Just wanted to revisit my problem-I need to tap into a 12 volt source with enought amps for my airhorns (20 amp fuse recommended). I would like to avoid running a line from the battery in the trunk. Already tried the P/S and jumpstart terminals-not enough amps. Would one of the empty slots in the fuse box be ok to tap into? I could just put a female spade on the wire and plug it in to connect the relay.

If anyone has a wiring diagram of the fuse box, it would help. I feel silly having these cool airhorns, compressor, etc in the car without being able to use them.

Constant 12v or a switched source?

Either one would do. It is for the auxilary air horns.

http://www.directechs.com/timages/12v_6041.jpg

You can grab a constant 12v at BCM C3 in that image...12v is red/black

Thanks for the info. I didnt even realize there was a fuse box in there. But I would prefer the box in the engine compartment, since that is where the relay is. It would save me running more wires through the firewall grommet.

I wouldnt pick up power at the BCM, in fact I wouldn't mess with the BCM at all. It has to be one of the most complicated and touchy modules in the car. It controls just about everything and they like to fail quite frequently. We've been slow lately, if I have time tomorrow I have a couple of things to do to the car anyway, I'll pull a schematic and poke around under the hood. I'll find you some place to pick up power.

Thanks, Aaron. I would really appreciate it.

New cars are so much trickier to work on than old ones.

I wouldnt pick up power at the BCM, in fact I wouldn't mess with the BCM at all. It has to be one of the most complicated and touchy modules in the car. It controls just about everything and they like to fail quite frequently. We've been slow lately, if I have time tomorrow I have a couple of things to do to the car anyway, I'll pull a schematic and poke around under the hood. I'll find you some place to pick up power.

I've gone to the BCM plenty of times to do remote starts in the newer Chevy's (that's your best place for power in the new ones), and I've yet to come across any issues whatsoever.

I've gone to the BCM plenty of times to do remote starts in the newer Chevy's (that's your best place for power in the new ones), and I've yet to come across any issues whatsoever.

Let me guess you work at a stereo shop.

Let me guess you work at a stereo shop.

:)

Look at the new GM's- just about all of them lack a constant and a starter wire at the ignition harness, leaving you the BCM :)

Everybodys an expert on the internet :roll: , do whatever you wanna do. Lee I'll find you a place to pick up 12v under the hood. I replace BCM's quite frequently, more so than any other module in a vehicle. So I personally wouldn't start probing wires coming out of the BCM, but what do I know.

Everybodys an expert on the internet :roll: , do whatever you wanna do. Lee I'll find you a place to pick up 12v under the hood. I replace BCM's quite frequently, more so than any other module in a vehicle. So I personally wouldn't start probing wires coming out of the BCM, but what do I know.

Never said I was an expert at anything :confused:

Don't know what the attitude is for...all I know is that I've tapped into the 12v in the BCM on a ton of newer GM's and I've yet to have a problem...but what do I know.

...but what do I know.

How to "play nice" on a web forum and that counts for something! :thumb:

"It's a cruel, cruel place...ChevyHHR.net" (our new slogan?) :confused:

How to "play nice" on a web forum and that counts for something! :thumb:

"It's a cruel, cruel place...ChevyHHR.net" (our new slogan?) :confused:

lol

snksknr94- didn't mean to come off as being an ass or anything...just giving my personal experience on the subject.

**** it, I'm done trying to help people on this site.

Lee there is a post terminal at the fuse block that has power coming to it directly from the battery, yuo should be able to pick up 12 v there, I'll varify after lunch. This maybe the one you already tried though. I'll try and put a load on it and see if it goes dead.

I tried both of the terminals outside of the fusebox. I even tried connecting the compressor directly to the post for jumping the car, but it only gave a weak sound. I believe this indicates not enough current. I don't understand why it wouldnt work.

My first attempt at hooking up the airhorns was to use the post for the powersteering. It worked for a while (in the driveway), then suddenly stopped (while I was driving). Perhaps the additional strain of the horn and P/S was too much for the circuit? But after that, I could not detect any power in any of the connections at the fuse box (but mysteriously everything still worked). Just as strangely, one day I checked and the power was back. My siren began working again. It is all too wierd. :confused:

You should be able to pick up 12 volts at the front post to the left of the fuse block, the one under the red cover. I did notice that the post seems to be coated, I had to scratch my test lamp around a bit before it would light. Maybe take some steel wool or fine grain sand paper and rough up that post, and try it again.

