Putting the Shadow back together (see Shadow 1 no ignition posting) and have come across a mystery wire on the alternator cable bundle. According to the wiring diagram the only white/brown plastic sheathed wire goes to the oil pressure switch, but it does not seem long enough. Any ideas what it plugs onto?
And before you ask, I did not even notice this had become disconnected - everything else has gone back where it should.
Silver Shadow Mystery Wire
Silver Shadow Mystery Wire
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Re: Silver Shadow Mystery Wire
According to the list of UK wiring colour codes that we work from, brown/white trace is the feed from the alternator's voltage regulator to the ammeter. Is the ammeter not working? It could be difficult to tell if the battery is already fairly well charged and you're not taking much current when checking.
That end must go to the regulator as it's not long enough to reach the dashboard.
On the Rolls Royce/Bentley wiring diagram, as with all standard UK ones, brown is N, not B, hence the code by that regulator/ammeter wiring in the diagram saying N/W = brown, white trace.
That end must go to the regulator as it's not long enough to reach the dashboard.
On the Rolls Royce/Bentley wiring diagram, as with all standard UK ones, brown is N, not B, hence the code by that regulator/ammeter wiring in the diagram saying N/W = brown, white trace.
J
"Home is where you park it", so the saying goes. That may yet come true..
"Home is where you park it", so the saying goes. That may yet come true..
Re: Silver Shadow Mystery Wire
Thanks very much. I had a good look at the alternator but could not see any appropriate lugs, but might have missed it. Will check again.
Much appreciated.
Much appreciated.
Re: Silver Shadow Mystery Wire
Put her back together and she started up first time.
Left that lead disconnected - the ammeter on the dash is registering charging, so now not at all sure.
Cannot see any lugs on the alternator and the regulator is too far away.
Left that lead disconnected - the ammeter on the dash is registering charging, so now not at all sure.
Cannot see any lugs on the alternator and the regulator is too far away.
Re: Silver Shadow Mystery Wire
For the ammeter to show a reading with that cable disconnected from the regulator, the shunt must have become disconnected which means that it could be possible for full charging current to pass through the ammeter - on these it works by showing a reduced current, based on the R value of that shunt.
Here's the diagram for the area you're looking in to replant the cable:
Here's the diagram for the area you're looking in to replant the cable:
J
"Home is where you park it", so the saying goes. That may yet come true..
"Home is where you park it", so the saying goes. That may yet come true..
Re: Silver Shadow Mystery Wire
Thanks.
Just to check - the regulator is on drivers side bulkhead adjacent to the windscreen washer bottle?
Just to check - the regulator is on drivers side bulkhead adjacent to the windscreen washer bottle?
Re: Silver Shadow Mystery Wire
curiouser and curioser..
Generator light on the dash is behaving normally - on at idle, but off when the throttle is blipped.
ammeter is doing what it has been doing since I restarted the car some months ago, during which time battery has been charging OK.
Looking at the circuit diagram, most of the wires in the area that you highlight are cotton covered -'C', but this has a black plastic sheath over the top.
Also does the order of the colour code letters signify the dominant colour - my cable is white with a thin brown stripe, so should be 'WN' not 'NW'?
Generator light on the dash is behaving normally - on at idle, but off when the throttle is blipped.
ammeter is doing what it has been doing since I restarted the car some months ago, during which time battery has been charging OK.
Looking at the circuit diagram, most of the wires in the area that you highlight are cotton covered -'C', but this has a black plastic sheath over the top.
Also does the order of the colour code letters signify the dominant colour - my cable is white with a thin brown stripe, so should be 'WN' not 'NW'?
Re: Silver Shadow Mystery Wire
OK, the diagrams in the manual give a "theoretical" and a "likely" version of each part of the wiring loom, presumably the brief way to allow for year on year changes to some things. That the ignition lamp and the ammeter appear to operate as they did before suggests that nothing is wrong and yes, the first colour is the base, the second the trace so you'd be correct to assume that this cable would - by that logic - have been marked up as WN.
The fact that some are cotton covered in the diagram isn't something set in stone as that page is from one of the "theoretical" pages, so I'd hazard a guess that this varied through the years (that copy of the manual was published in 1971).
Your alternator is clearly an AC type but could the car you have be from a year when ACR types were being introduced, in which case could it have been kitted out with a later wiring loom to take into account the later, battery sensing ACR alternator? That would explain why it all works without that connection being made yet, at the same time, I'd be surprised to find that Rolls Royce-Bentley had done such a thing on a car whose manufacturing process was so heavily dependent upon the manual input of one individual to each process, in which case it would have been simple for that individual to adapt the loom as they went without leaving loose things in about!
Have a close look at the mystery terminal on that cable; is that showing signs of having been connected to something recently? (bright edges where the spade has been slid along its male counterpart) or is that female equally tarnished over its surface in a way that suggests it hasn't been used?
It's great that everything works, but it's presumably frustrating for you to have found a connection that doesn't go anywhere and I'm thinking that it must have a home. Somewhere.
The fact that some are cotton covered in the diagram isn't something set in stone as that page is from one of the "theoretical" pages, so I'd hazard a guess that this varied through the years (that copy of the manual was published in 1971).
Your alternator is clearly an AC type but could the car you have be from a year when ACR types were being introduced, in which case could it have been kitted out with a later wiring loom to take into account the later, battery sensing ACR alternator? That would explain why it all works without that connection being made yet, at the same time, I'd be surprised to find that Rolls Royce-Bentley had done such a thing on a car whose manufacturing process was so heavily dependent upon the manual input of one individual to each process, in which case it would have been simple for that individual to adapt the loom as they went without leaving loose things in about!
Have a close look at the mystery terminal on that cable; is that showing signs of having been connected to something recently? (bright edges where the spade has been slid along its male counterpart) or is that female equally tarnished over its surface in a way that suggests it hasn't been used?
It's great that everything works, but it's presumably frustrating for you to have found a connection that doesn't go anywhere and I'm thinking that it must have a home. Somewhere.
J
"Home is where you park it", so the saying goes. That may yet come true..
"Home is where you park it", so the saying goes. That may yet come true..
Re: Silver Shadow Mystery Wire
thanks very much for this.
Hit another snag - car fired up perfectly after I put everything back together, but when I turned her over the next day there was an almighty crunch. Had the Carbs etc back off and both pushrods on the hydraulic pumps have bent - looks like the pumps locked and the weakest component gave first. Looks like 1 pump is toast, the other seems to be OK.
Now going through the power hydraulic system - accumulators and valves are off, to be cleaned up. Will come back to the mystery cable after everything is back together, but will probably just properly isolate it.
Hit another snag - car fired up perfectly after I put everything back together, but when I turned her over the next day there was an almighty crunch. Had the Carbs etc back off and both pushrods on the hydraulic pumps have bent - looks like the pumps locked and the weakest component gave first. Looks like 1 pump is toast, the other seems to be OK.
Now going through the power hydraulic system - accumulators and valves are off, to be cleaned up. Will come back to the mystery cable after everything is back together, but will probably just properly isolate it.