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Discussion Starter #1
Well, I've not been able to get to the bottom of this issue yet and hoping someone can help. When I bought my 900 the horn fuse was removed. Upon installing the horn fuse I discovered the horn is stuck on if the car is on (key in the on position).

I have disconnected the horn switch, and it is still stuck on. I have verified with a multimeter power is going to the horn relay, even with the horn switch/button disconnected. So my short must be somewhere between the horn button wiring and the relay. Anyone have any clues as to where it could be shorting? Or have a wiring diagram for the horn? Specifically the steering column to horn relay, and how to access?
 

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Here's the schematic for the horn circuit out of the 16V bentley manual.





pic page



The horn relay switched contacts are fed direct from the terminal 30 circuit (permanently on with battery connected). The ignition lock relay controls power fed to the horn relay's coil contacts (so with ignition off the horn is 'isolated').

Check what's going on there first, then you need to trace from the 'negative' coil contact of the horn relay (pin 85) as that runs up to the horn contact ring in the steering wheel.

Somehow it's getting shorted to ground. If you've disconnected the horn switch in the steering wheel then it's between the slip-ring contact and the horn relay itself.

Have you tried swapping the horn relay for one of the other identical 4-pin types to verify the relay itself isn't faulty?

If the problem still occurs, you'll need to lift up the fuse-relay panel and have a look at the wiring to the relay socket. Maybe the wire for the ground side (which feeds the horn contact ring in the steering wheel) is broken off and touching on the car metalwork, or one of the ground terminal strips under the fuse-relay panel. If that's all ok, trace that wire out to the steering wheel and it'll probably be shorting somewhere.

Craig.
 

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I had that happen on my 1984(first Saab)GL but it would just suddenly come on, and go off, but usually when you didn't want it to come on :cheesy::lol:;oops:, but one day it just didn't stop so removed relay. got another was ok sp presummed for whatever reason the relay was sticking/faulty
 

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Discussion Starter #4
I've verified its not the relay. Narrowed down the issue to the grounded leg, somewhere between the fuse box and the slip ring.

This weekend I pulled the steering wheel back off and discovered that the wire that attaches to the slip ring is actually missing. Looked all around the steering column area that I could access with the steering wheel and wiper stalk assembly removed. No wire to be found.

Does anyone know what color of wire I should be looking for? And where it was originally ran up the steering column?

Also, any tips on accessing the wiring at the base of the steering column? Am I going to have to remove the whole dash / knee bolster?
 

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According to the Bentley Diagram above it's a black wire.

I would expect the wire to be gouped with the blinker/wiper actuators wiring loom, so removing the bottom cover of the steering column cover should help you see better. Look for any loose black wires behind/underneath the panel.
 

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Discussion Starter #6
According to the Bentley Diagram above it's a black wire.

I would expect the wire to be gouped with the blinker/wiper actuators wiring loom, so removing the bottom cover of the steering column cover should help you see better. Look for any loose black wires behind/underneath the panel.
I had the lower column cover off, and the stalk assembly down. I just replaced the turn signal switch. I dug around in the wiring and foam, but couldn't find any single or loose wires. Everything looked in place. But the slip ring wire is not there. Thanks for the tip on the color!

I think I need to get the knee bolster out of the way. Or at the very least the black vent tubing near the foot well out of the way so I can look further down the steering column assembly.
 

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I am fairly sure you will not find a single wire close to the firewall where the steering column passes through it. The black wire comes from the plugs in the bottom of the fuse box and so are part of a larger loom. Removing the bolster will give you access to these - the area behing the ashtray and the heating control buttons is where you should look.

I don't remember if you can remove the bolster withour removing the black vent tubes thingie which is a total pain to reinstall. If you can, leave the black thingie alone!!
 

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Discussion Starter #8
I am fairly sure you will not find a single wire close to the firewall where the steering column passes through it. The black wire comes from the plugs in the bottom of the fuse box and so are part of a larger loom. Removing the bolster will give you access to these - the area behing the ashtray and the heating control buttons is where you should look.

I don't remember if you can remove the bolster withour removing the black vent tubes thingie which is a total pain to reinstall. If you can, leave the black thingie alone!!
Many thanks. The tips for locating the lost wire were quite helpful. Horn now working again. Beep Beep!

I removed the dash insert around the gauges and heater controls to find the horn wire. Which was a single black wire with a piece of numbered red plastic zip tied to it. The PO had the wire connected to the dimmer switch for the dash lights and left the correct ground wire disconnected. There were actually a few other things I found out of place and corrected as well, so my heat controls work now as well. I am learning a clumsy previous owner can cause more harm than good when trying to "fix" things.
 
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