Lotus Elan

Wiring issues (again!)

PostPost by: Geoffers71 » Wed Nov 19, 2014 1:42 pm

Got a feeling this won't be the last time I'm asking numpty questions about my electrical wiring.....well I am only a simple....very.....mechanical engineer :oops:
I've had a search, but can't find anything that answers my particular problem. I'm wiring up the dash on my S2 using a new loom.
Issue no 1. According to the wiring diagram the wiring to the light switch consists of 4 wires; UN to terminal 1, R to terminal 4, UB to 6 and U to 8. My switch has only 4 terminals; 1,2,7 and 8 there are no terminals 3,4,5 or 6 and there is no evidence that they've broken off or anything, they're just not there, although there are flat copper plates where they might be. So....how do I wire this? Or is the switch wrong?

Issue no 2. The wiper switch on the S2 incorporates the manual washer pump. I have the 3 wires YG, RG and B, but in which order to connect to the 3 terminals marked A, E and F. No clues from the wiring diagram.

Sorry if these questions are so trivial and obvious. I can usually follow a wiring diagram, but I don't have that intuitive knack that electrickery guys seem to have.
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
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PostPost by: patrics » Wed Nov 19, 2014 8:05 pm

Hi,
All I would do is use a volt meter and buzz out the switch, I assume you will know which wire feed what so
Establish power in - with switch off nothing else connected
First click of switch should connect power to say side lights
Second click should for instance send power to dip / main switch but keep side lights live.
Anyway I'm sure you get the idea.
So basically buy a DVM and work methodically.

Hope that helps
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Steve
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PostPost by: Geoffers71 » Wed Nov 19, 2014 8:30 pm

Steve, thanks for trying to help, much appreciated ( I thought no-one cared :( :) ). However, the problem with the light switch, as I tried to explain, is that I cannot actually connect all of the wires to it. I have power in ( blue/brown) to terminal 1 and out at 8 (blue), but no tabs to fit the other two. Ironically it's more a mechanical problem if you see what I mean. The switch is the one supplied with the car so I'm assuming is correct, but I'm beginning to suspect otherwise.
BTW I have no power to anything as yet, need to connect things up first I presume.
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
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PostPost by: mbell » Wed Nov 19, 2014 8:46 pm

How many connection does the switch have? Can you provide a photo of the switch?

If the switch doesn't have enough connections then it is probably the wrong switch maybe a previous owner adjusted something. The light switch should provide output for sidelights, dipped beam and the dash lighting (R). Then a power in.

As Steve mentioned you should be able to work out the functionality of the switch using a meter, with out needing power. You just need to figuring out what connections are made with the switch in different positions from that you can work out how the switch should be connected. If you don't have a multi-meter it's well worth the investment as they aren't expensive these days.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: PeterK » Wed Nov 19, 2014 8:57 pm

In your post you mentioned 4 wires and 4 terminals.

In the absence of someone who knows, what Steve suggests is the the way forward. Using the multimeter, attach one probe to a switch terminal (chose any one, it doesn't matter which). Using the multimeter on continuity /bell setting, make a note of which (if any) of the terminals sound. Then switch the switch, and test all terminals again. Repeat this using each terminal as your main.

Let us know what you find and we'll work out which wire goes where
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PostPost by: PeterK » Wed Nov 19, 2014 8:58 pm

Drat, too slow again :D
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PostPost by: Geoffers71 » Wed Nov 19, 2014 9:14 pm

Thanks for the helpful suggestions. Thinking about it logically I'd just come to the conclusion that the switch must be wrong. As I said there's only tabs at 1,2,7 and 8 which do not correspond to the wiring diagram. A thought crossed my mind (normally a bit risky) and I delved into my electrical bit box. Most of the stuff in there is rubbish and collected over years. It includes a lot of stuff off my Scimitar which I completely restored a year or two ago and which shares a lot of bits in common with the Lotus (same vintage). Anyway there amongst the clutter was a toggle light switch with ALL terminals present, so problem solved. Yes I do have a multimeter and I do check all connectivity, especially in switches, before fitting. This switch works perfectly. :D I should have thought of this earlier, so sorry to have wasted people's time, just have to blame galloping senility :mrgreen: Still don't know how to connect the washer switch though :oops: I'll try experimenting with the multimeter.
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
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PostPost by: Geoffers71 » Wed Nov 19, 2014 9:48 pm

