Busskipper wrote:
Sounds like a bad GROUND.
If not at the battery check the frame connection.
Good Luck
Sounds like a possibility to me, too. The negative terminal of the battery will connect to a ground and they can get dirty. You may need to clean all of the terminals with a wire brush and disconnect the ground and scrub it.
The lights dimming when you try to start it would indicate a few different things. Either there is a bad connection or the starter is drawing too much amperage. It could be a problem with the starter, the engine, or a bad connection in the starter circuit. The most common problem is wiring connections.
The only way to really isolate it is to have a shop check the amp draw of the circuit.