Lotus Elan

Elan Sprint horn wiring

PostPost by: Mrozik » Fri Feb 19, 2021 5:47 am

Hi
I recently bought a 1972 Sprint where the electrics in the engine bay had been renewed badly. The connections to the air horn compressor have, for some reason, been by-passed. Can someone help me with the original wiring?
Thanks for the help
John
Mrozik
Second Gear
Second Gear
 
Posts: 53
Joined: 19 Feb 2020
Location: England

PostPost by: Mrozik » Fri Feb 19, 2021 8:02 am

Just wanted to add that what I am really looking for are the colours of the wires that originally powered the horn compressor. Thanks
Mrozik
Second Gear
Second Gear
 
Posts: 53
Joined: 19 Feb 2020
Location: England

PostPost by: Andy8421 » Fri Feb 19, 2021 9:32 am

John,

I only have a S4 wiring diagram, I haven't seen one specifically for the Sprint - although one possibly may exist.

The wiring diagram in the manual is difficult to read and the horn wiring is not clear - the air horn compressor doesn't appear and there is an associated relay shown as 'optional' with unmarked wires going to it.

The wires that can be identified as going to the horns are PB - purple and black, this goes to the horn button in the centre of the steering wheel, and P - purple which goes to the fusebox for the power feed.

My Sprint's wiring was dreadful, I have replaced much of the wiring to the relays and the colours aren't original I am afraid. If you don't have a horn relay, you will need one as the compressor draws a lot of current.

Andy.
Andy8421
Fourth Gear
Fourth Gear
 
Posts: 507
Joined: 27 Mar 2011
Location: Surrey, UK

PostPost by: Mrozik » Fri Feb 19, 2021 10:27 am

Andy

That's really useful. I have a number of purple wires - one in fact goes nowhere so I suspect that's the orginal air compressor unit one. There seems to be a relay present with a purple wire connection so I'll start there.

Glad to hear that mine is not the only one with crazy wiring.

Thanks
John
Mrozik
Second Gear
Second Gear
 
Posts: 53
Joined: 19 Feb 2020
Location: England

PostPost by: oldelanman » Fri Feb 19, 2021 10:41 am

Hi John,
Like Andy I only have the S4 diagram but mine does show the compressor. The current draw is quite high so you may want to add an additional feed to the relay from the fuse box and just use the original horn feed to switch the relay.


Air Horn Wiring.jpg and
Roger
S4 DHC
oldelanman
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1746
Joined: 02 Jan 2008
Location: Dorset UK

PostPost by: Andy8421 » Fri Feb 19, 2021 12:29 pm

oldelanman wrote:Hi John,
Like Andy I only have the S4 diagram but mine does show the compressor. The current draw is quite high so you may want to add an additional feed to the relay from the fuse box and just use the original horn feed to switch the relay.


Air Horn Wiring.jpg


John,

I have the same wiring diagram as Oldelanman, but nowhere near as clear. The 'Horn comp when fitted' on mine is just a splodge. The manual came with my car. I was told it was genuine Lotus, but I suspect it is a dodgy photocopy.

Even Oldelanman's much clearer wiring diagram doesn't give much away when it comes to the wiring of the relay. If you need more help, post the details of your relay when you have figured out which one you want to use, and I can help with the connections.

Andy.
Andy8421
Fourth Gear
Fourth Gear
 
Posts: 507
Joined: 27 Mar 2011
Location: Surrey, UK

PostPost by: Mrozik » Fri Feb 19, 2021 12:34 pm

Thanks all
I will do a bit fidling and probably by trial and error work out what goes where. I'll post the results in due course (got the c head to re-install at the moment)
Cheers
John
Mrozik
Second Gear
Second Gear
 
Posts: 53
Joined: 19 Feb 2020
Location: England

PostPost by: geni » Sat Feb 20, 2021 10:22 am

as long as there is darkness! I would need an understandable and clear wiring diagram for the S3 well detailed for my eyes so if we can see it!
geni
Second Gear
Second Gear
 
Posts: 150
Joined: 30 Dec 2014
Location: FRANCE

PostPost by: ericbushby » Sat Feb 20, 2021 11:24 am

Hi Geni,
I can send you a wiring diagram for the S3 if you want.
I get several copies printed at A3 size by the local print shop and highlight the circuit I am working on.
I am told it is still quite readable at A2 size.
If you send me your email address by PM, I will send it. Don`t put emails on this open forum.
Eric in Burnley
S3SE DHC
ericbushby
Fourth Gear
Fourth Gear
 
Posts: 962
Joined: 13 Jun 2011
Location: east lancashire

PostPost by: Mrozik » Sat Feb 20, 2021 2:17 pm

The plot thickens. I've just found a "separate horn button" fixed to the underside of the dashboard. I'm guessing the previous "master electrician" couldn't work out how to connect the horn push on the steering wheel. I can't believe its that difficult, is it? Attached photos of what I have.
Grateful for the assistance restoring the system.
Thanks
Attachments
horn 1.JPG and
horn 2.JPG and
horn 3.JPG and
Mrozik
Second Gear
Second Gear
 
Posts: 53
Joined: 19 Feb 2020
Location: England

PostPost by: mbell » Sat Feb 20, 2021 2:43 pm

The wheel switch works by bridge the ring shown with the steering column that is grounded.

The standard wheel/hub used a spring loaded "pencil" to contact the ring and run to switch input. The switch then grounds via the hub/column. After market may have a different setup.

The other common issue is broken/missing bridge cable that the steering column flex joint near there rack. This can break the earth connection on the column and so the horn working.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
mbell
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1878
Joined: 07 Jun 2013
Location: Austin, TX (UK Ex-pat)

PostPost by: Mrozik » Sun Feb 21, 2021 5:04 am

Thanks for that - got it. The bridge cable is missing so my guess is that's why the horn was re-routed. Do you know what colour wire feeds the ring?
Cheers
Mrozik
Second Gear
Second Gear
 
Posts: 53
Joined: 19 Feb 2020
Location: England

PostPost by: oldelanman » Sun Feb 21, 2021 9:52 am

Mrozik wrote:Thanks for that - got it. The bridge cable is missing so my guess is that's why the horn was re-routed. Do you know what colour wire feeds the ring?
Cheers

In addition to the bridge wire across the column flexible coupling the rack itself should be earthed....

Steering rack earth.png and


The feed wire to the horn slip ring should be Purple/Black.

You should find three bullet connectors joining the column switches and horn push to the main loom ...here's how my S4 column wiring is connected ... note the mismatch of wiring colours for the dipswitch.
Steering Column Wiring Connections (2).jpg and
Roger
S4 DHC
oldelanman
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1746
Joined: 02 Jan 2008
Location: Dorset UK

PostPost by: Mrozik » Sun Feb 21, 2021 11:32 am

Many thanks. That's exactly what I needed.
Mrozik
Second Gear
Second Gear
 
Posts: 53
Joined: 19 Feb 2020
Location: England

Total Online:

Users browsing this forum: No registered users and 2 guests