Quite often when idling my lights dim & flicker esp when the stereo & heater etc are on. I've replaced the battery with a new Bosch Silver one and uprated the earth's but to no avail, is there anything else that can be done? Should I get the alternator checked to make sure it's operating correctly?

 

Yep.. It should charge at no less than 12.5 - 13V. Stick a Multi meter on it and see.

 

I get a good 14.5V on the gauge on the dash but sometime when I stop at a junction etc the voltage jumps about?

 

Double check it at the Alternator with a meter. Turn everything on and hold it at about 3000 RPM..

 

Checked all the earths etc and they're good. Replaced the alternator to +ve on battery with a 4gauge and still the same problem. I can watch the voltmeter on the dash bounce between 14.5v and 12v as I turn the volume up. Surely this should not be happening with just one amp running a pair of components? Could it be the amp earth needs to be improved further? Suggestions please?

 

Cheak all the cables. There may be a short circuit or something incorrectly wired. Maybe try earthing to a different part of the chassis. Do all pos and neg go to the right places?

 

All checked, nothing seems to be amiss.

 

If you are sure the fault is around the ICE then if it were me I'd rule parts out by disconnecting the wires to each component. Or check each wire end to end with the meter. You will need to know what voltage you are feeding in. eg. 12V at one end you should be getting the same at the other end, or very near to, any less then a short is present. It would have been my guess that something was incorrectly wired say a + from the back of the head unit to a - on a speaker for example. Could a speaker be earthing on the rear shelf? Faulty sheathing? Faulty component? Do you have sooo much ICE that the Alternator doesn't cope? Faulty Battery?

Other than that I'm all out of ideas. Sorry.