rev counter disturbance

[Safi]

Hi

I have a well sorted Elan s4se which I have owned for 10 years, but recently it has developed a strange fault.

The car runs beautifully and all the electrical items work as they should. However, when i use any of the ignition related electrical components i.e. indicators, wipers, brake lights, fan, they work, but send the rev counter crazy (going back and forth from the extremes).I stop using them and the rev counter operates normally, which it has done for many years after SWLC sorted it.

I am wondering whether there is an earth fault and these components are earthing through the rev counter? But why all 4? I already have the recommended extra earths installed. I have replaced the fuse box and fuses.

Please can anyone point me in the right direction towards sorting this very annoying problem?

Thanks
Jim

[john.p.clegg]

Jim
You're right and to prove it just fit a temporary earth (from the battery if need be ) to the instruments..

John

[Safi]

Thanks John

I'll do what you suggest. I might be able to identify the one that is not earthing correctly, but I'm not knowledgeable enough to understand why the fault occurs with all the electrical items that come off the ignition.

I'll see how it goes and thanks again.

Jim

[nigelrbfurness]

Check the thumbwheel nuts on the instrument clamps haven't vibrated loose. That's a veey common cause of those symptoms.

[Safi]

Thank you.
I have checked this previously but I will check again.

[oldelanman]

I'm not knowledgeable enough to understand why the fault occurs with all the electrical items that come off the ignition

The ignition switch itself could be the culprit with dirty contacts causing high resistance and consequent voltage drop at higher current loads. I had a similar issue where the indicators would stop flashing when brake lights or heater blower were used ... eventually traced it to the switch and replacing it has cured the problem.

[Safi]

thanks Roger

That is interesting. Is it possible to clean the contacts?

Jim

[Grizzly]

I'm not knowledgeable enough to understand why the fault occurs with all the electrical items that come off the ignition

The ignition switch itself could be the culprit with dirty contacts causing high resistance and consequent voltage drop at higher current loads. I had a similar issue where the indicators would stop flashing when brake lights or heater blower were used ... eventually traced it to the switch and replacing it has cured the problem.

Ignition switch 01.jpg

Thats really interesting!!! I have the same issue as Safi that's been driving me mad since our car went back together, i plan to revisit it over the winter but the ignition switch would make sense. I also have another odd fault where the indicator tell tail only flashes once even though the indicators work correctly (might explain that too)

I have tried all sorts to fix my rev counter ( spiyda kit, fresh grounds, ground soldered direct to the spiyda board, new flasher relay, made sure all the bulbs are the correct wattage etc) i did check the ignition switch but not under load.

thanks Roger

[oldelanman]

If you can get the switch apart you could certainly clean up the contacts but if the switch is the original Lucas item, the body is ceramic and very brittle .... mine cracked when bending up the crimps that hold the two halves together so was not reusable ... you may have better luck. You could also try squirting contact cleaner into the switch, that improved mine a bit but didn't completely cure my problem.

[Grizzly]

Rodger, i'm going to cheat a bit i think and just replace the ignition switch with a new one for what they cost.

Am i correct in saying the S4 should be fitted with the lucas SPB501 ?

[oldelanman]

Rodger, i'm going to cheat a bit i think and just replace the ignition switch with a new one for what they cost.

Am i correct in saying the S4 should be fitted with the lucas SPB501 ?

Hi Chris,
Yes that's what I fitted. You probably have your own sources but I got mine from here .... https://www.ebay.co.uk/itm/231806223359
Advertised as genuine Lucas and came in a Lucas box but the item itself was unbranded so who knows
You may need to address the threaded part with a file to fit the hole in the dash .. my original switch had two flats and the replacement had only one. No big deal and once fitted the switch works fine, the original lock barrel also fits and works OK.
Hope it solves your problem.

[john.p.clegg]

..or even..

https://www.ebay.co.uk/itm/LUCAS-SPB501 ... SwWxNYnFY~

John

[Safi]

Hi

I've got a new switch from Mattys and i've got the old one out, but i'm not sure how you go about removing and refitting the old barrel to the new switch.

Can anyone advise please?

Thanks

Jim

[Safi]

Ah I see. you just depress the spring through the small hole in the body of the switch.

The inside of the old switch was a terrible mess. How it still managed to operate beats me. So i will fit the new one tomorrow with optimism.

I will post the results for others.

Thanks for all your posts and i do hope that this will be the end of this particular problem.

Jim

[weddingcarclive]

you put the ignition key in the switch in a certain position (can't remember whether position one or two then through the hole in the side of the switch assembly poke a nail or other instrument into the hole which will then release the the barrel to then pull out with the key