Headlights earthing problem????

Alfieslandy · Oct 28, 2020

Defender problem number 336.... or so it feels The symptoms are as follows

engine running

headlights or sidelights on

turn engine off and it continues to run

intermittent and does not occur when lights off

Im thinking earth problem please tell me i am on the right track?

Alfieslandy · Oct 28, 2020

Oh and the battery warning light flickers dimmly during said problem...

raisingveg · Oct 28, 2020

my money is on a grubby earth somewhere

mick 1986 · Oct 28, 2020

Alfieslandy said:
Defender problem number 336.... or so it feels The symptoms are as follows

engine running

headlights or sidelights on

turn engine off and it continues to run

intermittent and does not occur when lights off

Im thinking earth problem please tell me i am on the right track?

Not sure what defender, 90, or 110, you drive but on mine (1992 200TDi) my headlights earth onto the galvanised steel front inner arches. To get round issues like this, I extended these earths back to the main bulkhead earth, and then extended that back directly to the main battery earth. As a starting point, I would investigate the front inner arches and run a piece of temporary wire from the battery neg to the earth point. Also investigate the engine and chassis earth, look under the passenger seat for the main earth. It should go onto a gearbox mount, then up to the transfer box.

Here’s what I installed on mine.

This is the earth stud they both come back to, and this is extended back to the main battery earth.

wireman · Oct 28, 2020

If you have a diesel engine and it continues to run when turned off it sounds like an issue with your stop solenoid. If it only happens when the lights are on it could be that the lights are powering the solenoid somehow ?!? As others have said, check all of your earths first, but check your stop solenoid as well while you're under there.

mick 1986 · Oct 28, 2020

wireman said:
If you have a diesel engine and it continues to run when turned off it sounds like an issue with your stop solenoid. If it only happens when the lights are on it could be that the lights are powering the solenoid somehow ?!? As others have said, check all of your earths first, but check your stop solenoid as well while you're under there.

I did think that at first, but he says that it doesn’t do it when the lights are off. I would guess the, stop solenoid circuit is fine in that respect, and the fault lies on the headlight (or earth) circuits.

wireman · Oct 28, 2020

mick 1986 said:
I did think that at first, but he says that it doesn’t do it when the lights are off. I would guess the, stop solenoid circuit is fine in that respect, and the fault lies on the headlight (or earth) circuits.

Weird electrical issues are usually bad earths, off the top of my head I have no idea how having the lights on affect the engine running, but then you never know what 'modifications' (bodges) previous well meaning (lazy) owners have done.

Colthebrummie · Oct 28, 2020

Bad earths usually result in no power. My guess is there is a short from a live feed somewhere. If you have a circuit diagram, check the ignition circuit, it must be picking up a live feed from the light circuit somewhere.

Col

Alfieslandy · Oct 28, 2020

Hopefully it is something as simple as a bad earth. Rebuilt onto a new chassis last year and i did take note that the earth negative battery lead is not in great shape. It runs battery > flag lug to chassis > gearbox. The crimp on the chassis cable is loose to a degree. I rebuilt it with a replacement bulkhead from a 300tdi and associated wiring ( it is running a 300tdi engine ) which i repaired and painted using 2 good coats of 2k epoxy primer. I think the earths for the lights terminate on a central stud on the bulkhead leaving me now wondering that the earth route from this to chassis is not all that great.just ordered new genuine negative battery lead ( ouch that was dearer than expected ) and a length of suitable wire to strap the bulkhead to chassis. Hopefully i am on the right path. Just nipped out to check it again and its not doing it at this moment. At work though so no further time to investigate

tottot · Oct 28, 2020

Any extra earths are a good thing on a landy.
It may be worth a look at the condition of the dip switch and the back of the ignition switch for any sign of shorting.

Alfieslandy · Oct 28, 2020

tottot said:
Any extra earths are a good thing on a landy.
It may be worth a look at the condition of the dip switch and the back of the ignition switch for any sign of shorting.

Good call i had not thought about that

Alfieslandy · Oct 30, 2020

Well might be getting somewhere. Fitted new battery negative earlier and the stud it terminated on the box was quite oxidised and generally not good so cleaned that up before fitting. I’m not sure if I have cured the original problem as I say it’s intermittent but I have now got 3 different speeds for the first time on my wiper!! Previously I only had intermittent , slow and erm slow instead of fast! Turned the engine on and off a good few times with the lights on and no fault as of yet.

Alfieslandy · Dec 7, 2020

Quick update for those interested. Problem did reapear and was caused by faulty stop tail bulb holder!

tottot · Dec 7, 2020

Good update, old landy electrics!

Headlights earthing problem????

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