Lotus Elan

What did you do to your Lotus today...

PostPost by: persiflage » Tue Apr 28, 2020 8:08 am

Chasing ghosts !
I spent the afternoon attempting to find the cause of the power feed (brown/blue) from behind dash to ignition switch becoming warm to the touch. Voltage drop from battery to switch is slightly high, most of it dropped between the bulkhead and switch .... This is going to be fun. While investigating I found the brown wire at the ignition switch had 12v on the end when it should be taking it from the switch connection :? All VERY Elan.
After some time investigating I traced the cause of the unwanted 12v was a back feed due to the disconnected courtesy light switches. You're never bored with Elan wiring ..... Confused, frustrated but not bored.
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PostPost by: HCA » Tue Apr 28, 2020 9:01 am

The brown wire at the ignition switch is always live and unswitched - it should show 12V all the time. Or am I not understanding correctly?

There are two brown wires, unswitched and live from the main solenoid - one to ign switch pos1 that is used to switch on pos2 a brown/blue and a red/blue wire to fuse various switched items. The other brown wire goes directly to a fuse that feeds the courtesy lights etc, so this wire should show 12V all the time whether or not courtesy lights are disconnected.

Do you have a car where a PO has dived into the wiring head-first maybe :evil:
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PostPost by: persiflage » Tue Apr 28, 2020 10:37 am

Brown / Blue feeds permanent supply to the ignition switch position 1. The Brown piggy backs off of that same (unswitched) position 1 to supply power to the window switches.. The way the harness is constructed with supply for one item piggy backing off supplies for totally different services can cause issues if there are resistance issues or disconnects.
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PostPost by: HCA » Tue Apr 28, 2020 11:48 am

Seems I have much to learn on Elans! I just googled their wiring diagrams and immediately came up with four different versions - two of them titled 'Lotus Elan Plus2' and very different from each other!

The old British convention in wiring is brown from solenoid to ign switch then with a different colour off to the light switch. A seperate brown wire came off the solenoid to a fuse box. Brown/blue and red/blue was from ign swith pos2 to the fuses for switched items.

I see one of the Plus2 diagrams followed this to a tee. But all the diagrams did show brown as the main 'always live' colour solenoid to ign switch and solenoid to alternator. I think it a bit naughty of Lotus to introduce brown/blue into this part as it would have confused mechanics who have it inbuilt where they see a brown wire, it is an unfused live and not to be messed with :)

A good reason then that I ripped mine out and putting in a more logical one :D
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PostPost by: billwill » Tue Apr 28, 2020 4:46 pm

Isn't any BROWN main colour always live, irrespective of the thin tracer colour?

See: https://www.autosparks.co.uk/bscc

It looks like Lotus were more correct than your data.
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PostPost by: HCA » Tue Apr 28, 2020 6:28 pm

Yes - solid brown is always live and brown/tracer is switched live.
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PostPost by: mbell » Wed Apr 29, 2020 3:05 am

Made a new crank case breather pipe, 11g lighter than the last one (more Ali pipe less rubber hose).

And up'd the rev limter from 6100 to 6400. When I was testing this weekend I was getting confused why it would hit the rev limter at upper 5k range but now I know why...
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: alan.barker » Wed Apr 29, 2020 8:12 am

persiflage wrote:Brown / Blue feeds permanent supply to the ignition switch position 1. The Brown piggy backs off of that same (unswitched) position 1 to supply power to the window switches.. The way the harness is constructed with supply for one item piggy backing off supplies for totally different services can cause issues if there are resistance issues or disconnects.

On my 1972 Elan Sprint you can lower windows with Ignition OFF BUT to raise Windows the Ignition needs to be ON :wink: :wink:
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PostPost by: HCA » Wed Apr 29, 2020 10:27 am

Funny you mention this Alan - not twenty minutes ago, amusing myself trawling through the different wiring, I saw this config on an undated +2 diagram with now indication what year or chassis numbers this applied to.

I can see no earthly reason why one would want a raw (brown to white/black)) supply to one operation and a switched (brown/blue to green) supply to the other.

