Neutral Switch fuzzy ground signal

Hi there

I'm new here and just as good as average beginner in electronics. I'm a old programmer and done a lot of heavy stuff in that department. I know simple terms and understand somehow some basic concepts as transistors, relays, resistors, diode, capacitors and can I have made some simple logic gate's when I was younger.

The problem I'm facing is I think a simple one for you guys. I have a a circuit for motorcycle to show what gear it is in, i.e. Gear Indicator. Ok. I bought this very cheap from China. Every thing works as it should on the bench.. that is, until I test it in the bike.

The neutral wire was supposed to return 0v when in neutral (no gear), otherwise it returns 12v (for every other gear setting's) which is the main voltage on the bike. The problem is, the neutral sensor is is not returning 0v when the bike is in neutral. It's returning 0.5 something volts which is not low enough for the gear indicator circuit to trigger neutral. I haven't bother to contact the manufacturer but I did some simple resistors to ground check and with I think with 10ohm resistor I got 0.22V (if I remember right) and that did trigger the gear indicator properly.. but of cause that kind of resistor allows to much power drain and not usable when the bike is running in gears and the signal is 12V.

So.. I must add some extremely simple way to kind of "mask" all low voltage to almost zero without affecting 12v. That is, at least all voltage below 1V should be masked down to as close to 0V (0.1-0.2V seems to be enough)

Any idea how to do that without drawing current when signal is 12V?

https://www.the12volt.com/installbay/forum_posts.asp?tid=114792&kw=2n6491#556471

Left leg in picture to neutral output wire that is not going all the way to ground. Right leg goes to your remote start unit.

i am an idiot wrote:

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https://www.the12volt.com/installbay/forum_posts.asp?tid=114792&kw=2n6491#556471

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Ok.. relay or mosfet was one of my idea's.. but the problem is I don't want the relay to open when the sensor is 12v or open (in gear 1..6), just when it is around 0.5-1.5v or so and in neutral.

Then I was wandering.. can I instead use ground and 12v as trigger current, use instead 12v from other power source as the battery and the power from sensor to trigger the relay? With the idea that 12v and 12v will not trigger the relay, but 0.5v and 12v will.. which is of cause my goal.