A different to the last post intermittent horn

[kit]

I have a different intermittent problem that the horn will sound once and then no power is registering at the steering wheel or one side of the horn, there is power going in and sometimes on both sides but often only one, I have ordered a new horn from a reliable source the current one came from JK so hopefully that will solve the problem unless I have overlooked something?

[Jeff J]

The horn button puts or should put an earth (-ve) onto the horn when pressed. Have you checked the switch for continuity each time you press it?

[Oldiebut goodie]

Loose earth on the steering column? Have you checked it?

[Slider2]

Just fixed my horn today.
Spent hours yesterday checking continuity etc having similar symptoms to yours.
Main feed (black & yellow at horn) was showing 12v
And the button was switching ok.
Slip ring was making a reasonable connection
Jump wire on shaft was oxidised but ok.
Resistance in the system was in the order of single figure ohms....but just gave a single parp before switching to a whispery click at the horn.

I wanted to upgrade it anyway so today used the std wiring to energise a relay and provide switched earth to a pair of vw/audi twin horns.

Ran a new 15a fused supply from the battery.

The existing circuit seems reliable in switching the relay and all works well.
I'm still a bit gutted I couldn't find an absolute reason why the existing circuit couldn't sustain the horn beyond a short parp once in a blue moon. Odd.

Must have been a poor connection somewhere between fusebox and horn or perhaps somewhere in that enormous cable run from steering box to horn on the earth side.

(Come to think of it, I ought to power my relay 12v from the new feed rather than rely on the supply from the fusebox if it is still in doubt)

[syncroandy]

The base-spec T3 horn circuit does seem a bit prone to problems.

The horn needs a good strong current to operate properly. However, due to the design, with semi-exposed push-on connections to the horn, which is in a location exposed to road spray etc, that single blade connection on the steering column, and the slip ring wich can wear out and tarnish, resistance can build up causing the horn not to operate fully or at all. Folk often fit cheap aftermarket replacements too, which aren't as good as the real deal.

What I've done on both my vans, is upgrade to the dual-tone horn setup which AFIAK was only fitted to the Carat. This requires a relay to be fitted to the relay plate (or on top in a clip-on base), and a bit of re-wiring. I use the twin-tone horns from scrapyard Mk4 Golfs or Passats. The relay switches the heavy current to the horn, the slip ring only has to provide the much smaller relay trigger current.

The only fly in the ointment is that to use the Carat setup with the relay on the plate, a specific connector is needed, the grey 4-pin 'L' plug at the far right of the plate. These plugs are NLA from VW, and the only source is therefore to rob one off old CE1 dash harnesses from Mk1 Golfs etc. For most folk therefore, a more feasible approch is to use a separate relay clipped to the top of the plate.

Wiring diagram for the Carat setup:



E D I T: Just re-read all of your post 'slider2' I see you got there, great !

[kit]

New horn from Brickwerks works a treat, put a continuity test on the old one and it appeared to be dead tried it latter it was ok and again latter dead again, must have been an intermittent fault, thanks for the advice I think rewiring and a relay are in order.

[bigbadbob76]

Thanks for the details Andy.
My horn gives a good strong "Beeeeeeep..." when the engine is running but only gets as far as "Bp" when not running.
Relay and heftier wiring will hopefully cure it.

[syncroandy]

No probs. If re-wiring, and fitting dual horns and a relay, I recommend putting in a separate 1.5mm wire for each horn.

I've found that if wired on a single wire, and fanning out right at the horns, one of them can sound first and drag the voltage down (due to the resistance in the wire) just enough to prevent the other from sounding.