Originally Posted by
kur4o
I will dig out some conformation about it, and how it is done. It is not possible to get a linear signal from a 5kohms to 100 ohm signal drop.
Don't worry about it - it's not going to pose a problem. I'll simply build a lookup table that goes something like:
Code:
[adc_raw_value],[coolant_temp],[coil_temp]
730,50c,<user configurable>
715,52c,<user configurable>
700,55c,<user configurable>
670,57c,<user configurable>
... (need to collect more data points but you get the idea)
288,38c,<user configurable>
240,44c,<user configurable>
200,48c,<user configurable>
190,50c,<user configurable>
The PCM is doing all the heavy lifting here - the ignition controller is just listening passively.
Edit:
Originally Posted by
kur4o
I have seen this at a lot of gm code. 2 coolant tables switched by some mystery reason with a hardware switch. Never could figure it out
Just wanted to add / clarify - in this case there's significant signal transformation going on behind the scenes here - as you say likely on the t-side. But the "raw" ADC value in the ALDL datastream was perfectly linear. I imagine they started doing this out of necessity when the Y-body engineers wanted to start showing a digital coolant temp in the DIC / CCM.
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