This problem is on a 96 Dodge Ram 1500 pickup, but I'm sure it could relate to any vehicle made since running headlights was introduced a few years ago.
That's it: the headlights stay on even when the motor is not running; they obviously drain the battery, so I've taken to disconnecting it when I park.
Nowhere yet have I found how the running lights are wired (by design), but I suspect the easiest way would be by putting a diode in the charging circuit so current can flow only from the alternator to the battery, with an extra feed wire for the headlights taking power from the alternator end of the diode. That way, the lights would be 'permanently' ON whenever the motor is running, but could not draw current from the battery when it's not, because of blocking by the diode.
Diodes usually 'blow' ie., burn out, breaking the circuit, which would not produce this fault, but would actually stop the charging of the battery from the alternator; but they occasionally 'short out', which WOULD produce this fault, since it's no longer acting as a diode, but rather a conductor in both directions, so battery charging would still happen normally when the engine is running, but the lights would stay on when it's not.
I'd appreciate any comments from anyone who either has run into this problem befrore, or anyone who knows how running lights are wired so that they are always on when the engine is running. Thanks
That's it: the headlights stay on even when the motor is not running; they obviously drain the battery, so I've taken to disconnecting it when I park.
Nowhere yet have I found how the running lights are wired (by design), but I suspect the easiest way would be by putting a diode in the charging circuit so current can flow only from the alternator to the battery, with an extra feed wire for the headlights taking power from the alternator end of the diode. That way, the lights would be 'permanently' ON whenever the motor is running, but could not draw current from the battery when it's not, because of blocking by the diode.
Diodes usually 'blow' ie., burn out, breaking the circuit, which would not produce this fault, but would actually stop the charging of the battery from the alternator; but they occasionally 'short out', which WOULD produce this fault, since it's no longer acting as a diode, but rather a conductor in both directions, so battery charging would still happen normally when the engine is running, but the lights would stay on when it's not.
I'd appreciate any comments from anyone who either has run into this problem befrore, or anyone who knows how running lights are wired so that they are always on when the engine is running. Thanks
Aug 28, 2007 at 8:59 PM