Voltage to the Intelligent Parking Assist ECU

The “(BAT)” notation above the RAD NO. 1 fuse in the upper-left corner means the source is the auxiliary battery, nominally 12 volts DC, but in practice ranging from 11 to 14 volts or so.

Note that the wiring diagram you posted is for Prius cars sold in North America. You might find it worthwhile to subscribe to toyota-tech.eu (from €3 for one hour), where Toyota has published the Repair Manual (RM12A6E) and Electrical Wiring Diagram (EM12A6E.V.1) for vehicles sold in Europe.

In the Repair Manual, I’d suggest looking in the “Advanced Parking Guidance System” and “Rear View Monitor System” sections; the pages “System Diagram” and “Terminals of ECU” may contain the information you need, and there are also pages for circuits (such as “ECU Power Source Circuit” and “Reverse Signal Circuit”) and symptoms (such as “Image from camera for advanced parking guidance is abnormal”) that may be relevant.

 

You’re welcome, and in principle, I think it could work. I haven’t reviewed the complete specifications of the converter, however, nor considered how it should be fused or whether the added electrical load might cause any problems.

(Indeed, while I’m happy to discuss modifications, my recommendation is not to modify your car at all, except perhaps by installing Genuine Toyota Accessories.)

Yes, since the U.S. and European versions have different part numbers. Without having compared the manuals and wiring diagrams, I don’t know whether this is only because the firmware is different, or if there are also physical or electrical differences.

 

Use the information in the Repair Manual, adapting it for the changes you’ve made.

Check the power supply first. Use a multimeter set to DC volts to check that the voltage required by the camera (5.8 to 7.0 volts DC) is present at the output of your 6-volt converter and also at the camera connector, on the correct pins (that is, with the correct + and − polarity).

Reconnect the camera, and use an oscilloscope or television waveform monitor to check the video signal coming from the camera; the Repair Manual has examples of the expected waveform, with synchronizing pulses and video. If you don’t have either of those instruments, you should be able to use some other device with a composite analog video (NTSC) input to view the picture.

On an RCA connector for video, the center pin is typically connected to the insulated wire, and the outer ring is typically connected to the cable shield, but use a multimeter to check that this is true for your cable.

 

I wouldn’t worry about an oscilloscope for now, but if you don’t already have a digital multimeter (DMM), I’d suggest buying one; it’s an inexpensive, essential tool for automotive work. Since you won’t be using it on circuits with dangerous voltages (like those in the orange-colored wires of the hybrid system), any basic multimeter—similar to those found in the U.S. at home improvement stores for $10 to $30—would be fine.

It depends on where the six-volt power for the Rear Television Camera Assembly is coming from. If the camera is still connected to the Parking Assist ECU, then this could be so. If the power wires going the camera are connected instead to the output of your 12-volt to 6-volt converter, then the camera should be powered whenever the converter is, regardless of the shift position.

Indeed, this is something else to think about: if you connect your converter’s input to an unswitched circuit—like the wire from the battery providing 12 volts to the Parking Assist ECU—then the converter could eventually drain the battery, since it will always be drawing current, even when the car is off and the 12-volt battery isn’t being recharged. The Parking Assist ECU switches itself off (or into a low-power mode) to avoid this, but your converter doesn’t have such a function. You might want to connect the converter’s input to an (ACC) or (IG) circuit instead, since these are only switched on when the car is in accessory mode or running.

 

You’re most welcome, and I’m glad to see it’s working.

 

Hi I am also thinking of buying an android headunit. Is your IPA working with your headunit? because you have cut wires 11to 14, so the ECU will not send parkingninformation to the headunit