Re: 1937 Wiring Issue

Posted by HH56 On 2021/8/21 11:36:12

Troubleshooting with a volt meter is sometimes tricky. It may take a current reading along with the volt reading as well as some deduction to decide if something else in a circuit is skewing the results.

Your meter could be reading through something that is connected and just sitting there but in perfectly normal condition. The meter has a high internal resistance and while it can measure voltage on both sides of an item, there is too much resistance in the meter to let enough current flow for the item to actually do anything.

A good example would be reading thru a coil or a bulb filament permanently connected on one side. As long as the coil winding or filament was intact the meter would read the supply voltage on one side and then the same voltage would go thru the item and appear at the terminal on the other side as well as every other item on the car that same terminal might be connected to. Even though the voltage reading is present, the coil or filament would not do anything until a solid connection to the return side of the battery was made on that terminal to provide the current needed for the item to operate.

With the partial voltage you are reading it could be normal voltage drop thru a resistance but at that low a voltage it could also be that a resistance to ground has developed on a wire or component also connected to the side you are measuring -- high enough to lower a voltage and provide a bit of current flow but not low enough to permit sufficient current to flow thru the component to energize the item.

If you had a wiring diagram showing exactly which wires you have removed and what and where you are measuring that might help in narrowing down what else could be connected and worth looking into or what might be happening.