Lotus Elan

Ignition switch replacement

PostPost by: jimj » Mon Jun 03, 2019 8:14 am

On our S3, sometimes, for example yesterday, my ignition switch gets really hot, though later on it was cool. I`ve previously cleaned up all the contacts and they, and the wiring all seem OK but something`s not right. I see a new switch is not expensive but do I need a new barrel too? If not, how do I remove and refit the existing barrel?
Jim
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PostPost by: oldelanman » Mon Jun 03, 2019 9:41 am

Hi Jim,
It sounds like you have a high resistance inside the switch, I had a similar problem with a large voltage drop across the switch and had to replace it. Have a look here......
viewtopic.php?f=38&t=44446
You can reuse your lock barrel, it's held into the switch by a small brass spring loaded button which you access via a hole in the switch casing .. push it in and pull the lock out using the key.
img_20190518_163433.jpg and

Depending on the switch you get it may need a slight modification, I went for a "Genuine Lucas" (haha) and the threaded section has 2 small flats instead of the larger single flat of the original so needed addressing with a file to fit the D hole in the dash.
Roger
S4 DHC
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PostPost by: jimj » Tue Jun 18, 2019 12:26 pm

Thanks for that, today I got round to it. As you can see in the pic. hopefully, there are no markings on the plastic around the terminals on the new switch. I changed them over one by one but now turning the key to the left puts on the ignition light, centre is off, and right turns on the ignition and the starter motor, running continually. With the power off I can see a further turn is spring loaded. Clearly the terminals are in different positions but which?
Jim

P.S. I started with the single spade, the same, directly in line with the hole.
Attachments
dsc00637.jpg and
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PostPost by: oldelanman » Tue Jun 18, 2019 1:36 pm

Hi Jim,
Your switch looks identical to my replacement and sounds to operate mechanically as per the original .....
AUX - OFF - IGN - START .... on mine the terminal numbers are moulded into the plastic but are very difficult to read. Comparing to the wiring diagram in the workshop manual ..... clockwise starting with the single spade next to the hole in the case you should have 3, 4, 1, 2
I found it extremely tricky removing and refitting the connections due to the confined space, the short wires and failing eyesight ..... sounds like you may have just got a couple of the connections mixed up. Maybe this will help....

Working CLOCKWISE starting with the single spade next to the hole in the case as #1 and numbering each spade terminal individually, here's what you should have..

Terminal ............Wire colour ..............Function
1 .......................White/Red ..................Starter
2 ...........................................................Spare
3 .......................White/Purple...............Cigarette lighter
4 .......................Brown..........................Windows
" ...................... Brown .........................Hazards
5 ...................... Brown/Blue..................+12v supply from control box
6 .......................White...........................Fuse box Main fuse
7 ......................White...........................Ignition coil

Good luck !
Cheers

Edit .. just noticed you have an S3 , above info relates to my S4 but the switch wiring is the same according to the 2 wiring diagrams.
Roger
S4 DHC
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PostPost by: joe7 » Tue Jun 18, 2019 6:20 pm

One thing I did when replacing the IGN switch was to bench test the terminals. As such I found that the AUX terminal was also hot in ON & IGN. So I connected my electric fuel pump and manual fan that have off/on switches to the AUX terminal. This way I can run the pump to fill the carbs w/o having the IGN on and if I want a cool down simply turn the fan on, pump off.
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PostPost by: jimj » Wed Jun 19, 2019 11:49 am

Thanks Joe, I`ve just popped out to connect it up and test it. I`d reconnected the old switch in the original positions so disconnected those, ooer, I then found out my wiring colours to be different. I`ve no reason to think they`re not original.
I`ve got a red and white, a thicker brown and blue, 2 whites to the same connector, a single white, 2 purples to the same connector, and a white and green. Which is what and where?
Thanks in advance.
Jim
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PostPost by: oldelanman » Wed Jun 19, 2019 1:22 pm

Jim,
Most of your colours tie up with what I've posted above so, numbering your terminals as before I would suggest .....

Red/white ....terminal 1 - starter
Brown/blue...terminal 5 - 12v supply
Double white..terminal 7 - coil + ign warning light
Single white.....terminal 6. - supply to main fuse

That leaves.....
Double purple .... most probably corresponds to my double brown .... terminal 4 - hazards + windows (permanent live)
White/green ... most probably corresponds to my white/purple ... terminal 3 - auxiliaries (radio, cigarette lighter etc via second fuse in fuse box.

Hope that helps.
Roger
S4 DHC
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PostPost by: jimj » Wed Jun 19, 2019 1:26 pm

Thanks Roger, not Joe, I`ll give it a go later.
Jim
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PostPost by: jimj » Wed Jun 19, 2019 2:51 pm

Ee bye gum (not bah, that`s Lancashire) that`s it Roger. Thankyou and thank lotuselan.net, it`s invaluable for just such conundrums. It`s done and working.
Jim
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PostPost by: oldelanman » Wed Jun 19, 2019 4:23 pm

Well done Jim. Glad you got it sorted :D
Roger
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