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Old 23rd May 2020, 10:03   #7
COLVERT
This is my second home
 
R75 Saloon.

Join Date: Feb 2009
Location: France/or Devon.
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Quote:
Originally Posted by Andy24601 View Post
So I'e checked the continuity of the fuses under the bonnet and pulled the instrumentation fuses in the passenger footwell and they're fine. I've disconnected the battery and left it for an hour or so in case it all went back to normal of its own accord but no such luck. I don't know why an earth connection being remade should spark - capacitor discharging maybe? All the wires were connected to the earth terminal before (however tentatively) so that probably rules out a dead short
So the fault has to do with the earth wires you moved and reconnected.
Some earth wires become LIVE with the ignition on. Wriggling about a poor connection can cause it to make and break the current flow.

When it connects there will be no arcing or spike in the current flow. However as the connection breaks that is when a spike is generated. This can be a surge of very high voltage that can upset some of the more delicate electronic components in the cars electrical system.

It always pays, when working on the cars electrical system, to disconnect the battery earth terminal.

I know most if this won't help as much as some of the posts above but might give you a guide into where to look to solve your problem.--
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