The Lotus Grand Tourers

Posted: **Mon Aug 04, 2025 11:48**

Ok time to admit to a little stupidity that appears to have resulted in a number of electrical problems.

This all relates to a 1978 éclat 520

First the problems -
1) no ignition warning lamp showing with ignition on
2) alternator doesn’t appear to be charging as only 11v at battery with engine running. 12.5v engine off.
3) indicators - fronts on solid and no rears
4) hazards - fronts flash very very fast and no rears

I’ve not long had the car and currently recommissioning it after 4 years off the road.
When initially tested the indicators and hazards were definitely working. Not 100% sure about the alternator, but didn’t notice any charging issues, but also didn’t check at the time.

Now the confession of stupidity
I had removed the steering rack and one of the bolts being what the main earth strap from the engine to the chassis is connected to.
Now the stupid bit - I cranked and started the engine with this earth strap still disconnected

The above issues were noted after this.

So what have I likely broken??

I hate electrickery - you can’t see it !

I’ve been trying to research things and I’ve found that the ignition warning bulb illuminating acts to excite the alternator to get it charging, so that will need investigating - hopefully just a bulb.

Would the low voltage with alternator not charging cause flasher units to not work correctly?
Why just front indicators and no rears. I’ve checked earth to rears and appears all good.
So what else could I have broken - alternator?

The car is 120miles away, so wanting to make a test plan and take basic stuff to try to sort, so what bulb does ignition warning light use ?
Any advice on testing to track down issue?
Anyone know somewhere around Leicestershire that can test an alternator

Thanks - I will now skulk into a corner and pray to the gods of mystical forces

Posted: **Mon Aug 04, 2025 13:00**

Alan_M wrote: Mon Aug 04, 2025 11:48 Ok time to admit to a little stupidity that appears to have resulted in a number of electrical problems.

This all relates to a 1978 éclat 520

First the problems -
1) no ignition warning lamp showing with ignition on
2) alternator doesn’t appear to be charging as only 11v at battery with engine running. 12.5v engine off.
3) indicators - fronts on solid and no rears
4) hazards - fronts flash very very fast and no rears

I’ve not long had the car and currently recommissioning it after 4 years off the road.
When initially tested the indicators and hazards were definitely working. Not 100% sure about the alternator, but didn’t notice any charging issues, but also didn’t check at the time.

Now the confession of stupidity
I had removed the steering rack and one of the bolts being what the main earth strap from the engine to the chassis is connected to.
Now the stupid bit - I cranked and started the engine with this earth strap still disconnected
The above issues were noted after this.

So what have I likely broken??

I hate electrickery - you can’t see it !

I’ve been trying to research things and I’ve found that the ignition warning bulb illuminating acts to excite the alternator to get it charging, so that will need investigating - hopefully just a bulb.

Would the low voltage with alternator not charging cause flasher units to not work correctly?
Why just front indicators and no rears. I’ve checked earth to rears and appears all good.
So what else could I have broken - alternator?

The car is 120miles away, so wanting to make a test plan and take basic stuff to try to sort, so what bulb does ignition warning light use ?
Any advice on testing to track down issue?
Anyone know somewhere around Leicestershire that can test an alternator

Thanks - I will now skulk into a corner and pray to the gods of mystical forces

If you can see (just follow tthe smoke) the electrickery you really have a problem.

Indicators: check that the rear bulbs are good and making proper connection. The turn signal relay needs the proper load to function. Next pull the relay and check it doesn't look melted. If it doesn't and still doesn't work open up the housing and check that the contacts aren't corroded/welded shut etc and that the heating wire is still there

Alternator: ground the SMALL wire (61) and see if the ignition light comes on. If it does, i would check the brushes in the alternator

Posted: **Mon Aug 04, 2025 18:23**

Do you have the circuit diagram Alan? I can scan and email to you if not.
I don't think your action of starting with the main earth strap disconnected caused or broke anything. If there was a good enough earth for the starter motor (via other routes), then I can't see any electrical component getting toasted.
For lights, there's a fuse for LH side and separate one for RH side, but indicators are all on same circuit. 12V feed for front and rear splits rights before the bulb, so I'd suspect you're still getting 12v to the bulb, but no earth. As Marten said, once one corner stops working, the hazard flasher will go faster so I wouldn't worry about that. The earth's on the rear lights can be quite an issue as it relies on 'spring clips' into alloy back plate.