At the risk of embarrassing myself again I have another problem. The wiring to the Tacho is giving me a headache :roll: The wires to the main beam warning and the ignition warning lights are obvious, as is the RW instrument light, but the rest? First question; does the S2 have a voltage stabiliser? The wiring diagram for the S2 does not show one and there isn't one on the back of the Tacho or the Speedo or anywhere else. The S3 diagram shows a VoltStab on the Tacho and there appears to be a place there where one might fit, but is one needed or can I do without?
Secondly there is a white wire feed from the ignition switch that joins the Tacho at some point. There's a spade connector on the back of the Tacho, is this where it's supposed to join? The wire itself ends in a male bullet. Actually TWO white wires exit the loom at the Tacho position, one I've already mentioned, the one from the ignition switch, but I've no idea where the other, much longer white wire, is destined. Any ideas? Can't see anything likely on the wiring diagram.
Last edited by Geoffers71 on Wed Nov 19, 2014 9:58 pm, edited 1 time in total.
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
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PostPost by: patrics » Wed Nov 19, 2014 9:52 pm

The good thing about our cars and wiring is that the wiring diagram tells the story, so if there are x number of wires going to the switch then there are x number of wires going to the switch. If the wires join together at the switch then they are attached to the same terminal on the switch.
Spending time to think it through helps - power comes in - power goes out - switches something on - connects to earth
Keep the thinking simple

Regards
Steve
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PostPost by: rgh0 » Wed Nov 19, 2014 10:48 pm

Geoffers71 wrote:Secondly there is a white wire feed from the ignition switch that joins the Tacho at some point. There's a spade connector on the back of the Tacho, is this where it's supposed to join? The wire itself ends in a male bullet. Actually TWO white wires exit the loom at the Tacho position, one I've already mentioned, the one from the ignition switch, but I've no idea where the other, much longer white wire, is destined. Any ideas? Can't see anything likely on the wiring diagram.


The white wires are the feed to the coil from the ignition via the tacho that magnetically senses the current pulses in the wire. The other white wire should have a female bullet connector. On later tachos these wires plugged into connectors on the back of the tach. On earlier ones there was a metal sensor that projected out the rear of the tach that a couple of turns of the white wire was made around and then the two white wires joined.

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PostPost by: Geoffers71 » Wed Nov 19, 2014 11:12 pm

Rohan, I get it :roll: :D There IS a post sticking up from the back of the Tacho and I found a picture showing the white wire coiled through it. Both wires have male bullet ends, which means of course that they can easily be joined with a female bullet. Thank you very much, much relieved now. :D
But what, if anything, connects to the single spade connector that also protrudes from the back of the Tacho body?
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
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PostPost by: types26/36 » Wed Nov 19, 2014 11:15 pm

Geoffers71 wrote: First question; does the S2 have a voltage stabiliser? .


No stabiliser on S1 and S2 cars, I have also never seen a stabiliser on the three or four S3 cars I have worked on as they all had the S2 wiring but with the addition of the electric windows and switches.
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PostPost by: rgh0 » Thu Nov 20, 2014 1:05 am

There is a power supply to the tach electronics... the spade connector your referring to is may this ?
If it is actually direct to the metal case then its the earth connection for the tach. You need both for the tach to work

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PostPost by: Geoffers71 » Thu Nov 20, 2014 9:50 am

Thank you Rohan, very helpful yet again. Thought I'd double check, before I fry my new loom :lol: Here's the back of my tacho. I am connecting a 20 amp fuse in line before I switch on to avoid the fry up :mrgreen:
SNV32583.JPG and


On the left is the post around which the white wire is coiled, on the right is the spade tab which is insulated from the case. So this is where the live wire (green I'm assuming ) connects. The earth is a ring connector to the post that holds the tacho in the dash. I think this is right, but if anyone disagrees please get in touch.

Right two issues resolved, thank you very much everyone who contributed.
Onward and upward eh? There are bound to be other issues, but it's so useful to be able to share them with such helpful chaps.
For example, I might have an issue with the heater switch connections as the resister has only one tab free ( this is how I got the switch already connected) You can just see the resister behind the heater operating cable.
SNV32582.JPG and

There are 2 white wires from the heater motor, one is earth and I'm assuming the other connects to this free tab on the resister and that's it. Can anyone confirm that this is correct?
1965 Elan S2 (26/4726)
2002 Elise S2 (now sold :-()
1970 Scimitar GTE
"The older I get the better I was !"
Geoffers71
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PostPost by: rgh0 » Thu Nov 20, 2014 10:51 am

The two feed wires for the 2 speeds from the switch go to each end of the resistor. One thus feeds the fan power direct to the end where the fan power is connected to give the high speed and one runs through the resistor to the fan power giving the low speed.

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