Lotus Elan

Factory Grounding of headlight relays

PostPost by: awatkins » Mon Apr 05, 2021 4:54 am

My S3-SS was ground-up restored before I purchased it and I keep finding interesting deviations from original. I have just discovered that neither the main headlight nor headlight flasher relay cases are grounded. I've looked at many photos of this area on other Elans but I can't quite make out how this was originally accomplished. In some cases it appears the relay's mounting ears are overlapped so that they are grounded to each other, and then I assume a wire connects the rear-most relay to the LHS ground point on the radiator support. In other cases they are all physically separated, but in that case I've never detected a ground wire running from relay to relay.

I would appreciate some guidance on how the factory likely arranged grounding for these relays.

Thanks in advance,
Alan Watkins
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PostPost by: oldelanman » Mon Apr 05, 2021 8:42 am

The case of the relay does not need to be earthed as there are no electrical connections between the internals and the case. The headlamp relay coils are grounded through the microswitch on the headlamp pod to ensure the lamps go off when lowered.

lucas-6ra-relays.jpeg
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PostPost by: awatkins » Mon Apr 05, 2021 4:55 pm

The relays I am working with have only one W terminals, as is shown on the S1/S2 wiring diagram (harness is autosoarks replacement which follows that diagram).
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PostPost by: oldelanman » Mon Apr 05, 2021 5:49 pm

awatkins wrote:The relays I am working with have only one W terminals, as is shown on the S1/S2 wiring diagram (harness is autosoarks replacement which follows that diagram).


In that type of relay the C2 and W2 terminals are connected internally as shown below but the case still does not need to be earthed for the relay to function. The relay coil is grounded from terminal W1 via the microswitch on the headlamp pod as shown in the S2 wiring diagram you refer to.

lucas-6ra-relays 2.jpeg and


s2-wiring-diagram.jpg
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PostPost by: awatkins » Mon Apr 05, 2021 10:43 pm

Live and Learn. Thanks!

BTW what was the original source for the relay diagrams you included?
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PostPost by: oldelanman » Tue Apr 06, 2021 8:21 am

awatkins wrote:Live and Learn. Thanks!

BTW what was the original source for the relay diagrams you included?


A Google search for "Lucas 6RA Relay" brings up loads of images, I copied those from a Jag site as they were particularly clear. Most of the Auto electrical retailers like Holden, Auto Electric Supplies and Rimmer Bros in the UK also include the information in their on-line catalogues.
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