Lotus Elan

Dynamo tpo Alternator Conversion- Lotus Elan 1968 S3 DHC

PostPost by: nico » Mon May 15, 2006 12:21 pm

Hi all,
I have just swopped the alternator over on my car and fits ok- but I need some details as to how to amend the wiring to suit the removal from the control box or regulator as they call it. I have seen the post in the technical tips section - only relates to the fitting of alternator only.

Does any one have any information or details on how to wire up the wiring so that circuits work.

Thanks in advance

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PostPost by: Nick Godfrey » Mon May 15, 2006 6:41 pm


I will try to look up the wiring. I think that I worked it out from a later drawing. Incidentally, mine is a +2 but it should be the same.

I left the regular box in place, took out the inside of it and used the connectors that come out as junctions for the wiring.

It look good as you do not have a load of wires going nowhere and you can oly tell that it has been converted when you look for the dynamo! And it all works well which is a bonus also ! :D
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PostPost by: prloz » Tue May 16, 2006 8:56 am

Hi Nico,
Alternator installation details are in the workshop manual X036T0327Z.
Section M11 - page 64 - Alternator Installing.
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PostPost by: steve71 » Tue May 16, 2006 10:23 am

Hi Nico,

I have a document that explains how to connect up an alternator. It explains which wires need to be connected to where and which wires are no longer required. If you want to PM me your email address I will send it to you.

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PostPost by: c.d.s. » Tue May 16, 2006 6:58 pm

Hello Nico,

This is what I did with my S3 Coupe. I've coded the wiring colors via
the lucas system used in the manuals.

To clarify how you could go about doing this I will lay out the stock system I found in the S3 im working on.

Polarity is Negative Ground.

Wiring at the control box:

Terminal 'E' / B ground wire for
control box.
*This is a ground for control box. I found
additional 3 ground wires.
2 from the main loom, and 1 from the
terminal that went to the solenoid mount
bolt as a ground.

Terminal 'D' / NY 2 wires.
1 NY from
generator to
1 NY from
control box.
to IGN warning
* this is the generator warning circuit

Terminal 'F' / NG Field to control
box. (main feed)
* this is the main feed from the generator
to the control box.

Terminal 'A' / N Control box to
starter solenoid
* this connects at the same location that
the main battery wire that comes from the
back of the car goes to, i.e. battery feed.

Terminal 'AI' / NU 2 wires.
1 NU from
ignition switch to
to control box.
1 NU from
control box to
main lamp switch
* this is your feed for the main lighting

Generator wiring:

Terminal 'F' / NG field from
generator to
control box.
Terminal 'D' / NY generator
warning circuit.

Now onto the conversion...

The Alternator:

Most alternators come with 3 wires coming out the back, the basic functions of most alternators are as follows.

Indicator/Warning/Failure / lucas color NY

Sense/Voltage Sensor / lucas color NB

Output/Main Feed (sometimes a bolt on terminal) / lucas color N

Ground / lucas color B
*The is ground usually being handled through the mount which in turn is also grounded to the chassis with a braided cable. Please make sure that these grounds are in good order as many electrical mysteries occur with inadequate grounding.

Basic 'Out the door' method:

I used the starter solenoid on the firewall as a junction block as I like the
remote button to bump the motor when checking valve clearances.

You can reuse the stock wire if youd like but can you sleep at night knowing that your wiring changes color inside the loom! javascript:emoticon(':wink:')

Terminal 'E' / B additional grounding wires are terminated elsewhere to an appropriate ground.

Terminal 'D' / NY wires are spliced together at the control box area, and the wire at the generator end (generator Terminal 'D') now goes to the Indicator/Warning/Failure terminal of your alternator.

Terminal 'F ' / NG is spliced or connected with Terminal 'A' N wire
this will serve as your main battery feed. Make sure the wires are up
to the task if you are using a high output alternator. There are many resources on the intershnitzel for appropriate size wire to amperage output. You may also choose to fuse or place a circuit breaker for additonal protection.

Terminal 'A' / N See Terminal 'F' above

Terminal 'AI' / NU splice or connect wires at the control box area and
add extension wire to connect to the solenoid terminal. The same place your battery cable goes to. There usually is a 3/8" male lukar connector there that would be convenient for this connection.

Additional alternator wiring.

Sense/Voltage Sensor terminal on alternator.
I have seen some conversions on other make cars where the sensor is just connected to the alternator main output/feed.
I have added a NB colored wire from the alternator to the starter solenoid battery connection.

I have also added an additional fuse box on the engine bay near the
alternator as I am running a feed/power wire direct from the alternator
to the additional fuse box, this will feed series of relays for the headlights.

Please note that this is what worked for me, and your cars wiring may

Also please take some time out to understand functions of the generator, alternator, and the control box it becomes much simpler than hooking up wire 'A' to wire 'B' and hoping for the best!

Best regards and good luck

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