I'v just noticed a high pitch whine coming from the engine compartment when I switch the main lights on and stops when I switch them off. Could this be coming from the alternator or just the fan belt?. Any ideas please.
Probably alternator. When you switch lights on and other high demand electric parts the alternator has to work harder to supply the demand. So it is harder to spin the alternator and this leads to pressure on the alternator bearings. Live with it untill its really noisy or wont charge the battery.