Resistance Question

[Zero]

Question: I am interested in tapping into the engine sensors on
my car, doing it the old fashion way - hardwire ( Yes, I know about
OBD II - not suitable for my application).

The temp. sensors are just variable-resistance sensor, but I dont want
to tap into line if its going to throw off the car's computer. What I
want to do is be able to pull the values of the sensors, say ... into
another gauge, but dont want to throw off other gauges and the
computer reading the resistance


For the technical people, What I am wanting to accomplish is to have a
pc/laptop, pulling the resistance of the sensors in thought the game
port, which will allow for 4 resistor readings, and have them logged.

There shouldnt be a voltage going across the ground resistance of the
sensors, as in a standard voltage gauge which moves a needle based on
voltage drops with ground resistance.


*** Any help/comments/questions about this is welcomed !!! ***




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[JeffM]

I am interested in tapping into the engine sensors
I [want] to...have a pc/laptop...the game port
Zero

You will likely destroy the game port.
An automobile electrical system has voltages beyond what you imagine.

 

[Zero]

Hmm, Thats Odd. The sensors use resistance to ground. I currently have
many different types of sensors being logged by a couple of differnet
game ports in the house. The question was: would tapping into and
aquiring the resistance value from a sensor effect the ECU of a car
(beyond a tollerable level).

Again - There is NO voltage across the sensors, just resistance.



On 24 Jun 2004 14:28:23 -0700, jeffm_@email.com (JeffM) wrote:

I am interested in tapping into the engine sensors
I [want] to...have a pc/laptop...the game port
Zero

You will likely destroy the game port.
An automobile electrical system has voltages beyond what you imagine.

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[JeffM]

I am interested in tapping into the engine sensors
I [want] to...have a pc/laptop...the game port
Zero

You will likely destroy the game port.
An automobile electrical system has voltages beyond what you imagine.
JeffM

There is NO voltage across the sensors, just resistance.
Zero

If the original instrumentatation is reading the sensor,
it is applying juice to it to do that.
You are also not considering the spikes that happen in a car.

 

[mrnobby]

"Zero" <Zero@Home.net> wrote in message
news:l3crd0tts6ijjsfnhd40p9mvr948louprk@4ax.com...

Hmm, Thats Odd. The sensors use resistance to ground. I currently have
many different types of sensors being logged by a couple of differnet
game ports in the house. The question was: would tapping into and
aquiring the resistance value from a sensor effect the ECU of a car
(beyond a tollerable level).

Again - There is NO voltage across the sensors, just resistance.

Dude Zero,

If you knew the 1st thing about electricity, you would know that when a
current flows through a resistor (i.e there is a potential difference
between both terminals) then there is a voltage drop across the
resistance.

To get the resistance value accurately, you would have to disconnect the
sensor from the circuit totally, and measure the resistance with a high
impedance device such as a digital multimeter or an oscilloscope.

But I suggest you learn the fundamentals of electricity before you
dabble with your ECU first.