Which module is connected to the throttle?

I'm trying to diagnose a P2102 Throttle actuator control motor circuit low DTC, and will post about it soon, but first, can someone tell me what to call these three modules? And does anyone have the diagram showing the connectors at each end for the TB control motor, and maybe the sensor circuits also? I need to check continuity of the wires. The TB motor resistance read within specs.

I'm guessing that the module on the left of the three under the dash is the one that connects to the TB.
I'm guessing that the module by the fuse box in the engine compartment is for the hybrid system.
I'm having no luck online finding credible info on these modules.

If I have replace one of the interior modules, how do they come out? The empty bay has a plastic hook, but I don't see that under the other three. Those wire bundles look hard to move.

 

P2102 Throttle Actuator Control Motor Circuit Low

Context:
2010 Prius, regular model, about 210k miles, using about a quart / week, not from leaks. Driven several hours/dy, city+idling, 100F days (Doordash delivery).

9 mo: ABS code after a predatory towing. I assume they damaged a signal wire with safety chains, but the motor was running and the parking brake on when I left the car and that's the way I found the next morning in the impound lot. (Plus the ABS light on).

3 mo: EGR codes that came and went every few days. (Had I known then, what I know now, I'd have jumped on that earlier.)

2 wk: Headlight system error when using lights. (Prev, only when wet). Only light not working was the top orange parking light on the front left that was damaged in a fender bender, but otherwise still operational. (I have the replacement assembly, but too hot and exhausted to prioritize it yet.)

2 mo: Had to trickle charge the battery, starting at every 2 weeks, then every morning during the last few days. I was going to monitor the current at the battery while pulling fuses, but when I got everything ready, the 1 amp draw was gone. The battery is maintaining charge now.

0 dy: pulling into driveway, car dies. I start it and get it the rest of the way in. I try to drive it around the block but it dies part way. I restart and barely make it home. At this time, in addition to the ABS, headlight, EGR and hybrid system codes, I have the three throttle codes. If I clear them and try to start, the throttle codes return instantly. The engine will run for 1-3 seconds and quit.

The TB had some oil in it (I assume from the EGR being clogged. Hopefully the head gasket is still good, but I've replaced one before, on a 2013, so that's not the end of the world. The 2013 wasn't using oil. Go figure. But the dealership failed to diagnose the head gasket. Go figure. Except for a water pump replacement a few months later, it ran great after new gasket, until it was totaled.)
I cleaned the throttle plate, removed the pool of oil.
I had seen several vids that used a 12v battery to test the TB motor. I now feel that was stupid, as I suspect my TB uses 5v and PWM signals.
Connected one way, the throttle plate slammed close. The other way, it chattered.
End of context

===========================================
The TB motor connections meter at 3.4 ohms. (I don't have the specs for gen 3, but that is in range for gen 2: 0.3 to 100 : at 68F).)
The wires meter at 1.4 ohms (gen 2 spec is below 1 ohm). I doubt the extra 0.4 ohms would make that much difference. This is using the connector to the ECM by the fuse box, which I trust to be the D28 in the wiring diagram that I downloaded from Scribr, pins 20 and 21, as indicated. Diagram matches actual connector. Since these showed continuity, I feel confident that I have the right path.
I can't find a body ground to check the resistance of the motor connections to ground.
I have checked all the fuses, but none of the relays.

From the symptoms, it seems like I had a short some where, probably inside the ECM or in the wiring harness, that eventually burned out into an open, thus the P2102 suddenly.

Hoping some experts will help me sort this out. (TIA)

If the wire resistance is too high, it doesn't explain the increasing battery drain and then no drain.
I'm guessing that only leaves the ECM.
I see refurbished units online for about $150, preprogrammed for a specified VIN and including a tool to sync with the immobilzer, if needed.
If the ECM is the only logical culprit, I can replace it and if needed, tow it to dealership to sync or perform their own troubleshooting.
I have Techstream, but I'm guessing Toyota requires key codes only available from their paid services, like the key fob reprogramming.
I assume the online seller's tool is like the tool that a locksmith used to replace my lost key a few months ago, bypassing Toyota's key codes.

1) Why can't I find a body ground in the engine compartment? (Or maybe I'm doing it wrong. With connectors off on both ends of harness, I'm testing between TB motor's connectors and every metal part I can find. Not sure if it's all aluminum and plastic?) I think I'll try to run a wire back to the battery, just to be thorough.
Also, isn't there supposed to be a jump start connection in the eng compartment? I can't find it.

2) If it were you, and $$ is scarce, would you just order the refurbished ECM?

3) Since I was able to get continuity on the harness, can I trust that the ECM by the fuse box is the correct suspect, not anything in the dash? Only reason I ask, is there are so many things online that tell me the throttle is controlled by that ECU. Can there be a throttle motor only power circuit into the ECM? Perhaps in a relay?

4) Can anyone confirm the 5v/PWM theory? Just curious, and disappointed that info isn't readily findable.

Again, TIA for any expert advice!

 

Here were the codes when it died the second time:

P0300 Random/Multiple Cylinder Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0304 Cylinder 4 Misfire Detected
P0401 Exhaust Gas Recirculation Flow Insufficient Detected
P2102 Throttle Actuator Control Motor Circuit Low
P2112 Throttle Actuator Control System - Stuck Closed
P2119 Throttle Actuator Control Throttle Body Range/Performance
P0A0F Engine Failed to Start
P0A80 Replace Hybrid Battery Pack
C2300 Actuator System Malfunction
also C1231, C1241, C1380 (ABS); B2430, U0155, B2312
I think after clearing DTCs, only the Throttle codes return.