Horn not working

[MisterB]

Well, if you followed my other thread, I finally got my heater working. Now, on to fixing the horn.

The truck had a cheesy aftermarket steering wheel on it, and the horn did not work at all. I found a nice factory wheel with all the horn parts and installed it. I can tell the metal plunger on top of the spring just behind the steering wheel is getting power, because it lightly sparks when making contact with the wheel during installation. The weird thing though is at that point, generally the horn would be honking like crazy, but it wasn't. I removed both headlight bezels to give me access to the horn on the left and the horn in the right. Discovered the left horn was unplugged from power. Upon further inspection, the tab on the horn for the power connecter to slip on was gone. So, I bought two identical horns off a truck like mine at the yard (I bought two so I'd have a backup in case one of them was broken). Anyway, cleaned the contacts on it, as well as the right horn, plugged everything in and tried honking the horn. Nothing. Swapped the left horn for the spair I got just in case. Tried honking the horn. Nothing.

My fuse should be fine, because I checked it the other day. Maybe I'll look again just to be sure something new didn't blow it. Other than that, what else should I check?

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[MisterB]

Fixed it! It was the horn relay that is up above the fuseblock.

I bought a new one, and it's a thing of beauty hearing those horns come to life. It's actually a really nice clean tone.

I'm glad I can go back to honking at idiots that don't know how to drive

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[chengny]

Well, if you followed my other thread, I finally got my heater working. Now, on to fixing the horn.

The truck had a cheesy aftermarket steering wheel on it, and the horn did not work at all. I found a nice factory wheel with all the horn parts and installed it. I can tell the metal plunger on top of the spring just behind the steering wheel is getting power, because it lightly sparks when making contact with the wheel during installation. The weird thing though is at that point, generally the horn would be honking like crazy, but it wasn't. I removed both headlight bezels to give me access to the horn on the left and the horn in the right. Discovered the left horn was unplugged from power. Upon further inspection, the tab on the horn for the power connecter to slip on was gone. So, I bought two identical horns off a truck like mine at the yard (I bought two so I'd have a backup in case one of them was broken). Anyway, cleaned the contacts on it, as well as the right horn, plugged everything in and tried honking the horn. Nothing. Swapped the left horn for the spair I got just in case. Tried honking the horn. Nothing.

My fuse should be fine, because I checked it the other day. Maybe I'll look again just to be sure something new didn't blow it. Other than that, what else should I check?

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The power supply to the horns doesn't pass through the switch in the steering wheel. Operation of the horns is controlled by the horn relay. Pressing the horn button just creates a path to ground for the relay's coil. That causes the coil to pull in and close the contacts on the power side of the relay. Only then is power sent to the horns.

Both the coil and the line side (think of that as the inlet side) of the contacts are supplied by a common lead (ORN 240A) that is served by the HRN-DM fuse. The load side (think outlet side) of the main contacts is run out to the horns on a separate lead (DK GRN 29). The black lead (BLK 28) connects to the third and final terminal - which is then run into the cab and up to the switch/button in the steering wheel.

BTW - if your HRN DM fuse was blown you would likely be aware of that because you would not have a dome light (or a clock if so equipped).

I would start with the relay:

Here's some pics its hard to find there's two levers you lift away from the relay
its hanging from the harness its not in the fuse block.

It is GM (Delco) P/N 344813. Available anywhere.

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[chengny]

File the post above under too little too late.