Lotus Elan

Interior light wiring

PostPost by: EEED » Sun Jul 29, 2018 1:32 pm

Hi All,

I hope someone can help. I have recently purchased a new courtesy/interior light for my early S3.The new light has black connection (the earth), a brown connection which I assume is equivalent to the original loom's purple, and a brown and white connection which I assume is equivalent to the original purple and white.

The car has been fitted with a battery cut off switch, so as the courtesy light won't function unless the battery is connected, I can't see any point in retaining the courtesy light switches in the door apertures. Nor does there seem to be any benefit in having a light switch for the interior light on the dash because the new light has one already built-in and I can use the vacant hole in the dashboard for a switch for the electric screen washer.

The loom has two purple and white wires in a spade connector which I assume connect to the courtesy light switches and a black earth wire bound with them, presumably the courtesy switch earth also with a spade connector . There is separate purple wire and a separate purple/white wire, both of which have bullet connectors.

How do I connect the new light to the loom given I want to remove the dash interior light toggle switch and that I see no need to connect up the courtesy light switches?

Logically the brown connection on the new light should connect to the purple wire in the loom. Do I need to add a new cable to earth and do I need to install an in-line fuse? What do I do with the brown/white connection on the new light?

I hope this all makes sense!

Thanks in advance for any advice.

Paul
Paul

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PostPost by: stugilmour » Thu Aug 02, 2018 3:28 pm

Paul, I think I understand your dilemma.

In stock form the Purple/White essentially forms a daisy chain that connects to the two door switches, the dash switch, and any installed interior lights (my Plus 2 and Elan Coupes have lights in the C Pilar). If any one of the switches goes to ground all of the lamps light up.

Each light is supplied by an individual Purple, Hot at all times, fused supply wire.

If you are eliminating the dash and door switches this daisy chain Purple/White switch wire is not required.

The front mounted lamp housing with the included three position switch usually has a Purple, Hot at all times, fused supply wire, the Purple/White switch wire, and a Black ground. The idea is placing the housing switch in the ON position grounds only the bulb in the lamp housing, not the Purple/White switch wire. Therefore only the one lamp housing lights up, not the C pillar lights.

As I understand you are only going to have the one courtesy light with only it?s own internal switch, you will only require the Purple, Hot at all times, fused supply wire and the Black ground to the lamp housing. I think from memory the Black typically connects to a ground lug on one of the mounting screws. The Purple supply can be connected to either or both switch positions on the lamp housing.

There may be a slightly easier way to wire it, but a bit of a bodge and depends on the details of the lamp housing included switch.

Jump the Purple/White to ground at one of the existing switches (the dash switch is probably the easiest as you are removing it anyway and there will be a Black ground already attached to the switch).

Connect your new lamp housing as you intended, Brown to Purple, Brown/White to Purple/White.

Manipulate the housing switch between the OFF position and the WILL LIGHT UP WHEN THE DOOR IS OPENED position to operate it.

This of course assumes the switch works this way on your lamp housing and you are indeed only installing one interior lamp housing with it?s own included three position switch.

You can easily test if this configuration will work by wiring up the lamp housing and manipulating the included switch with one of the doors open or the dash switch set to ON. If you can?t get the new housing to turn off, unfortunately it ain?t going to work as described.

HTH

Stu
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PostPost by: EEED » Mon Aug 06, 2018 5:56 pm

Stu,

Thanks. I've just seen your reply.

I worked out the way to wire the new light by testing the connections on a spare battery (once I'd got the crocodile clips on the test cables to actually connect properly). As I've deleted the dash switch and haven't connected in the courtesy light switches, I just wired the earth to the nearest earthing point and connected the purple cable to the brown one on the new switch. The light now just switches on/off from its own built-in switch. I put the now 'spare' purple/white into one side of a connector and thoroughly taped over the other end of the connector. Similarly, I securely taped up the unused ends of the courtesy light switch cables and the purple/white lead in the loom.

Everything is working fine.

Thanks again.

Paul
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PostPost by: stugilmour » Wed Aug 08, 2018 12:11 am

Excellent. Glad it worked out

Stu
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