Coolant temp sensor circuitry, injector lugs

[Rich Mauruschat]

At 10:48 10/07/97 +1000, you wrote:
>What method do most efi computers use for measuring the resistance of
>the coolant temp sensor - a wheatstone bridge, a constand current
>source, or perhaps just a potential divider type setup?  (This question
>may have been more appropriate for the efi332 list)
>
>Also, the injector connectors used on late model Mazda engines, some
>Mitsubishi's etc - what are they, where can the lugs that fit in them be
>found?
>
>thanks
>
>
>
Generally (in the stuff that we see in the UK at least) the coolant sensor
is connected as the bottom half of a potential divider with a pull-up
resistor to supply, generally 5V logic supply. The signal is then taken from
the divider junction. A popular value of pull-up resistor is approx. 1K8
ohms where the sensor resistance at 20C is approx. 2K ohms, at 100C approx.
180 ohms. (this seems to be the case for Bosch systems at least; Ford have a
tendency to use a higher resistance sensor). Occasionally a constant current
source is used. An interesting deviation from this is found in some of the
later GM Multec systems (Opel/Vauxhall) where the pull-up resistor is
switched part way through the range to improve the resolution at the range
extremes.
Hope this helps
Richard.