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Discussion Starter · #1 ·
Hello everybody,

I need help about all the connections about the speedometer and odometer, please. Cause the daily mileage and the mileage don't work.
I removed the box of speedometer and some cables are completely disconnected from the dashboard (not from the box speedometer).
Do anyone have the right electrical diagrams for the speedometer between 1977 until 1980, please?
My car is a RR Silver Wraith ll of August 1979 LRH37466, Right hand.
11 owners before me. And I know for sure that the speedometer is not the original, cause on the MOT website, I read diferentes mileage, between the controls, to be more clear, the mileage today is downer than before. And the last owner told me, he changed the speedometer himself, cause the last one didn't work...

I know too, the speedometer for the last RR Silver Wraith ll for the America (1980's models), have a white cable to replace the red/green to alimentation of the mileage. It's my case (my car is from England, but the speedometer box seems be from America)...
Some pics to show you the piece...

Thank you in advance.
Have a nice day.
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As you have said, looks like the wiring colours changed for the American market as there is no "white cable" anywhere near the speedometer on my British market cars.

The wiring diagrams show that the "white cable" replaces the green wire not the red/green wire. The red/green goes to the speed generator and speed control.
The white wire comes from the petrol pump relay on American market cars, which in turn is fed by fuse 2 on the fuse board.

The wiring diagrams I am looking at were printed in May 1980.

If that is no help, look at early SZ model cars as the Spirits were a continuation of the Shadow 11.

Jake.
 

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Wiring colors do not change for a market. It would add a lot of confusion. RR generally codes their wiring and keeps colors consistent through the years.
 

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Wiring colors do not change for a market. It would add a lot of confusion. RR generally codes their wiring and keeps colors consistent through the years.
The above is not true. There are variations for different markets as you should know.
Wiring diagrams will often show a dotted line with the colour which means this is how some cars for different markets are wired.
The diagram I am quoting is in section M4 page 16, TSD 4200. Check it out as this shows the alternative wiring for the speedometer. Sorry but you will not be helping the OP when you put confusing information on the forum.

Jake.
 

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The primary and secondary circuit colors would be the same regardless. When there are added accessories or market/country mandated items such as lights, horns, etc, they are shown with a dotted line.
There is no intent to confuse anyone. Someone with an electrical background would know this.
 

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I did not think a speedometer is an added accessory, so as an automotive electrician I can safely say the speedometer wiring is different for different destination cars, like it or not.
There is no white wire anywhere near the speedometer on British cars and the OP was asking about the white cable that was connected to the speedometer on his vehicle.
The white wire replaces the green wire on some models.
Wraithman, if you cannot understand that, it might be you who do not understand wiring diagrams. Check it out.

Jake.
 

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His best bet is to work backwards. The speedos change depending on year and final destination. Use the Bentley site to figure out the speedo he should have from inception. If the number on the present one does not match, you may find your answer.
 

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Here's info about the dotted line. It's in Chapter M, page 15.
 

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The white wire shows it goes to the fuel pump relay.
 

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Discussion Starter · #12 ·
Thank you so much for your informations, Jake and Wraithman.
I found the same affirmations than Jake.
And I remember the white cable goes to the pumps relay. But I had some mistakes about the connection.
First, I tried on the W1 and after , on the W2 of the pumps relay :-( each time I broke the fuse 2...
I will try to connect tomorrow the white cable on C3 of the pumps relay to see if anything changes.
But do you think, I must connect the white cable with the green cable? I know for sure that the both were connected on the speedometer. But I don't remember if the white and green cables were separated or together...
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Sorry for the delay in replying.

The first mistake with the wiring as shown in your photos is you have got a white wire connected to the speedometer earth, terminal 31b, NO wire is connected to this terminal.

Only the "+" "2" "A" terminals are used nothing on the "31b" terminal

Looking at your photos, I would try and see if it works correctly leaving the white wires disconnected, make sure they are covered so they do not short and blow a fuse.

If the speedometer is still not working correctly, try putting the thinner of the white wires onto the "+" terminal, leaving the green wire off altogether.

The black and red/green wires are on the correct terminals.

I am not sure why you have two white wires behind the speedo but as others have been at the wiring, who knows.

Let us know how you get on.

Jake.
 

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Depending on chassis number, you will have 2 white wires as indicated in the workshop reference above. There is a specific reference to this for those who care to read it rather than assume it's existance. Workshop manuals are a great source of knowledge even to those who claim experience.
 

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Depending on chassis number, you will have 2 white wires as indicated in the workshop reference above. There is a specific reference to this for those who care to read it rather than assume it's existance. Workshop manuals are a great source of knowledge even to those who claim experience.
While I will not dispute this, my wiring diagrams only show one white wire which can take the place of the green wire.
There could well be later diagrams showing two whites.
If you can, it would be more helpful to tell the OP where the two white wires connect to, rather than keep trying to criticise my suggestions.

Jake.
 

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Again, depending on chassis number, there is a #14G green and a #9white (thin) attach to speedo. This white wire now travels to the relay at terminal C3 to be joined by another white wire. Clear as day on the wiring schematic.
Jake, nothing is directed at you. If this is a new marque for you it is quite different with a long a steep learning curve and lucky for you there are members here with long relationships with their car and can give you and others, straight answers.
 

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Again, depending on chassis number, there is a #14G green and a #9white (thin) attach to speedo. This white wire now travels to the relay at terminal C3 to be joined by another white wire. Clear as day on the wiring schematic.
Jake, nothing is directed at you. If this is a new marque for you it is quite different with a long a steep learning curve and lucky for you there are members here with long relationships with their car and can give you and others, straight answers.
So, yes there are two white wires but as you have said they come together at the relay not the speedometer. Like I said, only one white goes to the speedometer on some models.

I have been a custodian of a Shadow 11 for many years now and while I do not profess to know everything about them, I had to restore it and the electrical system was in a complete mess. The only things that worked were some of the lights, gearbox actuator, starter and ignition system.
When you have to completely overhaul and repair the A/C, heater wiring system the rest of the electrics on a Shadow is very easy and straightforward.
I understand Shadow 11s and I, unlike some, only ever post on what I know, Shadow 11s.

Jake.
 

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Same here Jake, only SY cars for me. I have a few vids on Youtube under my s/n
 

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Discussion Starter · #19 ·
Thank you Jake and Wraithman,

Wraithman you are describing exactly the connections I thought have before. A bridge with this White wire from the speedo, with another wire who goes to the C3 of the pumps relay... But do you thing the White wire from the speedometer was connected from the (+)...?
I have just one Green wire connected to the (+) of the speedometer, not two...

Today, I have just leave completely the White wire (like Jake, Introcar, and Rodd Sala asked me to do). I have to test the car on the road to see if something change. But I wouldn't do it before next thursday.

Today, I tried to connect the White wire from the 31b to the C3 of the pumps relay. Of course, the fuse number 2 broke...

I have all ready test the White wire connected from the (+) with the green wire, to the 31b... This time was the fuse 1 who broke.

I think, I will test the White wire connected with the Green wire, to the (+) of the speedo, and connect the White wire to the C3 of the pumps relay, this week ...

I post for you, pictures of the pumps relay taked before all my problems, but sorry this difficult to see very clear the connections...
(I specify that the original white cables which burned out have since been replaced, it was after having wanted to remove all the blue caps from the bulbs which prevented me from seeing how fast I was driving at night ... The miles are visible because they are written in large on the speedometer but not the kilometers ... My Rolls was made for the English market).

Jake, I have only one White wire from the speedo, not two. It's true my picture could show there are two, but no...

Thanks a lot for your ideas ;-)
 

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