Is there a Horn relay in my truck ?

[gpintler]

My horn started going off the other day. I pulled the fuse to get it to turn off. Because I am an (old) guy I thought that the relay has gone bad, but when I pull the cover to the fuse box, I can not find a relay labeled HORN. I did a bit of reading an found somethings about a FCM module. Somebody please tell me that they did not substitute a $10 relay with a $150 Front Control Module.

 

[seafish]

My horn started going off the other day. I pulled the fuse to get it to turn off… I did a bit of reading an found somethings about a FCM module. Somebody please tell me that they did not substitute a $10 relay with a $150 Front Control Module.

Of course they did.

It's also important to know that the horn is switched by completing the ground, and NOT the hot wire, so you should check the wiring at the horn top look for an inadvertent bare wire to frame. That is actually easiest to do by removing the drivers side wheel well liner.

That said, the year of your truck, and more details about how and when it started honking, and if it was continuous or intermittent honking, would definitely help diagnose the issue better.

 

[gpintler]

ok more details to help you guys help me -- 2004 2500. My horn beeped 4 time with in 20 minutes. I thought it was 1 of my friends installing his air horn kit. Walked out of the house, the truck beep 1 more time and then locked on. I than opened the hood and pulled the fuse. It was been cold here in Idaho and because this is a 20 year old truck I was going to start by disconnecting the FCM and cleaning the contacts.

 

[gpintler]

I think I found my problem. I do not drive my truck much in the winter. Last time I drove it was hunting [10-23-24]. I went to go start it today, and it was dead. 1 battery showing 8.9 volts and the other showing 9.1 volts. This could be the cause of the problem. The Mopar batteries were purchased 2-24-17. they may have hit their service life.

 

[Ozymandias]

Yeah, weak batterys cause all kinds of funny stuff.

 

[seafish]

weak batterys cause all kinds of funny stuff.

The low voltage definitely can confuse the 1's and 0's that the various modules rely on to make an operative decision…it kind of makes the ones look more like zeroes and the zeroes look negative numbers

 

[gpintler]

I have found that the Horn relay is stuck on. I can't find the horn relay, but I am looking for this small 1 inch cube. Now I am thinking that it is part of the Front Control Module. Can somebody tell me where the the FCM is located in my truck.
(2004 4door 8ft box 4X4 SRW)

 

[Ozymandias]

Adjacent to the fuse box, hidden under the fender.
There are no mechanical parts involved, it is an all electronic device, not serviceable by the user.