Lotus Elan

Dashboard / Instrument Light Woes

PostPost by: chickenstock10k » Sat Feb 16, 2019 2:59 am

I've been struggling to figure out how to get my instrument lights to work, when I turn the headlights on, in my Elan +2. My challenge has been made a bit more difficult by the fact that the previous owner took off all of the dash labels when they refinished the dash board. This has been made even more difficult by the fact that I can't any photos of a dashboard that looks similar to mine. See below:

file-58.jpeg and


However, I seem to have stumbled onto a clue. When I press the the parking light switch down, circled in red:

dashlight-button-down.jpg and


The instrument lights seem to come on. When I look behind the dash at the light switch I can see where the vacum tubes are connected but it doesn't really look like there are any wires attached. Should there be something? Also, might tail lights don't come on when I turn on the headlights either and now I am beginning to wonder if the issues are linked.

I've tried looking at the wiring diagrams but its a little hard to read without the visual clues...

Bonus question - When I press the far right upper switch, the far right blue light comes on. What is that?
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PostPost by: mbell » Sat Feb 16, 2019 3:18 am

The instrument lights are on separate switch, that's normally label "panel". It's should be the same one that turns on interior lights. It has three positions, off, instrumentation lights on, interior lights on. Not sure if the exact position in your dash layout.

I'd guess the blue light and switch is for heated rear screen.
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PostPost by: chickenstock10k » Sat Feb 16, 2019 3:54 am

So the interior light switch is, I believe, the second to the far right. Next to the button that turns on the blue light. If I push it all the way down it turns on the interior light. In the middle it does nothing and all the way up it does nothing.

However, when the panel light switch is the middle position and I push down on the parking light switch, the instrument lights come on. When I push the panel button into the "off" position and I push down on the parking light button, the instrument lights come on. This makes me think that the panel switch is working correctly.

To ask a very dumb question: should the instrument lights only come on when the headlights are on?
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PostPost by: mbell » Sat Feb 16, 2019 1:52 pm

Sounds like you've found it. Switch is also by rear screen switch on my car (later different dash), see pic.

Yes they only illuminate when the exterior lights are turned on. Again on my later car with different wiring but no reason to expect different behaviour.

Sounds some wiring issue, always start with grounds on lotus...
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PostPost by: chickenstock10k » Sat Feb 16, 2019 2:47 pm

Should there be a wire coming rom the back of the light switch that connects to the dash lights?
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PostPost by: stugilmour » Sat Feb 16, 2019 5:22 pm

chickenstock10k wrote:Should there be a wire coming rom the back of the light switch that connects to the dash lights?


Quick answer is no, I don’t think so. The side light wire comes from the side light relay, not the switch.

I would suggest we get the side light circuit working first.

Here is a link to a PowerPoint slide I did up regarding side light intermittent switch and relay. Tricky circuit. Have you looked this over?

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

I am online right now if you want to discuss.

HTH

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PostPost by: stugilmour » Sat Feb 16, 2019 5:35 pm

chickenstock10k wrote:So the interior light switch is, I believe, the second to the far right. Next to the button that turns on the blue light. If I push it all the way down it turns on the interior light. In the middle it does nothing and all the way up it does nothing.

However, when the panel light switch is the middle position and I push down on the parking light switch, the instrument lights come on. When I push the panel button into the "off" position and I push down on the parking light button, the instrument lights come on. This makes me think that the panel switch is working correctly.

To ask a very dumb question: should the instrument lights only come on when the headlights are on?


The switch with th blue light is the rear screen heater switch.

The switch next to it is indeed the panel and interior switch.

The panel lights should come on momentarily when you press the side light switch momentary switch to the on position only when the panel interior light is in the on position. From your description something seems incorrect, possibly with panel light supply. Ie I don’t think the panel light switch is behaving correctly.

That said, if the tail lamps are not staying on, I would focus on that issue first.

Quick check. You may need assistance. When pressing side light momentary switch to on, do the front ‘parking’ lights and the tail lights come on momentarily? They should.

The side light relay acts as a latching relay and should keep them on. This does not seem to be working on your car. Examine side light relay, which should be located on the passenger side of the heater box.

Side lights (ie tail lights and front ‘parking’ lights) should also come on and stay on when headlights are on. Is this happening?

HTH

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PostPost by: chickenstock10k » Sat Feb 16, 2019 7:02 pm

Stu, thanks for the help.

So, when I push the side light switch the tail lights and the front lights come on. As a note, I have to hold the side light switch down. It doesn’t click down and stay in position.

Does this offer a clue?
Last edited by chickenstock10k on Sun Feb 17, 2019 4:12 pm, edited 1 time in total.
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PostPost by: stugilmour » Sat Feb 16, 2019 7:26 pm

Yes. Huge clue.

