second air horn in fj

howie ll wrote: Soundandsecurity, nice points but there are 20 ways from here to Sunday to do this. But air horns AND compressor with wiring? Also every compressor I've ever seen was polarised, why you want it to blow not suck. Lastly, by ISO convention, 85 is the coil NEG, you'll run into trouble using 86 as the NEG if you ever come across a relay with built in diode.

yea i seem to have insulted his ego cuz i compared his FJ cruiser to a Hummer so i figured id make it up to him by writing it up step by step. plus it's not an air horn without a compressor and i can already predict the inevitable response saying "ok i did that, now how do i do this?". i know, theres always more than one way to skin a cat. yes howie, every compressor ive come across was polarized, but the actual solenoid on the horn itself usually isnt. also good point about the relay being polarized, i can never remember which terminal is supposed to be positive and negative, most of what i deal with isnt polarized. sadly its not worth be buying expensive relays with the diode across the terminals so its rare that i have to factor in that detail. ive installed more than a few train horns since they started to get popular on cars and trucks and everybody always wants it hooked up some special way so naturally you get good at adapting the wiring to make it work how they want it to work.

Yes, nothing wrong with your points, I misread your earlier post, lumping the solenoids and compressor together. The convention puts 85 (-) NEG coil, 86 (+) POS side of coil.

Guys, thanks a lot, this is great!!! Last night I thought of something similar to what soundnsecurity described. It's funny because I've always used 4 pins of the relay, and only last night realized that 87a is there for a purpose. But before that I had those "OMG OMG I'm so dumb need forum people to tell me how to hook it all up" moments I suppose the best way to do it would be assembling a system on the table with 12V LEDs instead of horns to see how things work. That will help me visualize the whole thing much better. soundnsecurity no insults, I was just joking, in fact I'm used to it, when people go, so this is like a small hummer? but thanks a lot for the write up...something to do this weekend Once again, thanks a lot, I'll play with it on a table first before going to the car which will take a while anyways.

no problems man, no insults taken, i have just as much as sense of humor as you do. i feel bad having to compare anything to a Hummer but sometimes its just the easiest thing to do to get the point across. if you come up against anything that doesnt make sense with my diagram just let me know and ill help you out. not all air horns are exactly the same so im just going off of what is most common. if anything is different just let me know and ill help you work it out.

At least the Hummer has a decent engine. (Isuzu.) Ooops...

Really Peter?

Yeah - apparently crapped all over the smaller original engine... (Makes me think Hummer is GM - our GMH seem keen on undersized engines!)

I believe General Dynamics built the original military version, GM made the civilian version. Under engined? You obviously don't mean the lovely Holden/Vauxhall Monaro M5 Series eater?

I'm thinking more of the Isuzu D-Max and its "local" (GMH) Holden Colorado. I think the Colorado is one of those 100,000km engines. I was told the other day it's a mere 2.2L. PS - maybe the Monaro has one of the GMH "export" engines. They are apparently quite good.