Thanks. I'll give it a shot later, and let you know what happens.

I tried tapping into the terminal for boosting the car with the same result-nothing. It gets 12 volts as shown by test light, but will not drive the compressor. When I tried both the test light and the compressor at the same time, the light went off when the compressor was connected, indicating serious draw. Note that the compressor was hooked up directly (with fuse) but bypassing relay and switch, eliminating any variables.

What gives-what is wrong with this connector? I did this at my friends auto stereo/alarm/custom installation shop with a very experienced tech. He suggested running a test line direct from the battery, first ground then power to see which connection is not adequate, although we are both reasonably sure it is the positive end. But if the boost terminal on the HHR were actually connected directly to the battery, then it would work. So something is in there blocking the power.

When I tried both the test light and the compressor at the same time, the light went off when the compressor was connected, indicating serious draw.

What gives-what is wrong with this connector...something is in there blocking the power.

You are correct! There is a circuit breaker there. When it detects serious draw, it disconnects to prevent excessive battery drain. I'm not sure where you are going to pick up a 20A circuit from the underhood fusebox without encountering this problem.

You can tap from the center console fusebox - off the main red wire entering the BCM, but this would necessitate running a "hot" wire through the firewall grommet (near steering column), to get it underhood. I'd only do that as a last resort, as having a hot wire ground on the firewall could cause a nasty short!

How about the stock horn wiring? Does it go through a relay? Maybe I could just connect the stock horn, that uses less current, to my extra switch and run the airhorns from the steering wheel horn button.

How about the stock horn wiring? Does it go through a relay? Maybe I could just connect the stock horn, that uses less current, to my extra switch and run the airhorns from the steering wheel horn button.

Here is the schematic for the horn.

http://n8zcc.com/pics/HHR/HornSchematic.gif

Thanks Monster. So with 10 amps, I guess I cant run the compressor off the stock wiriing. So I am back to the drawing board. It seems crazy to have to run a high amp line from the interior fuse box or from the battery, though. :eek:

Well, I remember seeing a 50 amp feed feeding the underhood fuse box. Why can't you take your tap there?

The underhood fuse box feeds power to the interior fuse box/BCM by a 40 amp feed, so it would not make sense to tap there for the power.

That would be great-where is it? Also, the headlights draw a lot of current-what feeds them?

That would be great-where is it? Also, the headlights draw a lot of current-what feeds them?

The under hood fuse box feeds the head lamps by a 10 amp circuit.

Look around the under hood fuse box, a 50 amp cable is going to be sizeable so you should be able to see it. I don't have any pictures of it's location, sorry.

I see that there are several fuses in the engine compartment fuse box of 30 amps. So the box itself can handle it. What about using a spade terminal to one of the empty fuse slots??? :confused:

Unfortunately my schematics don’t show if or how the empty spaces are wired, sorry.

I am guessing that they must come from a main wire that can carry the maximum load of any fuse in the box. So, in theory I should be able to tap into any of the unused plugs. I am just a little apprehensive due to my previous problem after using the powersteering post (I lost power there for about a week, then it mysteriously appeared again). :confused:

I am getting ready to give up on these stupid airhorns. I took the car to the Chevy dealer for the antennal to be ordered, then asked him about a good power source. He suggested one of the empty fuse slots, like I suspected. But when I tried, it did not work either. Apparantly although there are 40 and 30 amp fuses in the box, they dont draw anywhere near the max.

I am going to see if I can find a low-draw compressor or I will abandon the air horn idea and just get some louder electric horn(s).

Besides being electrically more efficient, loud electric horns will fit the look of your HHR better also. I would hit up a junkyard for an older buick or cadillac horn - those puppies were LOUD!

You make it sound like I need an 'Ah-Oo-Gah' horn. :)

I figured on the Hi/Low like Fiamm (small and nicely painted).

Since I plan on building a project car I can still put these air horns to good use in the future (hopefully soon).

Now I am getting ready to give up (not really). I bought a pair of high/low horns. The wiring shows a 10 amp fuse, so I tried hooking one up directly to the fuse box, and still no sound. I did it quickly, and will try again. But something is definitely not right.

Sorry for bringing up old posts but I hid my air horn in my wheel well by my stock horn and used the stock lead to power a relay that runs my horns. Hit the horn button and they both go off!

I'm planning to add 70's Caddy 3 horns set-up to mine.