This is a quirky circuit. The intermittent sidelight switch is correct for Federal cars like mine, the Veg, and I guess yours. I had asked a few times here if the non-Federal guys got this circuit, but still not sure on that part.

OK, so the sidelight relay is either screwed, wired incorrectly, or both. The sidelight relay is what keeps the sidelights on. The fact that they come on momentarily when you press the spring loaded switch down is huge, as it narrows down the issue to the relay. The lights themselves are probably wired correctly.

Look at the PowerPoint slide as I tried to explain the circuit there. The operation of the circuit is covered in the WSM as well. If you can’t read/open the PowerPoint slide let me know and I will make a PDF.

My guess is a previous owner got confused on the sidelight relay function and has moved the wires around. Or it could have failed, but check wiring first. Anyway, the key is the jumper wire on the relay that connects the trigger wire to the relay output terminal. This is what ‘latches’ the circuit on because the trigger coil is supplied from the relay output terminal. The circuit is turned off by momentarily breaking the power supply to the trigger coil, which ‘unlatches’ the circuit.

Once we get the sidelights to come on and go off with the sidelight switch, we then can function test that they come on with the headlight switch. Note this part is quirky. The sidelights do not turn off with the headlights; still need to press the sidelight switch to turn them off. “This is a feature nit a bug”. In fact, yo could turn on the headlights and see if the sidelights come on when the headlights are on; that would also be a good check.

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PostPost by: stugilmour » Sat Feb 16, 2019 7:46 pm

Here is a PDF of the PowerPoint slides
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Sidelight Switch Circuit.pdf
PDF version of PowerPoint slides describing Federal Sidelight Switch circuit.
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PostPost by: The Veg » Sat Feb 16, 2019 10:03 pm

+1 On what Stu says.

Also I can confirm the rear screen switch & light. My car has those and the light comes on but my rear glass has no heating lines, nor does the car's wiring have any leads to connect to such. Maybe I'll find some cool accessory to connect to it like a smokescreen or a missile launcher.
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PostPost by: chickenstock10k » Sat Feb 16, 2019 11:07 pm

Ok, another silly question, is there and easy way to get the headlight switch out of the dash so that I have a little more access to investigate. I’d have thought the black pull button would screw off but it didn’t seem to budge and I was worried about forcing it.

Can not thank you enough for the help. I have no idea how I would have sorted this solo...
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PostPost by: stugilmour » Sat Feb 16, 2019 11:14 pm

The Veg wrote:... My car has those and the light comes on but my rear glass has no heating lines, nor does the car's wiring have any leads to connect to such. Maybe I'll find some cool accessory to connect to it like a smokescreen or a missile launcher.


Same with mine. Must have been an option, or more likely switch & warning light were in anticipation of the Plus 2 S?

I am trying to find a copy of the Canadian Price List I have somewhere, but I don’t think it listed the heated rear screen as an option. Did include the sunroof as a dealer installed option though.

I used the switch for some driving lights placed behind the grille. I connected them to flash to pass on the high beam stock. Thinking of re-wiring them so they can be used as day time running lights (DTRL); we have had compulsory DTRL here for several years so running without lights is sort of rare now.

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PostPost by: stugilmour » Sat Feb 16, 2019 11:18 pm

It is difficult to remove with dash in place. Veg has done it more recently so he is best to ask. From memory, knob is removed with a little catch pin in the knob. Bezzle piece unscrews from around shaft and then pull switch out. It is a very large vacuum switch, with (probably) two microswitches attached to the outside. They are really fussy to get aligned right.

There is a thread on here with excellent photo’s of the light switch. I will try to find a link. This link shows a picture in a parts drawing. The microswitches are item 39 and there are two of them. Looks like it is post 50/1363.

http://www.lotuselan.net/wiki/BN_-_Body ... acuum_%2B2

What is your VIN? I am 50/2181. Note there were several running changes to the microswitch and vacuum switch setup in the Plus 2, but Veg and I have the version shown around item 39.

That said, have you checked the relay on the right heater box wall? Think that is where your issue is

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PostPost by: stugilmour » Sun Feb 17, 2019 2:48 am

Found this thread with a photo of the catch spring that retains the knob

lotus-electrical-f38/rookie-mistake-federal-headlight-switch-spring-pin-t43648.html#p309683

This thread has some pictures of the headlight pull switch with the attached microswitches. Not the thread I was thinking of though....

lotus-electrical-f38/rocker-switch-for-headlights-t15992.html#p80164

Anyway, suggest checking the sidelight relay wiring before removing headlight switch.

HTH

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