The charging issue may have been there all along, you just didn't realise until now.

Posted: **Mon Aug 04, 2025 19:43**

I do have a copy of the service notes with wiring diagrams, thanks.

It is possible the charging issue was there, but I’m sure I checked all the gauges were working and think I would have noticed if voltage had been so low.
But the indicators and hazards were working. So something changed.

I did check earths at rear lights and all seemed very good although there does appear to have been a previous issue as the right indicator bulb holder has an earth wire soldered directly onto it.

When I cranked it without the earth strap it turned very slow and I didn’t crank it once - took a few goes before it started.

My worry is what route did earth take if not through the main earth strap?

Posted: **Mon Aug 04, 2025 22:49**

I think that the alternator will have an exciter wire that's connected from the ignition via the charging light to turn the alternator on.

Possibly a brown/yellow wire from the red ignition light to a control box labelled Ignition W/LT Control (no idea where that would be) then from that on a brown slate wire to the alternator.

I took those wire colours from the elite/eclat wiring diagram.

Posted: **Tue Aug 05, 2025 13:00**

Cranking with no earth strap - the electricity's preferred route seems to be the throttle cable. The carbs have an earth strap to the inlet manifold, and thus the rest of the engine (or should do!), then the electricity runs up the throttle cable, into the pedal, into the pedal box, and I guess there must be something there that connects to the chassis but I'm not sure what.

I managed to melt my throttle cable a couple of weeks ago, I had replaced the earth strap to the engine but it was too filthy to allow much electricity to flow. Just like you, it took several very lethargic turns of the engine to get it to fire.

As for your electrical maladies. I guess it's possible the electricity also found a route to ground through the alternator and has fried that. My hunch is that the indicators/hazards is coincidence, but I'd start with fuses, then relays, then bulbs.

Posted: **Fri Aug 08, 2025 22:23**

A little update, some good and some not so.

First the good - replacing the bulb for the ignition light that was found to be blown has brought back the charging.

The not so good - I still have no rear indicators and also no reversing lights. Side, number plate and brake lights fully working.
I’ve checked the reverse light switch and there is 12v to the switch and 12v from the switch when in reverse, so that’s working.

I did fit a new indicator switch and whereas with the older one the front indicators were on solid, with the new one they do flash.

So, my current theory is there is a connector somewhere that has 3 poor connections. I’m guessing this may be somewhere under the dash or in the right side space behind the kick panel.

Now I’m back with the car I can see there is a fundamental difference between the éclat and the Elite and Excel. As the éclat has the battery under the bonnet it earths directly to the back of the engine using a bell housing to engine bolt. There is then an earth strap from the engine to chassis via the steering rack mount. So when I started it there was a good earth to the starter motor, but not to the rest of the electrical circuits.

So tomorrow I will be adopting the Lotus position to explore under the dash and in the footwell.

Posted: **Sat Aug 09, 2025 11:26**

There are two connectors that connect the front loom to the rear - driver's footwell - I'd start there.

Pete

Posted: **Mon Aug 11, 2025 21:07**

Just to round this off - there were a few issues sort of masking each other.
There had been some skull bodgery by a previous garage to the earthing system.
The original earth for the right cluster had been removed and left hanging disconnected. There were simple wrapped connections between several wires hiding under insulation tape (no solder in sight).
They had then attempted to solder an earth to the bulb holder that tested ok with the pressure of my testers probe, but was fairly poor when not pressed on.
Then there was corrosion between the earth ring of the bulb holder and the copper bulb earth contact. Again this tested ok with full pressure from my test probe, but very poor with just the bulb.
So correct earthing system reinstated. New bulb holders on order.

Almost ready for the road.

The Lotus Grand Tourers

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