Horn Not Working on PPV, My Diagnosis Thus Far (Actual Horn Unit Works)

[battlewagon]

Alright boys and gals, I have a 2013 Police Tahoe (PPV). Great ride, but horn doesn't and has never worked. I am in LE and have owned a few personal PPVs, so it is very very common for the horn to not work when you press the steering wheel in, as the wires often get cut in police equipment removal; sometimes they are disabled right from the get go when police equipment is installed.

At this point in time, I have determined the following:

The horn itself is good. Used a wire to jump power straight from the battery to fuse 29 (HORN), and the horn sounds off.

From what I understand, the sequence of events is as follows: Press horn, horn switch > wire > BCM > wire > under hood fuse box > wire > horn sounds.

The signal is NOT reaching the fuse box. When I use a multimeter and ground it, and place the positive probe on the fuse and press the horn, no power is registered at the fuse. When I do this on my Suburban, which has the same setup, power registers on the multimeter (and the horn sounds off). So to me, there is an issue between the horn switch (steering wheel) and the fuse box.

If I am correct, the issue can only be one of these:

Horn switch (steering wheel), or something related to it, clockspring, etc.

Wire cut between horn switch and BCM, or between BCM and fuse box.

BCM itself.

So...how can I test these and eliminate? I wanted to manually jump the wire running from the horn switch/clockspring assembly straight to the fuse box to see if that makes the horn sound off. To be honest, if it does, I will just leave it like that, and my problem is fixed, since I never use the horn ever anyways. I am just preparing to sell the truck, and while 99% of people don't test the horn on a test drive, I don't want to sell it to an unsuspecting buyer without a horn.

Something that will help me achieve that is a diagram or wire labeling that tells me which wire leaving the steering wheel is for the horn trigger. I have read on other years on other forums that it is a tan wire. When I get my head in the impossible position to look up back towards the wheel from under the dash, there are multiple tan wires.


Any help is appreciated, thank you.

 

[YukonandtheHOE]

Hope this helps, brown plug on the bcm pin 18 should be direct from the clock spring connection.

 

[battlewagon]

Hope this helps, brown plug on the bcm pin 18 should be direct from the clock spring connection.

Thanks, I know the BCM is somewhere to the left of the steering column, but I cant really see it under the dash. I guess I will remove the knee plastic under the wheel to try to get acesss and tap direct.

Any other advice I can go into the job with after work today is much appreciated!

 

[YukonandtheHOE]

Thanks, I know the BCM is somewhere to the left of the steering column, but I cant really see it under the dash. I guess I will remove the knee plastic under the wheel to try to get acesss and tap direct.

Any other advice I can go into the job with after work today is much appreciated!

Yup pull the bolster and the bcm is right their. Depending on what kind of test equipment you have... take a test light with a needle probe on it, hook the light to 12v and probe the tan wire on the Brown plug pin #18 when you hit the horn button the test light will light up if it has continuity. If your not comfortable isolating the #18 pin with the system energized, unhook the battery and pull the brown plug off the bcm it should be numbered. If not you will have to count pins top left is #1.

 

[YukonandtheHOE]

Also if you do find out that you have continuity their that means the BCM has the horn tuned out, just clip the wire off the plug, extend it for out to the under hood fuse center. Pull the panel up find the horn relay trigger wire and connect it up. Honkhonk lol

I do alot of Remote Starts lol

 

[battlewagon]

View attachment 70301 Hope this helps, brown plug on the bcm pin 18 should be direct from the clock spring connection.

Also if you do find out that you have continuity their that means the BCM has the horn tuned out, just clip the wire off the plug, extend it for out to the under hood fuse center. Pull the panel up find the horn relay trigger wire and connect it up. Honkhonk lol

I do alot of Remote Starts lol

People like you are why people come back to this forum. Excellent help along with the first reply. Thank you all so far, anything else you all have, keep it coming. Good resource for future Police PPV buyers.

 

[battlewagon]

Even with knee bolster removed, the BCM plugs aren't any more accessible. I cant even disconnect the tan plug from the receiving harness. I see the lock icon on it and depress the tabs on the side but cant get it to come off. I found a tan wire running right out of the steering wheel to the column, but there is also a tan with a black line wire. im afraid to tap it and then jump it with power to see if it works, only to have the wrong wire and fry some module because I jumped a module straight from the battery/fuse box

 

[YukonandtheHOE]

Even with knee bolster removed, the BCM plugs aren't any more accessible. I cant even disconnect the tan plug from the receiving harness. I see the lock icon on it and depress the tabs on the side but cant get it to come off. I found a tan wire running right out of the steering wheel to the column, but there is also a tan with a black line wire. im afraid to tap it and then jump it with power to see if it works, only to have the wrong wire and fry some module because I jumped a module straight from the battery/fuse box

I dident say it would be easy!lol

The tan wire at in the column should be it.

Do not apply power to any circuits, you will fry the BCM!
95% of the circuits are ground in Low current systems. What you want to do is have your testlight hooked to power and carefully poke through the conduit, pressing the horn will make the test light light up, confirming that the clock spring is passing the ground from the horn button down the column.

 

[battlewagon]

I dident say it would be easy!lol

The tan wire at in the column should be it.

Do not apply power to any circuits, you will fry the BCM!
95% of the circuits are ground in Low current systems. What you want to do is have your testlight hooked to power and carefully poke through the conduit, pressing the horn will make the test light light up, confirming that the clock spring is passing the ground from the horn button down the column.

Ten four, I meant to buy a test light on my way home yesterday, but forgot. My multimeter can test for continuity, but that function doesn't seem to be working.

So with a test light, if we get confirmation, I can cut the wire right there at the harness leading out of the clockspring assembly, and run that to the fuse box, bypassing the BCM, and that should work? Just want to confirm before I start cutting.

 

[YukonandtheHOE]

You betcha! Just find the wire that makes the tester light up with the horn and run her out to the relay like stated before!