Thanks Dennis.

In hindsight, I recall reference to the 5 Volt test spec shown in the
A3 Bentley but assumed it was only for things like the TPS (as on
Jetta) etc.

My question is moot!

If a given sensor connected to ECU was seeing anywhere near 12 Volts,
something would be horribly wrong.

Neil.

On Sat, Sep 28, 2013 at 6:15 AM, Dennis Haynes <d23haynes57@hotmail.com> wrote:

> If you want to be "electrically obsessed, learn Ohm's and Kirchhoff's laws. Add the formulae for power and the will be no DC circuits you can’t figure out.
> Then for working on programmable logic controllers, (PLC's) and most other ECU controlled stuff you need to understand the difference between sinking and sourcing circuits. This can get confusing as outside a battery current is actually flowing form - to +.
> Most work done on semi-conductor based controllers works off 5 volts. The VW ECUs are no exception. The sensors except for O2 are sinking.  In other words, there is a 5 volt supply that feeds all the sensing circuits. The temp sensors sinks that circuit to the chassis. As the sensor warms up the resistance goes down, current increases and voltage drops.
>
> Even the gauges operate at some voltage below battery. This is done so system voltage does not affect gauge readings.
>
> So those numbers in the real world are possibly meaningless.
>
> Dennis
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of neil n
> Sent: Friday, September 27, 2013 1:49 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Temp II (for ECU) Sensor: Voltage Range?
>
>
> Do aftermarket unmarked sensors possibly fail early due to a limited voltage range?

-- 
Neil n

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