Lotus Elan

Dashboard test, electrical problems

PostPost by: billwill » Tue Aug 07, 2018 11:06 pm

Return to centre sounds like a window motor switch.
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PostPost by: stugilmour » Tue Aug 07, 2018 11:55 pm

Veg, your switch is correct for Federal Plus 2’s. Confuses others that have a different system.

This is actually the Side Light switch. It uses the side light relay (that we located earlier I believe?) that is typically mounted right side of heater box. It is shown in the Federal diagram, but it’s electrical connection is a bit cryptic in that diagram. I think the other schematic diagrams do not use this configuration so will just confuse you.

I will post a link to some threads that explain it all pretty well. We can easily figure it out when you get back to it.

Basically pressing one side of the springed rocker switch (or pulling the headlight vacuum switch) turns the side lights on and the relay latches them on. Pressing the other side of the springed rocker switch breaks the ground side of the latching relay and turns the side lights off (if the headlights are already turned off).

The weird deal to get used to is turning off the lights is a two step deal; push headlight vacuum switch in and then turn off side lights.

Details to follow. Later.

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PostPost by: stugilmour » Wed Aug 08, 2018 12:07 am

Here are some links from previous posts. Haven’t reviewed them in a while so ask if not clear....

Here are a few links. The last two have a PowerPoint diagram and write-up I did up and a pdf schematic Mike drew. Also references the page numbers in the service book where they describe how it should work.

lotus-electrical-f38/help-with-lightpod-microswitch-wiring-1968-plus-t30602.html

lotus-electrical-f38/side-lights-t17589.html

lotus-electrical-f38/help-with-lights-t30081.html

HTH Let us know how you get on and if you have any further questions.

Stu


HTH

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PostPost by: The Veg » Wed Aug 08, 2018 10:55 am

Thanks Stu, and you're right, that is a bit weird. I was especially confused because pushing the top of the switch did turn on the sidelights (exciting as I'd never seen them lit before!), but they shut off when I released the switch- which made me think that the switch wasn't right. So does the relay contain some special 'latching' circuit? I don't get how an ordinary relay would do this.
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PostPost by: stugilmour » Wed Aug 08, 2018 1:54 pm

It is an ordinary make and break relay. The wiring configuration is such it makes the lights stay on until the bottom part of the switch is pressed, which causes the ‘latched’ relay to loose the ground to the relay coil, opening the relay and turning off the lights.

When looking at the PowerPoint diagram, the coil terminals are called ‘winding’ or W1 and W2. The load terminals are called ‘contact’ or C1 and C2.

In essence the ‘latching’ is achieved by jumping the relay coil supply W1 to the load side of the relay switch terminals C2. Once power is momentarily supplied to the coil with the dash switch pressed, the load side C2 is hot and the jumper wire maintains power supply to the coil. Lights therefore stay on until the coil looses it’s ground at W2 thru the dash switch.

Wired correctly if you have the headlights on and press the bottom of the sidelight switch the sidelights and dash lights will turn off momentarily while the switch is pressed. However, as soon as the switch is released they come back on as the relay is powered through the sidelight microswitch and the relay coil ground is present thru the sidelight switch in the centre neutral position.

Note in our cars the two microswitches are located integrally to the vacuum switch rather than separate switches that are activated by the pod position. They sort of show this in the Federal diagram with a weird exception box for the microswitches; how they changed the loom to move the switches remains a bit of a mystery to me as I totally rewired the car anyway and cleaned that all up.

The two microswitches can be fussy to mount and adjust; not too bad with the dash out, more difficult when in place. Make sure the mounting screws are very snug. Pretty sure the North American part call-up for replacement microswitches (same as original but a superseded part number) is in one of the other threads if needed; one of mine needed replacement.

If you have inadvertently wired the sidelight relay in the conventional fashion (where the circuit allows a separate switching wire to activate the make and break relay controlling the load) it won’t work as a latching relay.

I will take another look at my old PowerPoint drawing and see if I can describe it better if needed. Took me a while to ‘get it’ for sure! The above is kind of from memory.

