Slipper man Posted June 20, 2011 Share Posted June 20, 2011 I have discovered that my tow bar socket was incorrectly wired and that the foglight terminal was wired to the reversing light. In the process of fixing this, I discovered that the earth terminal of the socket had around 0.3v relative to the car's chassis. I presume this is why when you flashed the indicators, all the trailer lights dimmed in synch. What I can't understand is where this voltage comes from. I have solved the problem by attaching a separate earth directly to the chassis, but without knowing why there was a voltage there in the first place I am afraid that all I have done is bodge it, which doesn't make me feel comfortable. Can anyone explain the voltage across the earth terminal to the vehicle chassis? Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 20, 2011 Share Posted June 20, 2011 Don't think 0.3V is a great concern. Fitting good earths will resolve any such floating voltages. It is invariably a bad earth connection when you see cars with brake light/indicator problems. Link to comment Share on other sites More sharing options...
rj Posted June 21, 2011 Share Posted June 21, 2011 As Ian says: It's a bad earth connection. The voltage across could be because of two different metals for the body of the car and for the cable shoe that was supposed to provide the earth working as a galvanic cell. Salt would probably add to the issue. Watch this: here Making a new earth is the best you can do! Link to comment Share on other sites More sharing options...
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