Chevy Silverado and GMC Sierra Forum banner
1 - 20 of 57 Posts

·
Registered
Joined
·
29 Posts
Discussion Starter · #1 ·
Hey folks, I'm new here.

So I just bought a 2004 Silverado 1500 5.3 Crew Cab Z71. 295,000 km on it.

As the title says, I'm having an issue where when the truck is running the horn will not stop blaring if I Honk it even a tiny bit. However, if the truck is not running, it usually only honks as long as I hold the horn in.

I already pulled the airbag off and checked the switch contacts, swapped the horn relay, swapped the horn fuse under the hood...

I'm pretty stumped on this one. Anyone else have the same problem?

The only aftermarket items I know about on the truck are a front and rear dash cam setup, and an aftermarket remote starter.

So, could this be an issue with the actual horn? Or would it be a wiring issue? I'm thinking a ground... but where? Or would it have a correlation to the aftermarket components I mentioned?

Any help will be greatly appreciated!
Thanks!
 

·
Registered
Joined
·
735 Posts
I think the circuit is fairly simple. Horn switch closes horn relay, horn makes noise. now the BCM also can trigger the horn, but I dont think that's your issue.

Sent from my SM-G998U using Tapatalk
 

·
Registered
Joined
·
131 Posts
Since you already replaced known good horn relay, so the problem is not relay itself.

Try this:

Let engine run, remove the horn relay, use a voltage meter checking relay solenoid contacts (#85 and #86 on the relay connects) volt, it should be zero before the horn button being pressed. Then, press and release the horn button, see the volt changes, it should change from 13V to 0.

Like your situation, if the volt stays 13V after the button being released, then the horn circuit has problem.


So I just bought a 2004 Silverado 1500 5.3 Crew Cab Z71. 295,000 km on it.

... when the truck is running the horn will not stop blaring if I Honk it even a tiny bit. However, if the truck is not running, it usually only honks as long as I hold the horn in.

I already pulled the airbag off and checked the switch contacts, swapped the horn relay, swapped the horn fuse under the hood...

Any help will be greatly appreciated!
Thanks!
 

·
Registered
Joined
·
131 Posts
For this case, there is nothing to do with Ground. As long as horn is honking, the Ground is good.

The aged horn itself could have problem, it could over draw high current, which causes relay contacts over heating and "sticky". Since you have 2 horns (Hi & Low tone), disconnect 1 horn first, see the result.


Ok, do you know offhand where the horn ground is located?
 

·
Registered
Joined
·
735 Posts
For this case, there is nothing to do with Ground. As long as horn is honking, the Ground is good.

The aged horn itself could have problem, it could over draw high current, which causes relay contacts over heating and "sticky". Since you have 2 horns (Hi & Low tone), disconnect 1 horn first, see the result.
Agreed No way a horn honks without completing the circuit.

Sent from my SM-G998U using Tapatalk
 

·
Registered
Joined
·
735 Posts
Since you already replaced known good horn relay, so the problem is not relay itself.

Try this:

Let engine run, remove the horn relay, use a voltage meter checking relay solenoid contacts (#85 and #86 on the relay connects) volt, it should be zero before the horn button being pressed. Then, press and release the horn button, see the volt changes, it should change from 13V to 0.

Like your situation, if the volt stays 13V after the button being released, then the horn circuit has problem.
If your getting voltage to the relay, it's likely the switch is stuck.

Sent from my SM-G998U using Tapatalk
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #10 ·
Hey guys, been pretty busy... but got back to it today.

So, I'm going to replace the battery on my multimeter today so I can get some proper voltage readings.

When I pulled the relay, numbers 86 and 87 I believe both showed positive voltage, all the time. With 86 going a bit brighter when horn was pressed.(Again, will be more clear with a multimeter.) The other two showed ground.

Another observation, when I put my test light on the contact under the steering wheel, and touched the other end to a ground, the horn would stay on after pressing until I broke the connection with the test light. The test light bridging the steering wheel contact to a ground would NOT make the horn sound, (as a peice of wire did) but it would keep the horn going after I pressed it. (With the truck off. When the engine is running, the horn stays on when pressed all the time.)

So, I'm theorizing that I have a partial short or something somewhere, and when the engine is running (alternator bringing system up to 14 volts) there I enough to keep it going???

I'm not great with electronics, but I kinda have to learn now.😆 I'm trying to get the truck safetied so I can use it for work, but I need the horn to work....

Thanks for all the input so far.
 

·
Registered
Joined
·
735 Posts
Hey guys, been pretty busy... but got back to it today.

So, I'm going to replace the battery on my multimeter today so I can get some proper voltage readings.

When I pulled the relay, numbers 86 and 87 I believe both showed positive voltage, all the time. With 86 going a bit brighter when horn was pressed.(Again, will be more clear with a multimeter.) The other two showed ground.

Another observation, when I put my test light on the contact under the steering wheel, and touched the other end to a ground, the horn would stay on after pressing until I broke the connection with the test light. The test light bridging the steering wheel contact to a ground would NOT make the horn sound, (as a peice of wire did) but it would keep the horn going after I pressed it. (With the truck off. When the engine is running, the horn stays on when pressed all the time.)

So, I'm theorizing that I have a partial short or something somewhere, and when the engine is running (alternator bringing system up to 14 volts) there I enough to keep it going???

I'm not great with electronics, but I kinda have to learn now. I'm trying to get the truck safetied so I can use it for work, but I need the horn to work....

Thanks for all the input so far.
The horn switch typically switches the (-) side of the horn relay. Your light bulb resistance must have prevented enough current to switch the relay, but enough to hold it. Inrush vs holding current. The horn circuit is pretty simple, and similar across many makes and models. I'm pretty certain the problem is the horn switch. I would've replaced it by now to see if it fixes the issue. I of course would've checked resistance from the negative side of the relay to ground to make sure you don't have a short.

Sent from my SM-S908U using Tapatalk
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #12 ·
The horn switch is behind the steering wheel, right? Because the switch back there does not stick. I have watched it multiple times.

The other variable that I'm looking at is the truck has an aftermarket remote starter, could this be an issue?
 

·
Registered
Joined
·
735 Posts
The horn switch is behind the steering wheel, right? Because the switch back there does not stick. I have watched it multiple times.

The other variable that I'm looking at is the truck has an aftermarket remote starter, could this be an issue?
I can't think of anything else that makes a horn continue to honk after pressing the steering wheel?

Sent from my SM-S908U using Tapatalk
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #18 ·
Let engine run, remove the horn relay, use a voltage meter checking relay solenoid contacts (#85 and #86 on the relay connects) volt, it should be zero before the horn button being pressed. Then, press and release the horn button, see the volt changes, it should change from 13V to 0.
Are you sure? I'm getting constantly between 10-12 volts there.
 
1 - 20 of 57 Posts
Top