A 2023 Toyota Prius does not have a traditional alternator — that’s why you’re not finding one.
The 12V battery is charged by a DC-DC Converter inside the hybrid inverter assembly, which steps down power from the high-voltage hybrid battery. The engine also has two motor-generators (MG1 / MG2) inside the transaxle that act as generators.
If your 12V system isn’t charging, 99% of the time people mean the DC-DC Converter / Inverter assembly. Replacing it is a HIGH VOLTAGE job.
*WARNING: The hybrid system has 220+ volts. It can seriously injure or kill you if you don’t disable it properly. If you’re not experienced with hybrids, have Toyota do this. Wear insulated gloves rated for high voltage.*
Here are the steps for the 2023 Prius (5th Gen, MXWH60):
1. Confirm You Actually Need It
Symptoms of DC-DC failure: 12V battery light on, 12V battery keeps dying, DTCs like P0A94, P1A10, P0560
Test first: Check 12V battery health, check 120A DC/DC fuse in engine bay fuse box, check 12V voltage with car in READY — should be 13.8-14.8V. If it’s 12.0-12.6V in READY, converter isn’t charging.
2. Tools and Parts Needed
New DC-DC converter / inverter assembly — part # depends on FWD vs AWD
– 10mm, 12mm sockets, insulated tools
– High voltage insulated gloves (Class 0, 1000V rated)
– OBD2 scanner to clear codes
– Torque wrench
3. Safety Shutdown — Most Important Step
1. Turn car OFF, remove key fob 15+ feet away
2. Disconnect 12V negative terminal in trunk (10mm). Tape it.
3. Remove rear seat bottom cushion. Disconnect the orange High Voltage service plug on the hybrid battery. Wait 10 minutes for capacitors to discharge.
4. DO NOT touch any orange high-voltage cables.
4. Access the Inverter / DC-DC Converter
1. Open hood. The inverter assembly is the large silver box on top of the engine with orange cables and “High Voltage” warnings.
2. Remove engine cover and air intake duct for space.
3. Drain inverter coolant: Place pan under radiator, open inverter coolant drain (separate reservoir from engine coolant on this generation). It uses Toyota SLLC pink coolant.
5. Remove the Inverter Assembly
1. Disconnect all low-voltage connectors on the inverter (4-5 connectors)
2. Disconnect orange high-voltage cables — use insulated gloves. Cover terminals with electrical tape.
3. Disconnect 2 coolant hoses from inverter
4. Remove 4-6 mounting bolts/brackets holding inverter to chassis/transaxle (12mm)
5. Carefully lift straight up — it weighs about 35 lbs. Get help.
6. Install New Assembly
1. Transfer any brackets to new unit
2. Set new inverter in place. Torque mounting bolts to 18 ft-lbs
3. Reconnect coolant hoses and refill inverter coolant reservoir
4. Reconnect high-voltage orange cables first — torque to spec (71 in-lbs typically). Click must be heard.
5. Reconnect low-voltage connectors
6. Bleed inverter coolant: With car in IG-ON (not READY), use scan tool to run inverter water pump active test, or run car in READY for 30 sec intervals while adding coolant until no bubbles.
7. Re-Initialize and Test
1. Reconnect High Voltage service plug (3 steps: insert, pivot lever down, slide lock)
2. Reconnect 12V negative terminal
3. Start car to READY mode. Check for warning lights.
4. Measure voltage at 12V battery jump point under hood — should now read 14.0-14.8V
5. Clear DTCs, test drive, recheck for coolant leaks.
If you actually meant the belt-driven alternator on a NON-hybrid car: The 2023 Prius doesn’t have one. Some shops mistakenly call the MG1 inside the transmission an “alternator” — that requires dropping the entire hybrid transaxle and is a 10+ hour professional job, not a DIY.