VemsAudiAan mot55/pin41 A/C idle up => voltage divider to protect mch3 (raw extra ADC mcp3208/3 ).
We assumed it is 5V or "12V", and 0V when off.
The mch3 has an 1 + 100k / 75k voltage divider (from EGT2 ad597 output), so
68k series with the 100k (in heatshrink coming from mot55/pin41) makes the voltage dividor ratio:
- 1 + 168k / 75k
- Vdiv=1+168/75 ( = 3.24 )
- V=[5, 12, 16]
- V ./ div = 1.54 3.70 4.94
So dividing 5, 12 and 16V to => 1.54V, 3.7V and 4.94V respectively (activation threshold is normally around 0.9 .. 1V). So it should clearly detect on and off condition. (and apparently it does, A/C idle up function became popular).
Please edit:
What raw voltage do you see in view gauges / raw ADC ( mch3 ) when A/C clutch is on and off ?