Need a hot wire
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Freshman User
Joined: Aug 2005
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Need a hot wire
I am getting ready to hook up my air horn this weekend on my '06 F250 PSD and would like to hook the button to a 12v wire that is hot all the time. (when the truck is on or off)
If my logic is right, having the hot wire going to the button would not draw down my battery at all becuase the power would only be used when the button is pushed. Correct?
I have my air compressor already hooked up and running great, it is powered directly from the battery and uses one of my upfitters switches to power it on and off.
So is there a customer supplied lead that I could use under the dash to activate my horn.
If any of my logic is wrong please let know or if there is a good reason not to have the button hot all the time please let me know.
Thanks,
Rufus0415
If my logic is right, having the hot wire going to the button would not draw down my battery at all becuase the power would only be used when the button is pushed. Correct?
I have my air compressor already hooked up and running great, it is powered directly from the battery and uses one of my upfitters switches to power it on and off.
So is there a customer supplied lead that I could use under the dash to activate my horn.
If any of my logic is wrong please let know or if there is a good reason not to have the button hot all the time please let me know.
Thanks,
Rufus0415
Postmaster
Joined: Mar 2001
Posts: 4,968
Likes: 3
From: So Cal
I don't know specifics but there are several hot lines in the fuse box. Use a meter to find which ones. Make sure that the fusing and wiring is adequate.
An alternate, at least on my 94 is, there is a hot line on the starter solenoid and it has a pretty decent current capacity.
The GOTCHA to an always live line is that if anything happens you could be drawing a lot of current for some time and could cause a fire. I almost had this happen with my truck. The camper shell company who wired my shell for power pulled the power off the starter solenoid as mentioned. They did not fuse the line and it was not well protected where it went thru sheetmetal.
I was out on an all week campout and when I got back, my truck battery was dead, the camper light was melted, the wiring was melted etc. The only way I found the problem was that when I popped the hood there was smoke still coming off the smoldering wires. I think the wire to the shell had chaffed over time and that the constant draw from the light made the wire heat a little which let the insulation get soft which then caused a short
So be sure you have fusing and that you protect the wire anywhere it might rub against something.
Good Luck,
Jim Henderson
An alternate, at least on my 94 is, there is a hot line on the starter solenoid and it has a pretty decent current capacity.
The GOTCHA to an always live line is that if anything happens you could be drawing a lot of current for some time and could cause a fire. I almost had this happen with my truck. The camper shell company who wired my shell for power pulled the power off the starter solenoid as mentioned. They did not fuse the line and it was not well protected where it went thru sheetmetal.
I was out on an all week campout and when I got back, my truck battery was dead, the camper light was melted, the wiring was melted etc. The only way I found the problem was that when I popped the hood there was smoke still coming off the smoldering wires. I think the wire to the shell had chaffed over time and that the constant draw from the light made the wire heat a little which let the insulation get soft which then caused a short
So be sure you have fusing and that you protect the wire anywhere it might rub against something.
Good Luck,
Jim Henderson
Cargo Master
Joined: Jan 2002
Posts: 2,079
Likes: 11
From: LA and CO
Not sure if it's there on your truck, but 02 was the first year they moved all fuses inside the dash. On my dad's 02 there happens to be a nice hot wire terminated right on top of the driver's fender where the fuse/relay panel was before it was moved inside.
If not get it from the solenoid, but use a fuse or circuit breaker, or better yet a relay....
If not get it from the solenoid, but use a fuse or circuit breaker, or better yet a relay....
Posting Guru
Joined: Jul 2006
Posts: 1,191
Likes: 0
From: New York
When I wired my airhorn, I used one of the 4 pass through wires for the switch and wired it right to one of the battery wires coming off of the battery. No real power draw because it is only activating the solenoid switch to open to let the air flow through. I have a relay that gets juice from the customer access white/blue wire so it can only power the air compressor with the engine running. The power feeds for the air compressor themselves come from a fused large gauge wire direct from the battery. With this setup, I wired a switch so that my Viper alarm when tripped will not only sound the siren, but also can trigger the solenoid and blast the air horn simultaneously. It will automatically drain out the air in about 30 seconds, and won't automatically kick back on, so it is a nice surprise when the alarm trips, but I won' t drain my battery. I can just switch that feature on or off.
