Horn temperamental. Steering rack / cross member ground location?

[james944]

Hello, I drive a 1984 2.5 LUX (early, square dash model) with yet another electrical gremlin!

My MOT is due in two weeks and for some rather irritating reason my horn is playing up. I thought I had it fixed when I realised one of the connections to the horn itself had rusted away. I replaced it only to find the horn was louder, when it chooses to work and not completely fixed! I guess the increased volume is due to only one of the two horns previously working.

So my issue is, I have a horn that only works when the steering wheel is at certain points during rotation.

I have checked the ground by the front light and the grounds in the footwell. All of which are good. The horn and the relay are functional. The relay clicks when the horn is activated (when it wants to work) and the horn sounds better than ever with the new electrical connection fitted (again, when it wants to).

I've had the steering wheel off, cleaned all three of the connectors in the horn pad, checked the wiring, cleaned the slider plate and re-greased it with electrical grease. The electrical connections to the indicator and wiper sticks are all good.

I have heard about a ground from the steering rack to the front axel cross member, this link is what I saw.

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/800411-horn-ground-off-steering-rack.html

I've searched high and low and cannot see it. Could this be why the horn only goes off wen the steering wheel are steering rack are in certain positions, could the ground wire be loose and I'm not seeing it?

I'm certain it's not a problem with the tab that connects to the slider plate as contact is flush through full rotation.

If anyone knows of this problem advice would be very much appreciated. I have searched for a ground wire from the steering rack to the cross member. I can't see it, I can't find anything online good enough to find it or to work out where to fit one myself. Has anyone seen any pictures of detailed description of where this ground is?

Does it even exist on my car....

Thanks
James

 

[colin944]

There is no ground on my S2 to the crossmember/rack. The rack is hydraulic and I can't see why you would need a ground on it. I would recon your problem lies at the wheel end of the setup. Do you have an aftermarket steering wheel? Have you made sure that the contact ring is in contact with the wheel all the time. Have you dismantled the horn push to make sure there are no loose connections in there ?

 

[james944]

Hi Colin,

Thanks for your reply. I didn't know for sure if there was a ground or not. I had been doing a lot if research on the problem and found a few links (like the one I posted, did you have a look?). I sure don't mind looking silly either as this is all a learning curve for me and I'm where people like to help each other out.

I did think the same about why you may need the ground on it as the horn is grounded to the body by the headlight but I don't know enough about electronics.

If you think the problem lays with the wheel then I will go and take it off again and check that slider tab. It is slightly worn, showing a bit of a dimple in it. Are they able to replace?

I don't believe I have an after market wheel, I have another 1984 944 which I tested the horn plate with and it works fine. I may take the wheel off that too and swap them over.

Thanks
James

 

[bmnelsc]

I agree with Colin here. As you've tested your horn ring and it works then that leaves only two options - the horn pad on the wheel is not depressing the horn ring enough to contact or you've got a frayed wire going down the steering column. On my S2 (with 4 spoke wheel and regular horn pad - no airbag) I had a broken plastic mount that held the pad on - nearly impossible to get the horn to work especially when being crowded off the road by old women in their new 540is. I replaced the plastic mounts and all was good. The horn ring actually works by completing the horn circuit so if the wire that plugs into the horn ring is frayed or broken somewhere down the column then you get no horn or possibly horn if a few wires are touching.

 

[james944]

Success!!

It turns out my steering column was grounded, no problem there. The slider plate and contact were fine. The horn pad had no faults or the wheel itself.

The problem was with the u-joints in the steering column. After applying electrical connection fluid and letting it dry out, then WD40 and some 3 in 1 oil, bingo. Promlem solved.

I hope this helps out others in the future as this was a pig to diagnose.