So my horn.
 

Trouble shooting so far.

Horn button presses in makes relay in CPU click
Wires jumped from GW wire to GR wire no horn
Stop fuse verified good
Battery jumped to green red wire connection for horn - Have horn!

Wiring loom is a bitch to get to lol. During my search I found some people saying the relay is behind the front bar with the rest of them but the diagram says that the only relay is in the CPU which is clicking.

So pretty much with my logic somewhere between the fusebox and my horn there is a broken wire? Or is there something else I'm missing

So got a long bit of wire and connected it to the GR wire that connects it to the horn and ran it back near the CPU so I could check continuity between it and the GR wire coming off the CPU plug and it has continuity. The GW wire measures 12v with a multi meter and when jumpered to the GR wire I get no horn. However when I jump the wire from the battery to the horn it works. The CPU also clicks. So it seems to me like nothing is wrong but I'm still getting no F'n Horn

their is an odd chance that the CPU relay may still be bad. check the wire coming from the ECU to the horn with a test light.

electrical current always has a begging and an end. follow the path from the battery to the horn.

my test light has a sharp end so you can push it through the insulation into the wires. so you don't only have to check at a connector. just mind your fingers, theirs no wires in them.

Yeah, my relay stopped clicking when I plugged it back end so now I'm thinking its the solders, pulled the cpu out and they look pretty shitty. Going to do a resolder. Still doesn't explain why jumping wire that has 12v to it to a horn that works when 12v is applied gave me nothing. Going to resolder, if it starts clicking just going to splice in another 12v wire to the CPU

CPU solders looks shithouse, but so is my soldering. Guess my car will have to wait a day, ill get one of the avionics guys to fix it tomorrow

You measure batt voltage on the GW and then connect it to the G/R and no horn.

But if you run a piece of wire from the batt to the G/R the horn honks.

Meaning to me that the GW wire can't carry a load. It may read batt voltage when measured all by itself............but if I were you I'd jumper it to the R/B and at the same time have your meter on the GW to watch what the voltage is. I suspect the voltage drops to zippity when the horn button is pushed.............proving the GW wire connection either at the fuse box or ??? is barely making contact with fuse.

Kinda a not unusual event. I've seen systems on airplanes that don't work. Power is there when looked at with a meter but the voltage drops off when a load is put on the system. Usually a crummy waffer solder joint.....waffer plug half ass on its mate........sometimes but rarely a CB that isn't up to snuff. Half ass connections don't cut the mustard.

But in your case I fail to see how it would be a CPU solder joint 'cause you jumpered the G/W directly to the R/B and nothing came of it. CPU was out of the picture when you did that. But the horn honked when a seperate wire was run from the batt to the R/B proving the problem lies in the G/W wire and or connection at the interior fuse box or ???? There's no other connectors b/t the fuse box and the CPU for it other than what seems to be a internal to the harness splice which you'll NEVER find unless you cut the harness apart (and that ain't a gonna happen 'cause it'd be dumb to do so).

I assumed it was series four car.

Half ass crimps of the terminal of the G/W at the CPU harness plug or at the termination at the fuse box could also cause a poor connection.

Never let a Avionics PUKE work on anything ever. Give 'em a crossword puzzle to read and send 'em to the back of the hanger to work on that. Keep 'em off the airplane (humor)

In all of this do your brake/stop lights work properly? Have you tried to unplug the largest connector at the CPU which houses the relevant wires and jumper voltage from another source to the G/R wire to see if it will sound off? The G/W wire is multistranded and if only one strand were still intact there would be continuity but not necessarily enough meat to pass the necessary amperage through the wire as required.

Sorry, I wrote R/B when I should have written G/R in the other reply. My very bad mistake in typing. Had headlights on my mind when writing R/B.

He already put the G/W to the G/R and it did not work. When he put the wire from the battery to the G/R the horn honked. Fuse is good 'cause the horn relay in the CPU pulled in when the horn button was pushed. Well, almost proves the stop fuse is good.

My mistake. I wrote R/B instead of G/R. He already jumpered the G/W to the G/R and the horn didn't work. Horn worked when G/R was jumpered to the battery positive post.

Horn relay pulled in proving to some extent that the Stop fuse is good.

Not a big deal, but when he said he took voltage from the battery to the horn and it sounded I wasn't sure if the voltage was directed to the CPU plug or the horn(s) itself.

For some reason jumping those 2 wires didn't make the horn go off yesterday.

But anyway one of the avionics guys soldered up the CPU for me today as my soldering skills are pretty poor, I'm just a dumb sheety haha and now the horn works. No fucking idea how after joining up those 2 wires should have bypassed the relay but it works, so I don't give a damn. Now I can register the car tomorrow =D Thanks for your help guys