Electrical Gremling

[steve157]

To all the electrical wizards, I have a annoying fault in my electrical system the trim gauges and rev counters work intermittently(better when the engines have been running for a while???) also when I turn on the engine room blowers the 27meg radio is affected.What would be the most likely fault would it be a bad earth or something else I have checked behind the dials but cant find any loose wires. Any help would be greatly received.

 

[savageseadog]

You need to check your main feed wiring first, all the battery negative and positive connections the on/off changeover switch etc. If you cant fing it use a meter connect the negative of it to your common grounding point which will either be a busbar the engine block or the battery negatives. Then connect to the main 12V common point. You should read the same voltage when loads are put on, the starter will drop between 1 to 3V depending on the state of your batteries. As long as that is the case measure the 12v supply closer to the actual load, for a small load like lighting you should not see much change in voltage.
The sort of problems you are having are often caused by bad wiring practice. You have to use adequately thick cable and split the loads sensibly. Don't forget you need as good a negative cable as a positive one for each circuit.

 

[steve157]

Thanks for that gives me somewhere to start.