures in isolating the problem with your horn; or is it horns? You never really did give us much info about the Hella horns and we have no idea if they are working or not. Or if they are even wired such that they sound when the stock horn is actuated.

Regards,

Jim

 

Ain't nobody reading all that... Wall of text.

 

Sounds like you may have forgot to reconnect the ground in the steering wheel when you replaced the spiral cable.

 

And, ignorance is bliss!