Help - Horn sounding problem

[Hawk]

About a month ago, the steering shaft lower joint was tightened on my TR6 to remove a bit of play.  After that I drove it for around 300 miles with zero issues and then, on one of the hot days in July, the horn sounded as I was parking.  I thought that maybe the horn assembly had expanded in the direct sunlight and that this was the cause and thought nothing of it. 

The a couple of days later, when climbing out, the horn sounded as I lent on the steering wheel.  And I managed to replicate this by pulling on the steering wheel .... and left it for the weekend.

Mrs Hawk then took out the TR and phoned me from the side of the road to say that the horn kept going off ... so I talked her through pulling the wire from the relay and she drove home. 

Assuming that this problem was caused by the steering shaft being moved, I decided to move the inner steering tube by loosening the clamp in the engine bay as I had read this was a potential cause.  But that has seemingly made matters worse and now the horn is sounding constantly.  

Any ideas?  Nothing else has been tinkered with so it must be related to the steering column?  

 

 

[RogerH]

Hi Peter,

have a look at the gap between the steering wheel hub and the steering column cowl. It may be touching.

Undo the top slidey thing and open the gap.

 

Roger

[Mk2 Chopper]

To sound the horn you are earthing the supply through the steering inner column. 

So somewhere it's getting its earth without the horn button being pushed. 

You've managed to make it worse, so I would look to see the angle of the inner column isn't touching the outer one, and as Roger suggested check the wheel position and its clearance, and what moves as you push and pull on the steering wheel.

Edit:

Thinking about it, the inner column is always earthed, it's the horn push that isolates it. There is 12v to contact ring under the steering wheel, and a brush with spring connects that to the horn push, so your best bet is to take the wheel off and investigate there. 

Gareth

Edited August 11, 2021 by Mk2 Chopper
Correction

[harlequin]

3 or 4 people in the local group have similar horn issues, the common denominator is they all have aftermarket steering wheels and hubs. If yours is also an aftermarket item have a look at the spring pencil thingy as it may be shorting on the hub.

George 

[Kevo_6]

I had the same problem, normally going around a tight bend. I sorted mine with new uprated column bushes and correctly aligning  the column to my Motolita  steering wheel as Roger has suggested.

[Hawk]

Thanks for all of the help and guidance.

The steering wheel is Mota Lita and so I will investigate but it has been on the car for 5 years plus with no issues which is why I was looking at the steering column.  Will remove wheel and take a look. 

[Hawk]

Quick update.  Removed horn push and horn still sounds when relay is connected.

Roger - there is a gap and I widened it but made no difference.  

[Mike C]

I have a Moto Lita steering wheel and it was intermittently shorting out through the boss in the centre of the hub- from memory there was a batch of ML made with incorrect centre hubs about 30 years ago. I had to file the hub down to get clearance.

[Mk2 Chopper]

Can you take out the brush and see if that makes a difference?

[Hawk]

42 minutes ago, Mk2 Chopper said:

Can you take out the brush and see if that makes a difference?

No difference.  

 

[ntc]

7 minutes ago, Hawk said:

No difference.  

 

Then you will have a trapped earth under the cover under the column 

[Mk2 Chopper]

29 minutes ago, Hawk said:

No difference.  

 

Take the wheel/boss off because something is going to earth and that's where the 12v comes onto the steering column area under the boss. Hopefully you'll see what the cause is under there. 

[Hawk]

Steering wheel off and no difference - horn still sounding when relay connected.  

 

And I can't see any trapped / stripped wires?  Anything in particular I should be looking for - I'm an idiot when it comes to electrickery. 

[Ransomes256]

Have you checked the relay?  Has it frozen closed?

Disconnect the horn feed so you don't go deaf then check if you can hear / feel the relay click on and off when making the switch connection.

Neil

 

[Mk2 Chopper]

You sure the relay is connected up right? The next thing is to find the supply wire and where it comes into the column under a removable plate as if this wire shorts the horn will sound. 

[Hawk]

4 minutes ago, Ransomes256 said:

Have you checked the relay?  Has it frozen closed?

Disconnect the horn feed so you don't go deaf then check if you can hear / feel the relay click on and off when making the switch connection.

Neil

 

Yes, relay clicking so I'm assuming it is good.  

[Hawk]

4 minutes ago, Mk2 Chopper said:

You sure the relay is connected up right? The next thing is to find the supply wire and where it comes into the column under a removable plate as if this wire shorts the horn will sound. 

 

It is definitely connected as it was before and has been for the last 5 years - I take reference pictures of everything before I take apart.

 

I do have another relay so will check that as well. 

[Mk2 Chopper]

24 minutes ago, Hawk said:

 

It is definitely connected as it was before and has been for the last 5 years - I take reference pictures of everything before I take apart.

 

I do have another relay so will check that as well. 

Good idea just to be sure. Still sounds like the 12v power to the column is shorting out, so maybe try disconnecting the power to the horn ring, if it still makes the horn sound, then that wire is touching metal some where along its route. 

[ntc]

Have you removed the cables cover under the column?

[Hawk]

6 minutes ago, ntc said:

Have you removed the cables cover under the column?

Yes I have ... and I can't see anything obvious. 

[Hawk]

18 minutes ago, Mk2 Chopper said:

Good idea just to be sure. Still sounds like the 12v power to the column is shorting out, so maybe try disconnecting the power to the horn ring, if it still makes the horn sound, then that wire is touching metal some where along its route. 

OK - so same issue with spare relay so safe to assume that is ok.  

I believe I am looking for a purple wire to disconnect?  Is that right?  And do you happen to know where the connector is?  I presuming under the cover under the wheel? 

[Mk2 Chopper]

I'd be guessing without a wiring diagram in front of me, but the wire connects to the horn ring beneath, how easy that is to remove I'm not sure? I believe if you remove the switch cowl you'll see better inside that area. 

Gareth

[stuart]

Theres a slip ring under the wheel in the top of the column with a purple wire connected to it, if that wire has come adrift from the slip ring then it is probably touching the side of the column tube hence sounding the horn. It connects under the dash to the cluster of wires from the lights switch/indicator switch and overdrive switch if fitted. Should be a lucar joiner to a Purple/black

Stuart.

[Mike C]

9 hours ago, Mike C said:

I have a Moto Lita steering wheel and it was intermittently shorting out through the boss in the centre of the hub- from memory there was a batch of ML made with incorrect centre hubs about 30 years ago. I had to file the hub down to get clearance.

I'm in lockdown so I can't look at my car- from memory the centre boss was shorting out to the brass  earthing  ring when the steering wheel was loaded during turns or sometimes while holding on over bumps. The aluminum centre  boss came too  far down the shaft.

[GeoffreyS]

I experienced the same.  Gosh it is embarrassing.  I have a MotoLita steering wheel.  If stated to develop a little bit of forward/backward play.  Only about 1/16th”.   Enough to upset the earth.   To stop the horn sounding, until I could have it remedied, I had to pull the steering wheel toward me while driving.  (Removing the horn fuse gave for an easier, although not legal, drive).