Talking to someone t'other day, I mentioned I had left the MGB world and taken up the Lotus badge. He immediately replied '... loads of fun, they are the ultimate kit car!...' And he was serious :D :D

Screenshot 2020-04-29 at 11.18.41.png and
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PostPost by: alan.barker » Wed Apr 29, 2020 10:38 am

Maybe you can open the Windows with Ignition OFF as a safety feature in an accident (if the rest of the car hasn't exploded in bits everywhere :shock: :shock: )
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PostPost by: ericbushby » Wed Apr 29, 2020 10:44 am

Perhaps it is so that someone, maybe a child, left in the car could open the window if they were too hot , but could not reclose it thereby trapping a head, hand, dog etc. My S3 is not so sophisticated.
Modern car windows stop and back off if obstructed for that reason.
Just a thought.
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PostPost by: billwill » Wed Apr 29, 2020 12:31 pm

alan.barker wrote:
persiflage wrote:Brown / Blue feeds permanent supply to the ignition switch position 1. The Brown piggy backs off of that same (unswitched) position 1 to supply power to the window switches.. The way the harness is constructed with supply for one item piggy backing off supplies for totally different services can cause issues if there are resistance issues or disconnects.

On my 1972 Elan Sprint you can lower windows with Ignition OFF BUT to raise Windows the Ignition needs to be ON :wink: :wink:
Alan



That's a published safety requirement, to prevent children from getting their fingers caught (broken, chopped off) by a closing window when the children are unsupervised.
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PostPost by: persiflage » Wed Apr 29, 2020 8:04 pm

persiflage wrote:
Brown / Blue feeds permanent supply to the ignition switch position 1. The Brown piggy backs off of that same (unswitched) position 1 to supply power to the window switches.. The way the harness is constructed with supply for one item piggy backing off supplies for totally different services can cause issues if there are resistance issues or disconnects.

On my 1972 Elan Sprint you can lower windows with Ignition OFF BUT to raise Windows the Ignition needs to be ON :wink: :wink:
Alan

This is also a '72 Sprint ( originally Lagoon Blue also) which is the same as yours. Ignition must be on to lift the windows, the brown that piggy backs off the ignition switch supplies the down power. That supply is then piggy backed from the window switch as a red / white to supply the dashboard courtesy light.
Yes, the brown should be a permanently powered wire ..... Providing it is connected to the point that supplies the power :D . In this case the permanently powered contact of the ignition switch. With the brown (window supply) disconnected from the ignition switch 12v was being measured at the disconnected end. It should have been dead.
That 12v was the result of the permanently (brown) powered rear courtesy lights searching for an earth because I had disconnected both door plunger switches. That earth was achieved via the purple/ white from the rear courtesy lights to the courtesy light switch which then piggy backs to the other side of the dash courtesy light, through the filament and on to the disconnected end of the brown, earth finally being felt via the meter. No doubt if I had touched the the disconnected brown to earth, the dash light would have illuminated.
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PostPost by: alanr » Thu Apr 30, 2020 12:25 pm

Fed up with a flickering brake warning light I spent the morning refurbishing my Sovy valve. A good clean up of all of the bits and a cut down wine cork soon sorted it out.
Disassembled Sovy Valve..jpg and

refurbished Sovy Valve..jpg and


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PostPost by: nmauduit » Thu Apr 30, 2020 4:35 pm

alanr wrote:Fed up with a flickering brake warning light I spent the morning refurbishing my Sovy valve. A good clean up of all of the bits and a cut down wine cork soon sorted it out.


good job! I've been dreading that task to the point of getting used to the flickering... ;)

I note the nylon extension added to the regular Sovy : any reason for that? Also, your aluminium screw ring looks very good, did it come with the extra extension? on mine the locking screw ring is captive of the top, and weakened by corrosion, so I don't want to risk taking it out for fear that it won't seal when put back on...

_____________ edit

actually, enboldened by your post I had a go at an E-type Sovy I had around for spares (sitting for ages), and upon scrutiny I figured the rivet-looking fastners at the top would actually unscrew out under pressure (after all, they are of high pitch thread and into nylon) : gentle pry with a flat screwdriver, et voilà!

P1050529.JPG and
taking apart a Sovy top


thank you ! this is why I find the forum so invaluable...

---- re-edit (...)

I now fully realize the difference between a plus2 Sovy (your version, with the nylon extension) and the 2 seater Sovy (that goes into the tin can on Fed cars)... live and learn ;)
Last edited by nmauduit on Thu Apr 30, 2020 5:04 pm, edited 2 times in total.
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