I have parts from a 2015 70D...There is current measurement after the fets, see the curled up busbar.
Wait a minute, why would the fets control the HV to the 'grey' HV connector and measure current?
So would this mean that the PTC heater (water???) be a dumb module? Ah 2013 module looking at some info the battery heater just needs a pwm into the junction box.
Plus nice isolation devices (Big SMD packages) just like on the bms slaves.
1) the PTC Cabin Heater operates from CAN. Like some of the other Tesla modules, it has a Tesla designed control board that drives a main board. I did see some recent hacking by others on controlling the mainboard IGBTs directly. The heater is fairly large and I'm 50/50 I can get it to fit into my airbox. I'm hoping Damien gets a look at it.
2) the Air Conditioning Compressor was also CAN controlled. I also bought a 2014 Tesla compressor which is reportedly PWM controlled, but I haven't done any experimenting with it yet (not an easy thing to test without already being in a system) - probably something better learned from a working 2014 Model S.
3) The coolant heater (battery heater) looks like the not intelligent device. Previous suggestions were that a PWM signal to the Front HVJB controlled the power to the heater. My battery (A123 from a 2014 Chevy Spark) already has an integrated heater (controlled locally within the BMS) so I may just be using the heater for cabin heat (assuming I can't get the PTC heater jammed in).
4) The DCDC also has a direct CAN connection. Interestingly in my DCDC there is no Tesla branded board. I'm hoping that the device will simply report CAN out rather than need CAN to operate (at least beyond a 'fail safe' mode). It's only the list of things to test next. I'm also hoping Damien will tackle the DCDC.
Jeff