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Do you like or dislike the new dashboard ?
Yes I do like the new dashboard
100%
 100%  [ 7 ]
No I do not like the new dashboard
0%
 0%  [ 0 ]
Total Votes : 7

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ukdave2002



Joined: 23 Nov 2007
Posts: 4398
Location: South Cheshire

PostPosted: Thu Aug 13, 2026 10:27 am    Post subject: Reply with quote

does the connection from the sender to the warning lamp earth it or provide the -12v ( - as you have a +ve earth)
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Ray White



Joined: 02 Dec 2014
Posts: 7647
Location: Derby

PostPosted: Thu Aug 13, 2026 10:43 am    Post subject: Reply with quote

ukdave2002 wrote:
does the connection from the sender to the warning lamp earth it or provide the -12v ( - as you have a +ve earth)


The supply -12v goes to the sender and it is + earthed through the body of the sender.
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ukdave2002



Joined: 23 Nov 2007
Posts: 4398
Location: South Cheshire

PostPosted: Thu Aug 13, 2026 1:03 pm    Post subject: Reply with quote

Ray White wrote:
ukdave2002 wrote:
does the connection from the sender to the warning lamp earth it or provide the -12v ( - as you have a +ve earth)


The supply -12v goes to the sender and it is + earthed through the body of the sender.


So the bulb picks up the -12v from the sender (normally when the tank level is low) and the other side of the bulb is earthed in the dash. It's an odd design as it would be far simpler to pick up the earth from the sender, but who am I to question MG logic!
I recall you said the sender had a coil, if the coil has gone s/c it would explain why the lamp is on with a full tank but wouldn't explain why the lamps dim when the sender is in the low position.
It's odd, with the cover off, I'd take some voltage measurements at both ends of the coil with the sender in different positions, that should throw some light on the issue, also check the coil for a s/c.
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Ray White



Joined: 02 Dec 2014
Posts: 7647
Location: Derby

PostPosted: Thu Aug 13, 2026 1:30 pm    Post subject: Reply with quote



This is the wiring diagram that I have followed; if it helps.?

I can try to test for s/c but I am not really sure what to do.
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ukdave2002



Joined: 23 Nov 2007
Posts: 4398
Location: South Cheshire

PostPosted: Thu Aug 13, 2026 2:04 pm    Post subject: Reply with quote

Ahh, so there is no -12v to the sender, the sender simply grounds the bulb, this is far more logical Smile

Has any other part of the wiring been disturbed? I ask because the sender is a simple on off switch, it can really only have 2 faults it either goes open circuit in which case the lamp wont work at all or it goes short circuit so the lamp will be on all the time, but doesn't explain why the other bulbs dim when the tank is low?

Does the sender its self have a good earth, and with the warning lamp disconnected, the sender in the low fuel position is there a good earth on the "output" side of the sender? these could be checked very quickly with an ohmmeter.
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Ray White



Joined: 02 Dec 2014
Posts: 7647
Location: Derby

PostPosted: Thu Aug 13, 2026 3:03 pm    Post subject: Reply with quote

ukdave2002 wrote:
Ahh, so there is no -12v to the sender, the sender simply grounds the bulb, this is far more logical Smile

Has any other part of the wiring been disturbed? .


What has happened is the leaking petrol has saturated the wiring harness that runs directly under the tank.

The sender has a good earth.
I added a separate wire as a back up.

I will carry out the resistance test that you suggest.

.........Jean has persuaded me not to do it today because of all the extra heat and the risk with petrol fumes...
. Shocked
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ukdave2002



Joined: 23 Nov 2007
Posts: 4398
Location: South Cheshire

PostPosted: Thu Aug 13, 2026 3:46 pm    Post subject: Reply with quote

Ray White wrote:

I will carry out the resistance test that you suggest.

.........Jean has persuaded me not to do it today because of all the extra heat and the risk with petrol fumes...
. Shocked


A good call !! Smile

Ahead of an extension, I demolished our existing utility room this morning, and had to hand barrow the contents 100 yard to a skip this afternoon, wrong day to do it!

However the beer I am now having tastes good Smile

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Ray White



Joined: 02 Dec 2014
Posts: 7647
Location: Derby

PostPosted: Thu Aug 13, 2026 4:37 pm    Post subject: Reply with quote

Talking about working in this heat; we have been clearing out a property recently vacated by a tenant. I had a quote of 3K just to clear all the detritus she has left behind. That was too much so we have attempted it ourselves. So far we have made 12 trips to the tip with the old P38 filled to the roof.! We even had to demolish the kitchen!

We had to get a Court Order to evict the woman but she has left owing us 11K in back rent which we will never see.

Apart from totally redecorating I will have to fit a new kitchen and all new carpets and floor coverings before it can be put up for sale. Shocked

This tale of woe is basically because our letting agent went bust and destroyed all the paperwork. I could write a book!

.
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alastairq



Joined: 14 Oct 2016
Posts: 2236
Location: East Yorkshire

PostPosted: Thu Aug 13, 2026 5:51 pm    Post subject: Reply with quote

Touch wood [taps forehead]...i have been a good tenant to my landlord over the past 12 years.

