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Discussion Starter #1
I had my small shop-vac sitting in the drivers side floor area while I was vacumming today when all of the sudden the horn started blowing non-stop. I turned off the vacum and grabbed the keys and started trying to turn off what I thought was the alarm on the truck. No luck. I put the key in the ignition, turned it to on, horn still blowing. I then started the truck. Nothing changed. The horn finally stoped. I turned the vacum back on, same thing. Horn going nuts. Moved the vacum to the rear compartment thinking that there might be some sort of glass breakage sensor installed from the factory that was being tripped by the noise of the vacum. No problem after that. I do not have any thing other than the factory equipment on my truck, no after mkt. alarm. Any ideas what might have been causing this?
 

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Does the horn blow steady, like hoooooooooooooooooooooooonk or honk pause honk pause.
 

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Discussion Starter #3
Steady. Non-stop.
 

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ooooooh weeeeeeee ooooooooh,


EMI??


I still think we need a CTRL/ALT/DELETE for these d#$%ed things!
 

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Discussion Starter #5
Has know one else had this happen? I reconstructed the scene this morning just to make sure I wasn't crazy. Same thing happened. The noise of the vacum is causing the horn to activate.
HELP!!!
 

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EMI or RFI; (Electro Magnetic Interference- Radio Frequency Interference)
The brushes in your vacuum cleaner create sparks; these can create RFI. The motor winding can create EMI.
Probably no damage done..


Thanks for the tip, I think I will vacuum my truck with the long extension hose from now on.
 

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Discussion Starter #7
What the H-LL. Have I stepped into the Twilight Zone?
 

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Yep, I agree that it's probably not any *sound* noise but electrical noise that's setting it off, Bowhunter. Your vac is proably putting out enough energy to trip a circuit in the Body Control Module (BCM) and fire off the horn. Remember how the old Hoover "torpedo" vacs used to scramble the TV picture? Even the picture in the next apartment or room? Ooops! I'm showing my age!
 

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Any chance you were leaning on the horn pad while Vacumming?
 

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Discussion Starter #10
Max,


No, The second time it happened the vacum was sitting on the floor of the drivers side and I was standing outside the passenger side door.


Tom,


I see what you're saying. Is this something that can be isolated and grounded or do I just live with it and buy a longer vacum hose? And yes you are showing your age. This has me dumbfounded. I haven't done a search on this topic. Is there info on this out there?Edited by: Bowhunter
 

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Bowhunter said:
Is this something that can be isolated and grounded or do I just live with it and buy a longer vacum hose?

I'm guessing you'll just have to get a longer hose unless you want to disconnect your negative battery cables each time you vacuum. I'm thinking it's just a "fluke" that the RFI that your vacuum motor is producing is just frequency-matched to a piece of wire under the dash that acts like an antenna to trip the horn in the BCM. The vacuum brushes may wear and shift frequency - who knows? I'd try one of those coin-operated vacs down at the car wash. If you have the horn problem there, at least you won't disturb the family and the pets!



Does this sound like I'm old:


Out the window and up the fire escape: "Norton! Norton! Tell Trixie to turn off that vacuum - I'm trying to watch the fights down here!"
Edited by: Idle_Chatter
 

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Just be glad the horn goes off instead of the airbag.
 

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Discussion Starter #13
Tom,


As my grandfather use to tell me, "...not old just well seasoned."


Long live Jackie G.
 

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yep definately the vac emi setting off the horn section of the BCM. The Bcm is just below the steering column- just above where your vac was. Don't put it near your ecm or pcm!
 

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YOu could also unplug the horn relay. Best bet would be with a longer hose though!
 

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Discussion Starter #16
Army,


Pardon my ignorance but what does ecm and bcm stand for. Has any damage been done you think?
 

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Engine Control Module, Body Control Module.
 

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ECM is the Engine Control Module - The ECM constantly looks at the information from various sensors, and controls the systems that affect vehicle performance. The ECM performs the diagnostic function of the system. The ECM processes the various input information and sends the necessary electrical responses to control fuel delivery, timing and other emission control systems (such as the two FICM - Fuel Injection Control Modules)


BCM is the Body Control Module - The BCM controls/monitors the instruments, warning lights, audible warnings, all vehicle lighting and signaling circuits, entertainment systems, keyless entry and security systems.


AND, right here under diagnostic procedures for "Horns Always On" is:


1. Install a scan tool, 2. Turn ON the ignition, with the engine OFF, 3. With the scan tool, command the Body Control Module Horn Output ON and OFF.



And Camstyn is correct, the SIRS (Safety Inflatible Restraint System) is ALSO in the BCM!



We Actually have 5 computers on the DMax: ECM, BCM, two FICMs and the TCM (transmission control module).
 

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What's an FICM?
 

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srode said:
What's an FICM?

Fuel Injection Control Modules - flat silver boxes on both valve covers that say "do not spray with washer wand!" One for each bank of 4 cylinders and both cooled by fuel flow from the tank to the OEM filter.
 
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