On 16/07/10 06:32, Carl Denk wrote:
> Agreed on both, it's not the separate module, but,   if somewhere the
> data is saved in a similar way as an aircraft black box. :)
>
> All the throttle position sensors I have seen, have only 2 wires going
> to them and are nothing more than a variable resistance  (Pot), but
> there might be some that use optical encoders or some other method.
> There are some rough checks, though, the Mass Airflow sensor (MAP)
> should be close to how much air is going into the engine. If throttle
> closed, a minimum,  along with manifold pressure (vacuum). Probably
> along with RPM and other sensors input, there could be an algorithm, to
> check on the TPS.
>
> On the Cougar, I did check the sensor for roughness, with engine off,
> slowly open and close the throttle. Captured the output voltage readings
> with the scanner, imported to Excel, and plotted a chart. Got close to a
> straight line with no wild points. Could do same thing with a voltmeter,
> but to break into the wires, I preferred not to, to preserve the
> moisture resistance of the harness, but could have made some short
> jumper wires. The scanner was easy to do.
>    
I believe (at least in the better ones) cars that do drive by wire use a 
pair of hall effect sensors to read their position.
The sensors have to agree within a certain % or otherwise the car turns 
off basically.

pots basically being regarded as "pretty crap" in general
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