Pulldown resistors for TPS MAP

[T Hergen]

Of course, if I had read the subject line more carefully, I would have
realized I was off topic...

The comments I made apply to the temp sensors, not TPS and MAP...

Sorry for the confusion.

Tom

On Mon, 3 Aug 1998, T Hergen wrote:

> Here's some possible values...
> 
> Peter indicated the that some gm ecms switch in a 348 Ohm or 4 KOhm pullup
> (see his 7/31/98 post).  Looking at the temp vs resistance tables for a
> CTS and IAT, there is quite a range to cover.  Over 100K for very low
> temps and about 177 Ohm around 100C.  The 348 Ohm resistor would likely be
> switched in at the higher temps.
> 
> Given this range, a 100 KOhm log taper potentiometer would work.  Use only
> two terminals, the wiper and the one that shows 100 KOhm at one end and
> much less than 50 KOhm when the shaft is in the center position.
> 
> With a 100 KOhm pot it will be difficult to adjust the high temperature
> end of the scale with any precision.  For this reason, it would be nice to
> be able to switch in a 5 KOhm to 1 KOhm pot (again using only two
> terminals) to cover this range. This "user" switching of pots is
> independent of when the ecm decides to switch in a different pullup.
> 
> Adding a 100 Ohm resistor in series with the wire to the ecm temperature
> input would reduce the peak current that could be drawn and reduce the
> chance of damaging the ecm.
> 
> Does anyone know if the 730 or 165 ecms are ones that really do switch the
> pullups?
> 
> Thanks,
> Tom
>