mike5ive said:
OK will do, thanks. I should also like to ad that its acts as a ground when tested with my multimeter / red to any power wire and black to it
That sounds a little confusing. Do you mean that you are using it as a ground wire when checking battery positive wire voltage? Or is it some other meter setting, etc?
A better check of whether it is a ground wire is completely disconnect your controller from everything, so all it's wires are unplugged.
Set your meter to 20ohms, or continuity if it has that.
Place your meter black lead on the controller's battery negative wire.
Place your meter red lead on this wire.
Note down the exact screen reading.
A reading of zero or less than 10 or so means that this wire is effectively connected to battery negative.
A reading above that may indicate it goes thru some other component inside first, and would require opening it up to trace out what the actual circuit is, and draw that out on paper.
You can also use the idea of that check to see if it is directly connected to something else, if it isn't a ground wire.
Completely disconnect your controller from everything, so all it's wires are unplugged.
Set your meter to 20ohms, or continuity if it has that.
Place your meter black lead on this wire.
Place your meter red lead on the other wire you wish to check connection with.
Note down the exact screen reading.
A reading of zero or less than 10 or so means that this wire is effectively connected to that other wire directly.
A reading above that probably means it isn't directly connected to that wire.
Move the red lead to the next wire you wish to check connection with.
Repeat steps above, until you find any connection, or all of them if there is more than one.
Do NOT do this test with any controller wire connected to anything other than the meter, or you may destroy the meter and potentially the controller itself or the other thing it's connected to, depending on what that is (like a battery). (It may just change the readings you get, if it's not a battery.)
To do this test connected to the battery, you'd need to be in 200 DC Volts mode on the meter first, but otherwise the steps are the same, but the way to read the results is different, so the best thing if doing this test is to post the actual test steps you performed, which wire was tested, and exactly what the reading and results were.
FWIW, it's a lot faster to find out by opening up the controller (but there is always the risk it won't go back together as easily, and/or won't work afterward).