Lotus Elan

+2 Park/Interior Switch Logic (or lack of it)

PostPost by: JGeezer » Tue Jan 24, 2017 8:04 pm

So I'm trying to sort out what happens with the park and panel switches in my Federal +2 basket case restoration ("mid" fascia, four gauges and rocker switches). Both the park and panel switches are three position. I have the user's manual, which is basically useless and makes me crazy.

1. With each of these switches in the three positions, what is supposed to happen?

2. The users manual says the "lighting" switch (whichever of them that is) is "centre-based", meaning it will return to center like the window switches. Mine do not, they are just three position switches.

Been going a little nuts trying to get the panel lights to come on at the right time, the "sidelight relay" doesn't make sense to me. But if I knew how things were SUPPOSED to behave, maybe I could sort this out.

Thanks for taking pity and helping. Nothing worse than being an actual electrical engineer trying to figure out British wiring logic (or lack of it).
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PostPost by: jono » Tue Jan 24, 2017 8:08 pm

Mike Duff on here (another electrical engineer) knows the score with these and helped me wire mine up.

I recall Mike mentioned this switch is 'foxy', which is a nice way to put it. :D

Try sending Mike a PM, unless he spots this post.

Jon
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PostPost by: JGeezer » Tue Jan 24, 2017 8:21 pm

Thanks!
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PostPost by: miked » Wed Jan 25, 2017 11:13 am

PM replied to.
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PostPost by: gus » Wed Jan 25, 2017 1:04 pm

The panel switch turns on the interior lights in one position and turns the dash lights off in the other, dunno why

if you have the 2 position momentary for the sidelights it is a self holding relay which is a little complicated to explain but not crazy to wire
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PostPost by: JGeezer » Wed Jan 25, 2017 1:51 pm

Thank you Mike and Gus. It looks like I have to source the correct sidelight switch, mine somehow is definitely a three position of some sort (I did refurbish them myself, most likely I am to blame). The latching logic sketched by Mike makes sense!

For you struggling forum searchers in the future, I'll copy Mike's entire (excellent) PM here:

Hi John,

Please have a look at this:
lotus-electrical-f38/side-light-latch-circuit-t22484.html

I sold my plus 2 about 2 months ago so don't have any car to go and look at now. Working from memory!

I think you may appreciate the above schematic diagram with explanation rather than silly wiring diagrams. I am not sure if Federal wiring is different but on UK Plus 2S (with 3 fuse boxes) the side light circuit does have a 3 position switch sprung to centre. See contact configuration. The relay is latched by its own contact via a bottom push of the switch or head light micro switch operation. It is de-latched by pressing the top of the switch. A simple circuit very poorly drawn by Lotus.

As regards the other switch I think that it was a 3 position stay put (so you perhaps have the right one). I think that pushing it up (at the top)allowed the gauge lights to operate from the side light power circuit (had to be on, so interlocked). Switch left in this position all the time. Then pushing it down (at the bottom) brought on the interior lights via grounding the circuit. In mid position neither gauge lights nor internally operated interior light were on. However the door contact still operate the interior lights. This would need verifying, I was on it all but not played with the Plus 2 for a good while. PM Jono and ask him about this switch. As I recall looking at a map at night was the only time I pressed the switch down to see.

I ended up starting with the diagram and a multi-meter and I drew a table of what connection made and broke against the numbered switch connections. You need to do all permutations as you will be surprised as to what connects with what.

The wiper switch is fun as it feeds out H & L positive and also has a circuit for an electric back emf brake when pushed to off. Wipe has perm + for self park.

PS if you strip the rocker switches down to clean/repair be careful to lift the tops from above so you can see which way the moving contact lay as if you don't you will chase your tail.

Hope this helps.

Regards Mike
Last edited by JGeezer on Tue Feb 14, 2017 8:18 pm, edited 1 time in total.
J Geezer
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1969 Elan+2 Federal
(Past MGA, MGB, TR6, AH 3000 BJ8, XR4ti, BMW E39 540i/6, Lola T644 ... )
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PostPost by: JGeezer » Wed Jan 25, 2017 9:21 pm

I'm getting a bit less sure. My chassis 0964 is early, with non-failsafe headlights. This seems to be the failsafe wiring (introduced chassis 1174), which is the only system the shop manual deems fit to describe.

My early wiring has entirely different wire colors at the sidelight switch (blue/red, purple, red) and mostly different on the side light relay.

