Morris Minor Owners Club

Hi,
How does the later combined sidelight indicator earth out?
I can't see a wire apart from the 2 which go to each bulb so I assume it earth's out throught the body.
Thanks.

Exactly so. The base is metal, so should earth when screwed to the metal wing. They were never fitted with a seperate earth from the factory but if you feel you need one....it can be added of course.

ManyMinors wrote: ↑Mon May 06, 2024 7:06 pm Exactly so. The base is metal, so should earth when screwed to the metal wing. They were never fitted with a seperate earth from the factory but if you feel you need one....it can be added of course.

That's interesting (never having seen one myself), the W/S manual diagrams for those latter cars still show separate earth cable connection with a 'B' on it, not a direct connection, with no cable colour.

Artist got carried away with the column of Bs... Note the High Beam Lamp, 30, is shown as earthing via casing, without a 'B' cable.

I would guess 'B' stands for Body e.g. as stated above, connection to 0V occurs when the lamp is screwed to the Body!

Dave H.

The wiring diagram Geoberni shows is not for the later lights being discussed though. It is for the earlier cars with the clear glass front lights and small red rear lights which operate as flashers using the Lucas DB10 cut-out unit shown in the diagram

ManyMinors wrote: ↑Mon May 06, 2024 10:59 pm The wiring diagram Geoberni shows is not for the later lights being discussed though. It is for the earlier cars with the clear glass front lights and small red rear lights which operate as flashers using the Lucas DB10 cut-out unit shown in the diagram

Indeed, that is so. But it hardly makes any difference if, as you say, the cars "were never fitted with a separate earth from the factory". I say this on the assumption that you mean all cars, not just the later models?

Jeezzze!
I only posted to highlight that, having no personal experience of post -63 cars, based on ManyMinors feedback, the diagrams are incorrect as they illustrate cable connection.
However......

daveejhitchins wrote: ↑Mon May 06, 2024 9:15 pm I would guess 'B' stands for Body e.g. as stated above, connection to 0V occurs when the lamp is screwed to the Body!

Dave H.

Guessing?
Clearly electrical diagrams are not your forte....

B is for BLACK, the wiring colour for Earth Cables.
The highlighted item 55 is the illustration for no cable connection!

ManyMinors wrote: ↑Mon May 06, 2024 10:59 pm The wiring diagram Geoberni shows is not for the later lights being discussed though. It is for the earlier cars with the clear glass front lights and small red rear lights which operate as flashers using the Lucas DB10 cut-out unit shown in the diagram

Well it's a good job one of us can tell the difference between the wiring diagrams.
My car, although a SII, was fitted with a DB10 system around 1999 by a PO, so I have an intimate knowledge of how it works and which diagram is which!!

The one I posted is for "Models with Separate Flashing Equipment" and in this regard is identical to the final diagram issued which is for the Positive Earth Alternator cars.

THIS is the one for 'Later Type Flashing Indicator Control', which it was at the time the diagram was added in 1961, until the 'Separate Flashing Equipment' replaced it in '63....

I've highlighted the DB10 Relay to make it a little easier to spot...

The 4 items indicated in the bottom corner, items 49, 50, 51 and 52 in this case, are respectively:
Snap Connectors
Terminal Block or Junction Box
Earth Connections made via cable
Earth Connection made via fixing bolts

myoldjalopy wrote: ↑Tue May 07, 2024 9:44 am

ManyMinors wrote: ↑Mon May 06, 2024 10:59 pm The wiring diagram Geoberni shows is not for the later lights being discussed though. It is for the earlier cars with the clear glass front lights and small red rear lights which operate as flashers using the Lucas DB10 cut-out unit shown in the diagram

Indeed, that is so. But it hardly makes any difference if, as you say, the cars "were never fitted with a separate earth from the factory". I say this on the assumption that you mean all cars, not just the later models?

Actually ManyMinors is incorrect on his statement, there is no DB10 relay on that first diagram I provided, no matter how much he stares at it, he's never going to find it....
I think he's confused the rectangular illustration of the Light switch with the DB10.....

All the later diagrams in the Manual illustrate cable earth connection.
Early diagrams show a mix of cable connection and casing connection at different times.
I think after all these decades, your car has what it has, especially if it is pre -63.....

Them fiberglass wings don't earth very well no matter how many screws hold the light on

geoberni wrote: ↑Tue May 07, 2024 9:47 am

daveejhitchins wrote: ↑Mon May 06, 2024 9:15 pm I would guess 'B' stands for Body e.g. as stated above, connection to 0V occurs when the lamp is screwed to the Body!

Dave H.

Guessing?
Clearly electrical diagrams are not your forte....

B is for BLACK, the wiring colour for Earth Cables.
The highlighted item 55 is the illustration for no cable connection!
DB10 Diagram.JPG

50 years in electronics - retired Senior Engineer - I did mean to edit that post, within seconds - but was distracted by Mrs H, and forgot and it was getting late after a very busy day. But no harm done

Dave H.

daveejhitchins wrote: ↑Wed May 08, 2024 8:32 am

50 years in electronics - retired Senior Engineer - I did mean to edit that post, within seconds - but was distracted by Mrs H, and forgot and it was getting late after a very busy day. But no harm done

Dave H.

These things happen.
I find silly mistakes are more often made in the evening....

I was 37 years in aircraft electrics/avionics and the oldest wiring diagrams I ever worked with was in the mid 90s; they were American and from the early 1940s. Some of the symbology used on them took some getting used to.
Understanding Morris diagrams is a cinch by comparison.

Bill_qaz wrote: ↑Tue May 07, 2024 6:39 pm Them fiberglass wings don't earth very well no matter how many screws hold the light on

Some people just glaze over when trying to understand how the whole metal body shell is the earth return path to the electrical system.

Once had one of the technicians ask me to look at why every time he tried to connect the earthwire for the roof beacon to the cab frame it sparked. I switched it off then attached the wire, i gave up trying to explain its 24v positive until its fully grounded