Trying to be smarter than BMW

[lifeiskaos]

ok, here's the situation. i deleted my check panel, including wiring and relays:


while i was rewiring everything, i moved my brake lining cluster warning wiring, parking brake cluster light wiring, and ABS cluster warning wiring to the engine bay. they will replace my oil level, coolant level, and washer (methanol) level. i am making a new panel to look something like this. before/after:



coolant level and methanol level are VERY straightforward. the level sensors are basically ground switches. when the circuit is grounded (low coolant, low methanol), the light turns on. oil is where it gets tricky. here is a huge diagram of the brake lining warning system:



this is where my questions started. the brake wear "sensors" are basically just a wire, than when worn, makes contact with the rotor, thus grounding the circuit, and turning the light on, right? what happens when the wire is cut? does the light stay on or off? in my situation, i'd essentially be removing one of the sensors and making a single loop. the "rotor" would turn into my "oil level sensor"

so i thought that was simple enough, and all figured out, until i started looking at the oil level sensor wiring. another huge diagram:



i want to know what the "oil static" wire is for. i realize that when full, the static wire is grounded, and when low, the dynamic side is grounded, which turns on the light, but why is the static side necessary? and what does "fault clear", just above "static oil" mean? since i'll only need to know when my oil level is low, can i just use the dynamic side, and remove the static wire? or do both static and dynamic wires need power for the sensor to function?

here is what i'm hoping i can do:



i'm not sure if any of that made any sort of sense, but i'm hoping someone understands and can answer some of my questions. thanks!

[Slangbox]

Owww my head.

[slow e30]

and this is smarter than bmw... how? sounds to me your in for a rude awakening with the wiring mess. good luck, as i know from experience.

[lifeiskaos]

and this is smarter than bmw... how? sounds to me your in for a rude awakening with the wiring mess. good luck, as i know from experience.

what wiring mess? what little wiring is left in my car has been covered with military grade heatshrink and repinned with OEM pins... wiring is what i do for a living. run along now, as you obviously have nothing useful to add.

[e30nub]

I fucking love wiring. I've only done basic stuff, but my electronics class and doing a couple other misc wiring jobs were a blast! Keep us posted.

[red325]

I'm pretty sure you are going where no man has gone before, so good luck on your quest.

[lifeiskaos]

haha thanks guys. it wouldnt take long to answer my own questions with some testing (power supply, bucket of oil, etc.), i was just hoping someone already knew. will definitely keep you posted

[OrganicMechanic]

the brake wear senors ane a loop type sensor--the wire being cut or worn through has nothing to do with grounding, but opening the circuit to activate the light. Simply put, cut wire activate light.

[lifeiskaos]

the brake wear senors ane a loop type sensor--the wire being cut or worn through has nothing to do with grounding, but opening the circuit to activate the light. Simply put, cut wire activate light.

then how come when the wire touches the rotor, without being cut, the light flickers?

edit: grounding the wire is essentially breaking the circuit anyways...

[StereoInstaller1]

then how come when the wire touches the rotor, without being cut, the light flickers?

edit: grounding the wire is essentially breaking the circuit anyways...

Why that would be, I have NFC, but if you unplug the sensor, the indicator comes on.

Open = on, beyond doubt. NFC on grounding having anything to do with it.

[whowhatwhere]

"note switch closes when sensor input is 0 volts. Sensor input is 0 volts with brake wear sensor open"

There is a current limiting resistor that when the wire touches the rotor, the voltage goes down to 0v. Same thing happens when there is no wire.

So, there is a current limited vbatt supply to the wear sensor, and the return- if it does not see vbatt- switches the light on. This may be through a relay or solid state circutry.

[lifeiskaos]

i understand how the brake system works now, but i'm still want to know more about the oil level sensor, the purpose of the static side, and if it needs power to both static and dynamic to function

[lifeiskaos]

Why that would be, I have NFC, but if you unplug the sensor, the indicator comes on.

Open = on, beyond doubt. NFC on grounding having anything to do with it.

well, when power is getting through the wire, the light is off. once it loses power, (it grounds against the rotor, or get's cut all the way, or unplugged), the light turns on.

[zedfez]

In regards to the static/dynamic issue on the oil sensor: I think that the dynamic sensor is the one that trips the light, but the static sensor is the one that turns it off. That is probably what the "Fault Clear" and Fault Set" on the diagram refer to. I know that when the oil level light goes on, if you put more oil in, it does not go off immediately.

I would try disconnecting the static sensor, and use a meter to try and figure out if the dynamic sensor works without it. My only concern would be if it does not use a simple on/off 12v signal. Remember that the level switch is connected to a solid state memory unit which controls the light. Who knows what goes on in there. If the dynamic sensor is just an open/closed switch with no internal resistance, you should be golden, otherwise good luck, resistance based sensors are beyond my knowledge.

[lifeiskaos]

just realized i never updated this thread. static and dynamic oil level sensors work 100% independently of each other, which is great news. all of my fluid level sensors are now hooked up and working great.