I'd go try to figure out why the wire produces 0.95V. Otherwise it sounds like you're playing with fire here...
A few questions...Do you know where that "12V" wire is coming from? For example, is it "power" from a switch or something, or is it some sort of low-current "control signal" ? If you don't know what the wire is for, you shouldn't be connecting things to it... or at least you shouldn't be connecting anything that draws more than a fraction of a milliamp. What's normally connected? The light is something you're adding, right?Do you get 12V without the light connected? I mean, what makes you think there should be 12V there? Ort, did you connect the light and blow something, so that there's no longer any voltage there?
just use a voltage regulator to take the voltage back up to 12V
In most older car designs the boot switch is actually a grounding device. ie the lamp is permanently supplied with a 12 volt line and the other side of the lamp then runs to the boot switch. When the boot is opened the switch actually takes this line down to the chassis of the car, so completing the circuit to the lamp. ie a "grounding " switchSo the first question you need to answer is " Does the switch have 1 or 2 terminals" If only 1 then you have a "grounding" switch. If so then I suggest that there are at least 5 possible optionsa) the 12 volts line to the lamp is defectiveb) the lamp holder connections are corrodedc) the lamp is deadd) the wire from the lamp to the switch is defectivee) the switch is defective (possibly just corroded)You have not advised the model or age of the car --all information that might get you an informative answer