Lotus Elan

Electrical help please..

PostPost by: Tonyw » Wed May 11, 2011 1:41 pm

Hi all,

I have a couple of questions on wiring for my S3 DHC (soon to be mobile)

I would like to take the stress out of my window switches by having the window motors controlled by relays rather that all the currant going through the switches I have looked in the archives in the hope that someone may have a schematic on how to wire this up to no avail as I am bit of a neo Luddite with wiring I need all the help I can get anybody.....???

My next question relates to the heater switch, I have the oblong three position switch (off, on , on) but the space/rebate for it behind the dash only allows for the single on, off switch so is my dash wrong or do I have the wrong switch? ( this switch is the same as my light switch) anyone able to let me know the correct switch part number? My heater fan is defiantly two speed

I am also looking for an alternative wiper switch which will also operate a washer motor (electric) I do not have the knob from the original switch so the offering from the Elan Factory is probably no good unless I can find a knob somewhere any suggestions for an alternative switch with a suitable knob? not that fussed about originality as long as it looks reasonably period.

Thanks in anticipation.

Tonyw
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PostPost by: billwill » Wed May 11, 2011 1:54 pm

You will probably need TWO relays per window, one for raising and one for lowering the window.
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PostPost by: Galwaylotus » Thu May 12, 2011 7:20 pm

Wiring in relays is straightforward. The terminals are ususlly marked 85, 86, 87 and 30. 85 and 86 are the coil connections. This is where you connect your existing switches as all they will do is to operate the coil. When the coil is energised it connects terminal 30 to terminal 87. 30 is the 12V supply from your battery or ignition switch. In the case of the S3 wiring diagram that should be a brown supply from the number 1 terminal on the ignition switch. You can pick up any convenient "always live" poiint to supply the 30 terminal. The 87 terminal is connected to the brown/green or brown/red cable that goes to the window motor. As stated above you will need two relays per window - one for down and one for up. Now that you have the power circuit connected, you need to be able to switch each circuit on. That's where the 85-86 coil comes in. Connect one side to earth (a black cable) and the other to the window switch terminals where the brown/green or brown/red cables were connected. When you operate the window switch, the coil circuit is energised and pulls the power switch closed sending current to the window motor.

Hope this helps. :wink:
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PostPost by: bast0n » Thu May 12, 2011 9:13 pm

My heater fan is defiantly two speed


I like defiantly!

I have never heard of an S3 with a two speed fan motor.

Any one out there know differently?


D
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PostPost by: billwill » Thu May 12, 2011 9:44 pm

bast0n wrote:
My heater fan is defiantly two speed


I like defiantly!

I have never heard of an S3 with a two speed fan motor.

Any one out there know differently?


D


My S3 had a two speed heater fan. But a later replacement motor has not been wired satisfactorily by tyhe garage's spark. So presently is running 1 speed. Unfortunately he clipped off the wire he thought was redundant so I haven't done anything about fixing that yet.
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PostPost by: billwill » Thu May 12, 2011 10:14 pm

Unfortunately the specific detail of the relaying method described by GalwayLotus wont work because the basic wiring of the window motors is as follows:

Image

The motor case is earthed (black wire) as a safety/anti-radio-interference measure but is not part of the activation circuit.

There is no power on the two green wires normally. To drive it one way there is +12v on one green wire (call it wire A) and the other (call it wire B) is earthed via the switch, to drive it the other way Wire A is earthed and wire B has +12volts.

It isn't clear if that can be done at all with single pole relays, so you might end up needing TWO DOUBLE-pole relays per window.

You will need a circuit like this:

http://www.datahighways.co.uk/photos/el ... elayed.jpg


Be mighty careful to avoid closing both relays at the same time as it will put a dead short across the battery & blow your fuse.

<later 13/4/13> I have removed that circuit from display, though you can still view it by clicking the link, because there is a much safer circuit shown in the messages below.
Last edited by billwill on Sat Apr 13, 2013 3:30 pm, edited 1 time in total.
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PostPost by: fatboyoz » Fri May 13, 2011 3:35 am

Tony,
This is how I did the window conversion to relays. You will need two relays per window with the following connections: 30, 85, 86, 87 and 87a.
Follow this procedure per door:
30: Main power out of the relay to power motor. One to the up side of the motor and one to the down. (trial and error will figure that one out).
85: Up control signal from the window switch to the up relay and down control signal from the window switch to the down relay. (These wires are the ones that power the motors pre modification).
86 & 87a: These should all be bussed together and go to earth. The earth wire that presently goes to the motor case should be a suitable earthing point.
87: Power to the relays. I used a thicker wire for this. I took a feed from the main power into the car (thick brown/blue wire, part of main loom where it connects to the interior loom) located above passenger's (L/H seat) knees. This is unswitched and unfused. I then ran this single feed to a fuse box (two fuses) that I attached to the underside of the horizontal part of the firewall above the passenger's knees. Two 10 amp fuses and an individual feed to each door completes the power supply.
My doors have speaker holes cut into them, so I was able to gain access to the inside of the doors to wire up the relays and then mount them inside and up out of any water that might get inside the doors.
Colin.

Tonyw wrote:Hi all,

I have a couple of questions on wiring for my S3 DHC (soon to be mobile)

I would like to take the stress out of my window switches by having the window motors controlled by relays rather that all the currant going through the switches I have looked in the archives in the hope that someone may have a schematic on how to wire this up to no avail as I am bit of a neo Luddite with wiring I need all the help I can get anybody.....???

My next question relates to the heater switch, I have the oblong three position switch (off, on , on) but the space/rebate for it behind the dash only allows for the single on, off switch so is my dash wrong or do I have the wrong switch? ( this switch is the same as my light switch) anyone able to let me know the correct switch part number? My heater fan is defiantly two speed

I am also looking for an alternative wiper switch which will also operate a washer motor (electric) I do not have the knob from the original switch so the offering from the Elan Factory is probably no good unless I can find a knob somewhere any suggestions for an alternative switch with a suitable knob? not that fussed about originality as long as it looks reasonably period.

Thanks in anticipation.

Tonyw
'68 S4 DHC
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PostPost by: billwill » Fri May 13, 2011 1:57 pm

For those of us who prefer diagrams to descriptions, this is the circuit that Colin describes.

It is better than my draft circuit above because it uses cheaper single pole changeover relays and does not short-circuit if both relays are closed at the same time.

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PostPost by: Tonyw » Fri May 13, 2011 3:13 pm

Thanks for the replies,

I now have a good solution to the window motor wiring I shall pick up some relays over the weekend.

Tonyw
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PostPost by: billwill » Sat Apr 13, 2013 3:33 pm

See also the discussion in the following thread.
electrical-instruments-f38/wiring-circuit-for-relays-the-window-motor-layout-t27854.html#p186815
especially in respect of relays with built in protective diodes.
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