RealTesla

There's certainly two links from BC Front to the EPAS (I keep calling it IPAS for no good reason). And they're absolutely labeled BATT1 and BATT2. BATT1 is labeled elsewhere in the diagrams as 12v, which I presume means BATT2 means HVDC. But all of the other HV components are called out as HV in some manner, whereas the EPAS just says BATT2. I'm assuming this is tapping the HVDC power in the BC front, though.

Now, having looked at the wiring diagram, I'm wondering something about all the EPAS warning posts we've seen on forums over the years. It almost always seems to be related to a faulty ground or a faulty 12v battery connection somewhere, or on rare occasion a dying 12v battery. So now I'm wondering whether the EPAS controller is actually experiencing a fault because of low control circuit voltage or if there's something else going on here. And if it's the latter, could it manifest as low supply voltage to the DSP / ADC for the APP sensors?

Ultimately, most of these systems are fused with a FET and current sensors. So you would imagine that Tesla would have detailed logs somewhere in the system about supply voltages and current to all these peripherals. I'd love to see what that data looks like in a scenario where the EPAS warning is triggered, or on a vehicle that's stationary but receives steering input. Certainly 1.2kW is absolutely nothing to the HV pack, but if it's going through the same DC/DC that charges the 12v battery, it seems possible that the current could be too high and it could trigger some voltage sag. But the fact that these are all such common circuit designs, I'm just not sure I understand how it went so wrong.

Ok, double comment time. So, reviewing this video: https://www.youtube.com/watch?v=rDYbvI32OBE

At 2:27 he pans across the EPAS module and the BATT1 and BATT2 connectors look exactly the same to me. They are not HVDC cables with the typical bright orange sheath, but rather just red and black. I think this is just two 12v sources. One is likely the DC/DC converter and the other is likely the battery. But for sure there's no HV connection here and there's no secondary battery source, it would actually just be that DC/DC converter being called "batt2".

Odd design, but here we are. I'm positive there's no secondary 12v source here and that it's just feeding from "redundant" controller boards and everything feeds through the 12v battery. But I'm just open to the possibility there might be two sources on the body controllers. Again, all would be sourced from the battery and the DC/DC converter would feed through it, but that battery is in the way of all of this and is not actually redundant at all.