Hello,
Please help me understand the following problem:
I charge my battery with the ground wire completely disconnected from the negative bushing.
when the trunk is closed (open circuit at the trunk light bulb) and I open one of the doors, the door opening indicator and/or brake level indicator lights up very weakly at the instrument block!
What do you think?
Every appliance and lamp in the car requires a +ve and a -ve (ground) to operate
Your door open/low fluid level lamp has a +ve connection to the battery via the switches and fuse, but if you've disconnected the ground wire at the battery it won't have a -ve connection and therefore cannot light, it simply does not have 12V at the lamp, even with the battery charger connected. I think the fact that you first noticed it when the charger was connected is misleading you
So, if it does not have a -ve to complete the circuit, where is it getting a voltage from?
Does your trunk light illuminate when you open it, with the earth strap disconnected?, i understand that this should have a permanent feed, ie it operates without the need for the car lights to be switched on, so in theory this should also show dim at the same time as the door open light
I'm still of the opinion that the battery is leaking and causing a small current to find its way around the circuit, has your door open lamp been replaced with an LED at any time?, this may explain why it's illuminating dimly, it may only need a tiny voltage/current to light up, whereas other lamps will need a decent voltage to light up, even dimly
I would still try insulating the battery completely from all metalwork, remove the clamps, and stand the battery on insulating material, a rubber mat or similar, or simply try and hold the battery in mid air and simulate the problem
You seem to be having to charge the battery regularly?, perhaps it is failing internally and it's time to replace it
