Ok, I have a 2001 xlt 3.0 v6 it has the factory installed remote locking system, my horn had been sounding sickly for a while, but I hadn't bothered looking into it, untill it finally stopped honking all together.....you can hear the relay clicking when I press on the horn, when I hit the keyless lock button, and when the alarm is triggered, but no beep, just a very muffled "hu hu" sound, I've checked the fuze/ relay box, I've checked the auxiliary relay under the dash. I have also checked the horn itself by connecting it directly to the battery, and all were fine.....however when I tested the leads on the horn connection plug, I was only receiving about 6.5V, can anyone tell me what to check/ where to look from here??? I need to get this fixed asap, again, all help is greatly appreciated! Thanks!

 

Try swapping the old leads with new ones. Its possible they are corroded

 

the horn grounds through the mounting bolt. i've had a lot of issues with mine not grounding well. try cleaning the metal.

 

The mounting bolt is the ground? There are two wires attached to the hookup, one blue and one black, I thought the black was the ground...

 

If your truck has the factory entry/alarm system the horn receives power from the central security module to the horns connector terminal 1 via a dark blue wire. Terminal 2 is the ground for the horns via a black wire to G105 located on the right inner finder panel.

You should have battery voltage (12V) on terminal 1 (the blue wire) when measured to chassis ground with the horn button pushed. Using an Ohm meter you should have .2 ohms between terminal 2 (the black wire) and chassis ground at all times.

 

So JJ what would you suggest I try? Check the leads at the CSM? Re-check the ground? What do you think?

 

on my 95 ground is the mount. sounds like newer years/other options change things a little.

 

Using a Volt Ohm Meter set to 12V disconnect the horn wiring connector and back probe the Dark Blue wire with the red probe. Connect the Black probe to the battery negative post. Press the horn button and watch the volt meter. If its within .5 volts of battery voltage I'd say the power supply side is good. If not, you'll need to located the Central Security Module and check the voltage output at the corresponding terminal there. If its still off, check fuse 11 (CJB dash) and fuse 8 & 33 (BJB under hood) for loose or bad connections. If there good you may have to replace the Central Security Module.

Next set your meter to Ohms and connect the red probe to the Black wire at the horn wiring connector and the black probe to the alternator housing or another known good ground point. If the meter reads greater than .2 ohm check G105 located on the right inner finder panel.

 

i think there must an issue with the alarm wiring or installation or some time its happen when the door lock sensor will not properly work so try to check that or take it in workshop if there is any problem with that sensor.

 

Glad I found this thread, seems to be perfect.. I am installing aftermarket horns and need to tap into the signal wire of the stock horns. From the harness above mine is the same, blue wire and a black wire.

If the blue is the 12v and the black is the ground, which one can I use to trigger another relay to make the new horns honk? IE: I just need the signal wire of the horn harness.

Would I be tapping into the blue wire then?

Thanks,
-Nigel

 

Yes, tap the blue wire and run it to terminal 85 of the relay and connect terminal 86 to ground. When you push the horn, the relay contacts will close connecting terminal 30 to terminal 87.

 

Perfect!! That worked exactly as it should. Now I have the two hella supertones behind the grill and the two factory horns by the passenger side!

I'll snap a pic shortly :-)

Thanks,
-Nigel

 

Installed... and Loud AF!

-Nigel