Hi - horn not working.

I pulled the horn off and tested on a battery and the horn works. Checked fuse 15 - horn and wipes - fuse good and wipers working.

I cut back the wires a bit on the horn connectors under the car to make sure I had good clean wire contact to horn - but still the horn no work.

Thinking it might be steering wheel switch... or a break in the circuit. I can see the wires to the horn join in another loom of wires and seem to go straight into the firewall. Does not seem to be another connector along the way.

The wires under the car close to the horn are in fair shape but it is possible there is a break in the last section of wiring. I could cut that back a few feet into good wire.

There are two pairs of wires that run to the horn - where do they split from - they both seem to go all the way back. I tried each pair and neither pass current.

Does anyone have any thoughts or maybe suggests some predictable horn circuit failure I can look at?

Thank you,

Dean

I'm going to guess the steering wheel column slip ring, what some may call a clock spring, though which contact is made for the SRS Air Bag (if equipped) and the horn.

http://www.volvowiringdiagrams.com/?dir=volvo/740%20Wiring%20Diagrams

The 1993 Volvo 940 PDF page seven shows the circuit.

The slip ring can fail, losing all continuity with anything on teh steering wheel.

The slip ring, or clock spring, is the thing that allows you to turn your steering wheel while you have full horn tooting ability as you turn.

The Volvo 740 1989 Wiring.pdf on page six shows the same thing.

Else, maybe carbon pitting of the horn switch prevents continuity, thus, no electrons flow through, and no 1990 Volvo 740 toot-toot.

Does your steering wheel have the two horn buttons on the steering wheel spokes?



How you remove the horn switches is beyond me. Maybe prise up at along an edge or corner so you can test continuity.

Yes the steering wheel has the two buttons on the spokes for the horn.

Do I remove the air bag cover to look at the slip ring by disconnecting the negative battery terminal and loosen torx screws on the back of the steering wheel?

Is that the process to view the slip ring?

Thanks for you help.

Hi there,

Recently got my horn working by moving the air bag out of the way a bit. My problem ended up being how the wires come into contact with the slip ring.

Before going that far maybe see if the button(s) are in working order. There is a write up in the faq I believe.

But yeah thats how you get in there. I left the battery disconnected for 1/2 hour to be on the safe side before working near the air bag.

Hope this helps

https://www.brickboard.com/FAQ/700-900/ElectricalLightingHorns.htm#HornButtons

Yep, like Moustacio says, be careful around the air bag.

Does the air bag, when you press, also serve as the horn button.

If not, you need only be concerned with the two horn buttons on the steering wheel spokes.

Else, well, I dunno.

Hope that helps.

Fig and Kefir Midnight MacDufffed
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Thank you all for your help. I have tracked it down. I might have had multiple problems.

1. The two switches on the steering wheel spokes are worn and likely not making a good contact, and worked them a bit and they might need more help. The covers just pull off - makes it easy. The right switch seems to have more wires go to it - maybe if the right switch is out the entire circuit is broken.
2. I used some electrical cleaner on the disk contact on the steering column - and also worked and cleaned the spring contact that hits the disk.
3. One of my horns is broken - only one was working - and they we both badly corroded.
4. I blew a fuse #15 in the process.
5. Yep, I disconnected the battery terminal and avoided deploying the air bag.

So I went in all directions and have one working horn. Ordered another.

Thank you again.

Or other continuity failure. I've had the single wire that connects the power or load side to the horn ring on my 79 242 disconnect. Also, a wire could have flexed or chafed so that the copper inside has broken.

I am going to look at the horn ring - that is under the air bag cover?