HTH

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PostPost by: stugilmour » Wed Aug 08, 2018 3:13 pm

Here is the PowerPoint diagram I did up.

Bit of a correction on the above after taking a closer look. The ground to the sidelight relay winding is constantly connected.

The circuit is turned off by momentarily interrupting the power to the sidelight relay when you press the bottom of the switch. I said above the switch was acting on the winding ground, which was my mistake. Note though that power to the sidelight relay is immediately restored with the switch in the neutral position only if the sidelight microswitch is electrically closed (vacuum switch pulled out).

Sorry for confusion.

Stu
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PostPost by: The Veg » Sat Aug 11, 2018 12:21 am

Thanks Stu! I'm on holiday in Colorado right now, but I'm looking forward to getting it all sorted.
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PostPost by: The Veg » Sat Aug 18, 2018 2:49 am

So far no luck with the sidelight problem. I found that the relay is clicking but not latching, and having W1 and W2 transposed and C1 disconnected (all unintentionally of course) wasn't the cause and correcting those had no effect. All relevant earths have been verified as good. Connections on the sidelight switch have been verified. I was double-checking the connections on the microswitches (which I'm still not completely certain about) when one microswitch basically fell apart.

I saw in the older threads Stu linked that equivalent items are difficult to source (in fact his link for a switch in one such thread is no longer valid). Anybody got current info about a compatible switch?
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PostPost by: 1owner69Elan » Sat Aug 18, 2018 7:13 am

If you are looking for a replacement for a microswitch and it is the same as the regular Elan, then this is an exact replacement except for the color:

https://www.parts-express.com/parts-exp ... h--060-600

I had to replace both of mine when the originals also cracked and fell apart.

3a569644-d97b-4543-94bd-5471cc41e20a.jpeg and
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PostPost by: The Veg » Sat Aug 18, 2018 12:52 pm

Thanks! Gotta love Parts Express; they keep coming up as the source for so many things I need in various areas both in the car and in other fields of endeavour.
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PostPost by: stugilmour » Sun Aug 19, 2018 2:41 pm

Excellent link for the microswitch! Also a good photo showing how the switch pair is mounted on the vacuum pull switch. Indeed that is the same as the Federal Plus 2.

Parts Express is way cheaper than the electronics supplier I used, and I bet shipping is easier as well on such a small order. Here is the part description in case the link goes south again...


Parts Express SPDT Snap-Action Standard Micro Switch
Brand:Parts Express|Part # 060-600

Standard micro switch.
Specifications:
• Current rating: 10A @ 125 VAC and 250 VAC
• Housing dimensions: 28.8 mm L x 15.8 mm W x 10.3 mm D
• Contacts: 3 • Approval: UL.


Veg, for sure replace both switches.

It may not be apparent, but each switch has a normally open and a normally closed set of contacts, along with a third common terminal. The sidelight circuit uses the normally open terminals.

For the latching action of the make and break relay, go you have the red jumper wire between the W1 and C2 terminals? Have you checked the relay works correctly as a make and break?

HTH and all he best.

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PostPost by: The Veg » Sun Aug 19, 2018 3:52 pm

I'm familiar with similar switches in industrial applications- in fact a slightly larger variant that also has a small metal lever that pushes the button is a familiar bit in one of the machines I service.

I did order two, and the shipping was more than the two switches! Total still have under $10 though so I can live with it. :mrgreen:

My relay does have the jumper and I've verified that all connections are correct, but it still won't latch: sidelights stay on only if I hold the rocker switch. Once the new microswitches are installed I'll play with it more.
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PostPost by: stugilmour » Sun Aug 19, 2018 5:50 pm

Humm, excellent.

Only other thing I can think of off hand is to validate the dash rocker switch terminal action as per the PowerPoint bullet points. I honestly can’t remember if terminal one is meant to illustrate the middle left terminal or the bottom terminal? At any rate, I made note of the terminals being hot or cold depending on switch action.

Best of luck. HTH

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