Quick note on this:
Hidden in the back of the vehicle is what I believe is the 300 volt air cooled DC-DC Converter part number G9250-48011
This unit is generally sold on eBay and the like as either a 'power steering control module' or 'power steering convertor assembly'. So I think it's a step-down converter that does not put out 12v.
Googling the RX400h electric power steering specifications, I found one document here
https://techinfo.toyota.com/techInfoPor ... rx400h.pdf which states the EPS is rated at 42v.
Another Toyota doc says 46v
https://techinfo.toyota.com/techInfoPor ... 0h_erg.pdf, but most references are for 42v
The 42v comes out of the yellow cables.
This link
https://www.mri-auto-diagnostics.com/c1 ... us-rx400h/ details guidelines for debugging inoperative power steering on an RX400h. It includes two handy wiring diagrams.
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These are the diagnostic instructions:
Testing:
- Check for 42 volts on the White wire at the Power Steering ECU connector (P47 – 1).
- If there is voltage, the converter is good. Suspect Power Steering ECU.
- If there is no voltage, disconnect Power Steering ECU connector, start the car, and apply 12V to Yellow/Black wire (P41 – 11). This is 12 volts coming from the Power Steering ECU to tell the Power Steering Converter to output the 42 volts. 42V should now appear at the White wire (P47 – 1).
- If there is no voltage, verify that between the Red wire and the Blue wire at the Power Steering Converter there is at least 288V when the ready light is on. Check fuse if there is no voltage. Fuse is replaced together with the Main Relay.
- If there is voltage, check Power Steering ECU power and grounds. If OK, replace Power Steering ECU.
- After replacing old PSU Module with the new one, it will need to be calibrated (Torque Sensor), otherwise, it won’t work.
This suggests to me that if you (1) ground the convertor (2) apply HV to the HV input cables and (3) apply 12v to the yellow/black wire, you should see 42V coming out the other end.
No idea on rated current, can't find that documented anywhere. Can't find a fuse either. Apparently it's fused on the inside of the pack.