But I did warn him, if he decides to put the rent up, then I probably won't be able to afford it, and will move out.

Which means, for him, he would have to renovate/decorate/new kitchen/bathroom, etc to the house for the next tenant [who will doubtless be short-term?]...costing many thousands of pounds...
Oil fired [hot water/central heating ] boiler will have to go for starters...seeing as we cannot get a lot of the spares for it any more.
I repair the log burning box repeatedly...As that would need replacing, as nobody is going to want to pay modern day rents [for the size of the house & land] for the basic amenities that I am more than happy with.

When, when the new tenant moves out, as they historically will do at the new levels of rent...the whole process..or most of it, will likely have to be gone through again?
So he leaves things as they are....Like most of the long term farmer landlords in this area do....I don't bother him either, unless there's a dire event occurring....

His wife is a local GP, so provides him with a 'social conscience' to boot.

He mortgages the house, and as long as the payments are more than met by my rent, he's happy.

Seems most of the village tenants renting from local estates or farmers, are elderly, and have lived in the same houses for...well...decades?

I get a bottle of wine left on my doorstep every Christmas, too.

Plus, I bought and paid for, a posh US made carport & had it put up alongside the house [we have a wide driveway]...That will stay.....So it's not as if I've been 'take all, gi' nowt' whilst I've been here.

My 'garage ' is a Dancover tent....now about to get its second heavy duty cover since I've had it.
The workshop at the top of the garden [two portacabins bolted together] has become highly rotten..I've had to 'ply sheet' most of the floor, as the vinyl lino which should have thick ply underneath, is very bouncy as the wood underneath has rotted away.

LL did nail a new metal roof on top of it, as the original was also rotted and leaked..Same with the concrete roof on the two outhouse sheds....

But I didn't complain...with the amount of garden I have available to use, I can plant my old wrecks, chassis, trailer, etc out of the way..without having to rent garages or the corners of fields.

So, all in all, consuming around half of my total pension income is maybe worthwhile for me....after all.
_________________
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Cannon special [1996 registered. Built in 1950's]
----------------------------------------------
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Ray White



Joined: 02 Dec 2014
Posts: 7647
Location: Derby

PostPosted: Sat Aug 15, 2026 4:00 pm    Post subject: Reply with quote

With the ignition switched on, I disconnected the top wire on the sender unit and to my surprise the light remained full on.

The light remained full on regardless of the float arm position... but this time there was no dimming of the other dashboard lights when put in the empty position; ie with the brass fingers making contact at the top.




ShockedAnyway. I think I have worked out where I have been going wrong. I have had to replace the warning light and amid all the frustration I have wired it up incorrectly.
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ukdave2002



Joined: 23 Nov 2007
Posts: 4398
Location: South Cheshire

PostPosted: Sat Aug 15, 2026 6:18 pm    Post subject: Reply with quote

Ray, all the sender does is provide an an earth to the warning lamp. If you have disconnected the sender, then, somehow the bulb is getting an earth from the loom, you mentioned that it was soaked in petrol, most looms especially modern ones are fairly petrol resistant, but clearly the lamp is getting an earth some how?
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Ray White



Joined: 02 Dec 2014
Posts: 7647
Location: Derby

PostPosted: Sat Aug 15, 2026 8:01 pm    Post subject: Reply with quote

ukdave2002 wrote:
Ray, all the sender does is provide an an earth to the warning lamp. If you have disconnected the sender, then, somehow the bulb is getting an earth from the loom, you mentioned that it was soaked in petrol, most looms especially modern ones are fairly petrol resistant, but clearly the lamp is getting an earth some how?


Thank you Dave. You have de mystified the system for me. Now I realise the sender is acting like a switch simply to earth the dashboard light everything makes sense.

I had to replace the light and mistakenly wired it incorrectly.

I shall report back with progress.

.
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ukdave2002



Joined: 23 Nov 2007
Posts: 4398
Location: South Cheshire

PostPosted: Sun Aug 16, 2026 8:08 am    Post subject: Reply with quote

Ray White wrote:
I had to replace the light and mistakenly wired it incorrectly.

I shall report back with progress.

That's why I previously asked if any other part of the wiring had been disturbed, the symptoms didn't make sense otherwise, it's good that you have tracked it down Smile
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Ray White



Joined: 02 Dec 2014
Posts: 7647
Location: Derby

PostPosted: Sun Aug 16, 2026 6:33 pm    Post subject: Reply with quote

Progress seems illusive. I was simply tightening the sender wire with a 5/16" brass nut onto the bulb holder and the thread snapped off. This is a new light and it is now completely broken and useless.

I must emphasise that I was not being heavy handed. Far from it; however, the connection does however need to be reasonably tight.

This means I will have to get another light and go through the whole frustrating business of fitting it in the dashboard again.

The cost of replacing poor quality parts is getting ridiculous now. Shocked

In fact I am attempting to superglue the broken old one back together. I have nothing to loose.

.

.
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bjacko



Joined: 28 Oct 2013
Posts: 579
Location: Melbourne Australia

PostPosted: Mon Aug 17, 2026 5:23 am    Post subject: Broken Light Reply with quote

I hope you told the company you bought the light from about the weakness?
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