Hmmm.
J Geezer
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1969 Elan+2 Federal
(Past MGA, MGB, TR6, AH 3000 BJ8, XR4ti, BMW E39 540i/6, Lola T644 ... )
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PostPost by: crannyr » Fri Jan 27, 2017 1:46 pm

I have the switches you are looking for and can help sort out the wiring with wiring diagrams for all models and some experience redoing my own system and a few others. Unfortunately I am out of the area for awhile but give me a call and we can talk about what you need. you should have my number, if not send me a PM
Rick
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PostPost by: JGeezer » Fri Jan 27, 2017 1:51 pm

Thank you everyone, especially Mike & Gus, this is sorted. The relay logic is in fact the same, but the early loom wire colors are different.

Thanks!
J Geezer
2004 Cadillac CTS-V
2003 Corvette Coupe
1969 Elan+2 Federal
(Past MGA, MGB, TR6, AH 3000 BJ8, XR4ti, BMW E39 540i/6, Lola T644 ... )
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PostPost by: JGeezer » Tue Feb 14, 2017 8:25 pm

One more step, please! I have the sidelight relay working as it should from the dash on/off switch, latching at on and staying latched until switch off.

BUT - this means the sidelights go on with the headlight micro switch (good), but stay on until the dash park light switch is turned to off. Reading the nice schematic from miked, that is indeed how it is wired. Is this really how +2 sidelights are supposed work? You can turn them on from either the switch or by raising the lights, but either will latch them on until you separately turn them off at the switch?

I'm willing to believe this was actually intentional British logic (intended to maximize flat batteries, I guess), but would appreciate confirmation of that.

Thanks yet again.
J Geezer
2004 Cadillac CTS-V
2003 Corvette Coupe
1969 Elan+2 Federal
(Past MGA, MGB, TR6, AH 3000 BJ8, XR4ti, BMW E39 540i/6, Lola T644 ... )
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PostPost by: stugilmour » Tue Feb 14, 2017 8:33 pm

JGeezer wrote:One more step, please! I have the sidelight relay working as it should from the dash on/off switch, latching at on and staying latched until switch off.

BUT - this means the sidelights go on with the headlight micro switch (good), but stay on until the dash park light switch is turned to off. Reading the nice schematic from miked, that is indeed how it is wired. Is this really how +2 sidelights are supposed work? You can turn them on from either the switch or by raising the lights, but either will latch them on until you separately turn them off at the switch?

I'm willing to believe this was actually intentional British logic (intended to maximize flat batteries, I guess), but would appreciate confirmation of that.

Thanks yet again.


Yes, this how all the momentary switch ones work. Can't help with why, although I speculated maybe to use them as parking lights?. Not a big deal once one is used to it I suppose. :D

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PostPost by: JGeezer » Tue Feb 14, 2017 8:49 pm

stugilmour wrote:
JGeezer wrote:One more step, please! I have the sidelight relay working as it should from the dash on/off switch, latching at on and staying latched until switch off.

BUT - this means the sidelights go on with the headlight micro switch (good), but stay on until the dash park light switch is turned to off. Reading the nice schematic from miked, that is indeed how it is wired. Is this really how +2 sidelights are supposed work? You can turn them on from either the switch or by raising the lights, but either will latch them on until you separately turn them off at the switch?

I'm willing to believe this was actually intentional British logic (intended to maximize flat batteries, I guess), but would appreciate confirmation of that.

Thanks yet again.


Yes, this how all the momentary switch ones work. Can't help with why, although I speculated maybe to use them as parking lights?. Not a big deal once one is used to it I suppose. :D

Stu


I would think good logic would be on and off with headlights, or optionally latch on with the switch to use as parking lights until switched off. If the wire from the micro switch went directly to the lights, that's how it would work (but I'm guessing there are lighter and heavier wire gauges involved, and you want the actual current to the lights to come off the heavier wires on the relay).
J Geezer
2004 Cadillac CTS-V
2003 Corvette Coupe
1969 Elan+2 Federal
(Past MGA, MGB, TR6, AH 3000 BJ8, XR4ti, BMW E39 540i/6, Lola T644 ... )
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PostPost by: gus » Wed Feb 15, 2017 12:14 pm

That is correct, the wires, plus the little micro switch would be undersized to handle that load.

Never considered it a problem
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PostPost by: stugilmour » Wed Feb 15, 2017 3:21 pm

Agree with Gus. I suppose you could add a power relay to the circuit so you are not feeding the side lights from the microswitch. IIRC the dash lights are also fed from the side light circuit, so it is a fair load.

I considered doing it this way when I rewired my car. I had used up all the available relay slots in the boxes I had selected, so left it with the somewhat quirky stock configuration. Pretty much used to it now.

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PostPost by: JGeezer » Wed Feb 15, 2017 5:38 pm

It seems my topic title (above ^) was spot on! :lol:
J Geezer
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(Past MGA, MGB, TR6, AH 3000 BJ8, XR4ti, BMW E39 540i/6, Lola T644 ... )
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