Possible Alternator issue?
My 2000 Diplomat dash volt gauge,under load and/or sitting idle, will read 13+ until I turn on the lights. It then will show 12.5 and drop below 12 with constant light usage. This makes it impossible to drive at night or in the rain. No alternator light blinks or shows. Wiper usage has the same effect.
Would this be a definate weak or failing alternator? I have changed the house and chassie batteries without any change to the issue.
2000 Monaco Diplomat