The horn not working dt250, have power to wire at horn . Should a horn sound if connected to a 6 volt battery to test horn?

It sounds like the relay you wired in for the air horn may have caused a problem with the electrical system in your 2003 GMC Sonoma. To fix the issue, you will need to locate the relay and rewire it back to its original configuration.
Here is a basic outline of the steps you can take to rewire the relay:

1. Locate the relay: The relay for the air horn should be located near the battery or in the engine compartment.
2. Identify the relay terminals: Relays typically have five terminals - a battery input, a switch input, a load, a ground, and a coil.
3. Disconnect the power: Before you begin rewiring the relay, make sure to disconnect the power to the vehicle to avoid any electrical hazards.
4. Remove the wires: Carefully remove the wires that you added to the relay for the air horn and LED light.
5. Return the original wiring: Reattach the original wiring to the relay, making sure to connect the wires to the correct terminals.
6. Test the system: Reconnect the power to the vehicle and test the electrical system to make sure that everything is working properly.

It is also possible that the relay is damaged, in that case you will need to replace it. It is advisable to refer to the vehicle's wiring diagram or consult a professional mechanic.

There are no worries about battery size if you are using a motorcycle horn, because a mobility scooter battery is 6 times larger than a motorcycle battery. A motorcycle battery just uses a simple button, but larger car twin horns use a relay. A 12 volt sounder is electronic, so no worries there. You could use a truck reversing sounder. Don't forget that they are not omnidirectional, so they need to be pointing forward.

https://www.google.com/search?q=horn+relay+wiring

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You have all the informations to find your problem. jump a wire on connector X4 G1 tan wire to ground and check X1 E5 with a test light or multimeter to see if there is a output, you should have 12 volts. If you dont have any voltage the horn relay is defective. I check in the shop manual and the relay come with the underhood fuse block.

Use a multi-meter set to dc 12v take the horn out of circuit and connect the positive end to the horn supply from the horn switch and the negative to an earth point on the frame. Press the horn button, do you see the meter jump up to 12v when you do this?

Yes - Replace the horn assembly. It's getting voltage but not sounding.

No - Suspect that the wiring or the horn switch is faulty.

isolate the battery. Disassemble the grip Disconnect the wires to the horn. Set the meter to continuity test. Put the probes on the terminals of the horn switch. press the switch. Do you see the meter on the Multi-meter kick?

Yes - suspect the wiring between the switch and the horn assembly.

No - With the 12V side of the switch isolated from ground reconnect the battery. Switch the multi-meter to DC Volts. Connect the positive probe to the supply side of the switch wire and ground the negative side. Does the meter kick to 12Volts?

Yes - I don't know what is wrong. possibly an intermittent fault.

No - You have no supply form the battery. Suspect the wiring loom from the battery to the switch especially where it goes from the frame to the handlebars. You could have a break there.

Not being smart but get a manual or youtube it. You need to remember that the air bag is located near the horn device. You can be hurt by the bag if it inflates.

Un plug horn connect horn to another 12 volt power source, if it works then the problem is the horn button located in the steering wheel assembley

if you take a test light and test all the fuses in the fuse box and if they are good then when pushing on the horn button you can usually hear the horn relay working(click).if it does then you need to check the horn itself.take a wire and run it from the battery positive cable and connect it to were the horn wire connects to the horn,it should blow(make sure of a good connection),if it does then it could be a dirty connection at the horn.if it doesn`t blow then the horn needs replacing.you can also use the test light and test for power at the horn wire at the horn itself to see if the horn is being feed power from the horn button to the horn.

Lift the hood of the truck. Locate the fuse box and lift the cover. Check the horn fuse listed on the cover of the fuse box. If the fuse is blown replace it. Have someone press the horn and listen for a faint click from the relay or swap the relay with another one with the same part number (IGN or AC) to test the relay. If you hear a faint click the horn switch on the steering wheel is good. If the horn works after swapping it with another, the relay is bad and you should order a new one. Remove the horn connector and check the voltage with a 12 volt lamp connected to the two wires or a volt meter when someone presses the horn switch. You can also directly wire the horn to the battery to see if it sounds. If it does not sound the horn is defective. If you do not have voltage check the black ground wire on the horn connector to see if it has zero ohms, or if you connect the 12 volt lamp from the black horn wire to the +12 of the battery the lamp should light. If not your ground wire is bad. I hope this helps you find your problem, but if you have any questions post a comment and I will answer your question.

hot wire the horn direct to the battery to check the horn. If it works check the relay if you know how to do that. A green wire should be there connected towards the steering column. Test the voltage output from that wire when someone presses the horn pad. If no readings shows on the volt meter the relay is at fault. If 12 volts show as a reading the horn contacts are bad

get two seperate wires and connect it to terminals of the horn then connect it directly to the battery and see if it will work. if not, then your horn is busted.