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Voltage to the Intelligent Parking Assist ECU

Discussion in 'Gen 3 Prius Audio and Electronics' started by RVBPRIUS, Jul 21, 2017.

  1. RVBPRIUS

    RVBPRIUS New Member

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    I'm currently trying to find out which voltage the IPA ECU is supplied. I got the wire diagram and a picture with the wires marked below.





    Wire 1 & 3 are the power wires from the battery (light blue and white/black wires). I was wondering If I could use those wires to power the camera with use of a 12V to 6V converter (my OEM camera uses 6V).

    I'm trying to connect my OEM camera to my aftermarket Android PX5 unit. I connected the reverse wire with my aftermarket Android system, this works fine it switches to the backup camera image when I shift in reverse. But the image remains dark, presumable because the camera is not getting powered from the ECU. I did connect the video+ and - with a standard RCA cable to the Android head unit.
     
    #1 RVBPRIUS, Jul 21, 2017
    Last edited: Jul 21, 2017
  2. Elektroingenieur

    Elektroingenieur Senior Member

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    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.
     
  3. RVBPRIUS

    RVBPRIUS New Member

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    Thnx for your reply. Alright, so if I would connect the 12V to 6V converter to wire 1 & 3 it would be able to supply 6V to my OEM camera? I'm planning to use the converter pictured below.



    Do you really think my European IPA ECU is any different from the American one? I assume they are all produced in Japan..

    Or is there maybe some where else where I could tap power from? Otherwise I'm more than happy to buy a manual from the toyota site.
     
  4. Elektroingenieur

    Elektroingenieur Senior Member

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    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.
     
  5. RVBPRIUS

    RVBPRIUS New Member

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    Alright, but every auxiliary battery in a Prius supplies 12 volt right? And the wires colors and pin location match the US diagram so in my mind it's a pretty safe bet the lightblue and white/black wires are 12volt power to the ECU, agree?

    The reason I'm modifying my Prius is because the standard navigation system (TSN710) was really terrible. The only way to get my OEM camera working with my Android Headunit was to modify the connectors unfortunately.

    Next car is going to be a Tesla Model 3 I'm pretty sure I won't be modifying that one :)

    Edit: Just connected wire 1 & 3 with the converter, and the converter with the power wires from the camera. Still no image.. any suggestions?

    Just to be sure, I used an old RCA video cable as displayed below. The copper wire is suppose to be GROUND and the yellow wire is the video signal right?

     
    #5 RVBPRIUS, Jul 23, 2017
    Last edited: Jul 23, 2017
  6. Elektroingenieur

    Elektroingenieur Senior Member

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    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.
     
  7. RVBPRIUS

    RVBPRIUS New Member

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    Unfortunately I don't have that equipement so I can not troubleshout the wires. I did buy the manuals you mentioned (RM12A6E & EM12A6E.V.1) and found some usefull information.

    This is from the RM12A6E:



    Appearently Toyota changed something with the camera ground wire with European Vehicles after december 2011. Mine is from october 2009. Strangely the color of my ground wire does not match (I have a purple colored wire and in the diagram there is just a stripe ----- for vehicles from before dec. 2011)

    Secondly below is a page from the EM12A6E.V.1



    My theory is that the reason my camera is not getting power is because the OEM satnav is no longer in place, receiving the reverse in signal and sending this to the IPA ECU, since the reverse wire from the L42 connecter (pink wire) is connected to my Android PX5 with use of a scotch lock.

    Do you agree? I'm not too good with car electronics and would really appreciate any help from a professional :)
     
    #7 RVBPRIUS, Jul 24, 2017
    Last edited: Jul 24, 2017
  8. Elektroingenieur

    Elektroingenieur Senior Member

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    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.
     
  9. RVBPRIUS

    RVBPRIUS New Member

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    Ok, so I cut wires 11, 12, 13 and 14 (which are video-, video+, ground and power) from the L64 connector, so now the camera is no longer connected to the IPA ECU. This way I'm sure signals won't interfere. But still no image, I do see a very short 'flicker' before the image turns dark.

    You made a good point about battery drainage. What do you advise? Should I connect my 12volt-6volt converter to wire 3 (GND) and wire 8 (IG) or wire 7 (ACC) instead of wire 1 (BAT) and wire 3 (GRND) to prevent battery drainage?

    I also dug up my old multi-meter. See picture below. Did some trial and error. Found out the power connection is sound, it gives the expected 6.01 volt. How do I test the video signal?



    This is the manual for my multimeter:

     
    #9 RVBPRIUS, Jul 25, 2017
    Last edited: Jul 25, 2017
  10. RVBPRIUS

    RVBPRIUS New Member

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    FINALLY :)



    Turned out the video cable was to blame. Figured this out by connecting a old compact camera which had RCA video out. I also reconnect power to the ACC power circuit in order to avoid battery drainage.

    Thanks for all your help Elektroingenieur (strangely this is a Dutch word)
     
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  11. Elektroingenieur

    Elektroingenieur Senior Member

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    You’re most welcome, and I’m glad to see it’s working.
     
  12. TB46

    TB46 Junior Member

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    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