Dashboard New Loom Spare Wires 1970 +2S

[Breezehill]

Just finished rebuilding the new dashboard with a new loom.

Sorted the additional wires which were fitted for the federal market, the drivers door buzzer and the brake fail test switch both these one taped off in the loom as original.

However I now have two wires with no connection and no reference on the wiring diagram. One is all brown with a bullet connector the other is red and black with a Lucas connector? On the original I have these two wires but connected into the bullet connector so brown into bullet and red and black out.

So on the new loom should these two be connected?

[HCA]

Red/Black is usually to the servo and brake fail switches. Brown is usually live all the time. I would have thought then that the red/black would join a green wire that is fed from the ignition switch via the tacho.

However, it is a Lotus, so I stand corrected if another convention is used...

[Breezehill]

HCA, thanks for the response.

The brown wire with the bullet goes to the 1 contact on the Park switch which also has Brown/ White attached. The Brown/White traced back to the ignition switch.

[HCA]

OK, hold fire!

I just pulled a copy of the +2 wiring, but it has no date! Interesting that the diagram shows red/black to all the brake fail switches and fed from a green off the switched 12V on the tacho...

However, in the explanation box it has for Red/Black : "control box to ignition swith P1., and light switch feed' but this is not shown on the diagram!

Check what colour you have for your side lights as some cars used red/black for sidelights rather than red. If you have red/black to sidelights, then your brown wire makes sense.

Sorry I cannot be more definitive or check mine, but I have just used two colours throught on mine.

I will try and pull some more diagrams...

[HCA]

Google 'wiring diagram Lotus Elan +2' that will show several different threads on the subject of wiring with many comments that a high percentage of the factory were colour blind (not strictly true as the looms would have come in from Lucas or anaother that will be made to design. So blame the designers!)

Anyway, of all the wiring diagrams in these threads, very few use red/black. One or two show your brown/white wire - but it goes from ignition switch to light switch (in itself is against convention as brown/white is usually from the alternator...) Is your car dynamo, alternator or alternator conversion?

Can you trace where your red/black wire goes? If you know this, it is easy to find a home for it..

[Breezehill]

Back in the workshop later this morning so will trace back on both wires.
Thanks for you help so far, good to bounce ideas.

[HCA]

If it helps, here is a screenshot of the only diagram where I could see re/black wire being used.. you will see it connects all the brake fail sensors, fed from a green wire to the brake fail light and on to earth. This despite the summary box saying it is from the control box to the ignition switch

[Breezehill]

HCA,

Think I may have resolved the issue.

looking at the hazard flasher from the rear its yellow/black, Light Green/Green, Red/Black. Checking this back the red and black here connects to the red/black in question.

The brown goes back to No 1 on the Park light switch which on the same connection is the larger brown/white which for back to the ignition switch.

Looking at the diagram in my works Lotus Workshop Manual at the Plus 2S with Alternator and the RB340 it shows White/Black from the hazard flasher unit which is on mine red/black. This white/black does on the diagram go to the clock and indeed there is a white/black on the clock

Looking at the old loom which was for the RB340 with Ammeter which has this brown connecting to the red/black. The red/black goes to the same position on the hazard flasher as the new loom. The brown does end up back at the ignition though via the ammeter. So having drawn the wires old and new on A4 it does seem this red/black and Brown should be connected.

[Breezehill]

The image of the wiring diagram is great, do they do one of the +2S with alternator?

The car was originally dynamo with RB340 but then converted to alternator by just hoping and changing cables. Since I was replacing the dash loom I decided to replace it with the loom for the alternator variant and I'm also changing the engine bay loom so again took the opportunity to use the alternator variant in doing so removes the connections to the old RB340 control box.

Engine bay wiring removed today so tidy up tomorrow and start to feed new loom in. Main reason for this was just after I first restored her back in the early 80's I had a fire under the carbs when a banjo bolt became loose. The insurance at the time took it into Kelvedon Motors in Spalding where Pat Thomas sorted it. Pat at the time was limited to the amount of work he could do by the insurance company and so the wiring loom below the carbs was repaired and not replaced. That and of course 50 years of ageing had taken its toll with corroded and brittle wiring.

[HCA]

Glad you are winning! Did you manage to find out what the re/black wire is feeding?

No, that screenshot I sent you was the only one I manage to pull from the internet with easy to see colour coding. There is mention of various diagrams being produced by individuals, but could not find anything. All were poorly reproduced copies of the myriad of diagrams in the workshop manual..

[Breezehill]

HCA,

Looking at the wiring diagram in the workshop manual, wiring diagram for the Elan +2S rhd alternator diagram LSL 178. If you look at this diagram the hazard flasher unit has the three connections Y/B (yellow/black), GLG (green/light green), W/B (white/black) however on the old loom these three connections have a difference where the W/B (white/black) is the R/B (red/black) which is the wire I had initially spare behind the lower set of switches.

I've looked on a number of diagrams for the +2S but none show this red/black.

Just on the engine bay loom having removed the old loom and ancillaries it's now on to checking the various senders and micro switches, relays etc before connecting all back up. All will become clear once all the connections are in place and the battery connected so I can see what is or isn't working.

[HCA]

I give up on the variations of wire colours that Lotus employed. I think there must have been a good supply of ganja around Norfolk in the seventies...

Generally, hazards and indicators use a green based coulour...

However, I note on some Elan diagrams, the main feed to the B terminal is green. This is silly as green is a switched 12V and hazards should be available with ignition off. I just wonder if a previous owner changed this and used a red/black cable to connect to a brown (which is always live...) just a thought.

Here is a useful link for you. It is only a guide, but mostly holds water:

https://www.autoelectricsupplies.co.uk/ ... rder_2.pdf

[Breezehill]

HCA

Think you could be right on the ganja front

Many thanks for your help, I'll get the rest completed the Do some testing and see what does or doesn't work.

The PDF very useful not only here but also for a TVR which I have.

Thank you

[HCA]

TVR? Which model?

The few TVRs I have had used just the one colour for everything. Black! I loved electrical issues on them

Maybe towards the end, TVR listened to all the wailing and gnashing of teeth and used the colour convention...If they have, and for any other Britsh car you might have, get to know what the main colours cover and it all should slot into place!

[alan.barker]

M SERIES WIRING CIRCUITStvr_3000s_wiring_diagrams_rev_1.pdf

(451.68 KiB) Downloaded 401 times

I have two TVRs a 1976 3000M wiring is colour coded.
Also a 1978 3000S wiring is all black.
So it was not an evalution for TVRs.
Here's the PDF for a 3000S but you could use it on other "M" series or other cars. It's clear and easy to follow.
Alan