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2008 dash lights out needs MPX PSC computer part

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by starving student, Dec 21, 2017.

  1. starving student

    starving student New Member

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    I have a 2008 Prius that initially would not recognize the FOB then the dashboard would not light up. It was trouble-shot at the dealer and they told us: "replacement of voltage distribution ecu and diag (found no
    voltage coming out of pin # 35 of voltage distribution ecu, battery voltage in). The part is the MPX P8C #89670-47010. The part new was $1,200 from the dealer. We purchased 3 used parts. After replacing the parts, the dash lit up! BUT...when we hit the brake (to start the car), it appeared to short them all out. The small battery is fine. My son cannot afford another car and we need to try to fix it. Any suggestions would be great for this starving student.
     
    #1 starving student, Dec 21, 2017
  2. dolj

    dolj Senior Member

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    You need to find the source of the short that is blowing up the ECU and fix it, then replace the ECU.
     
    #2 dolj, Dec 21, 2017
  3. starving student

    starving student New Member

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    Any suggestions as to how to narrow it down? We have tried everything that we can think of.
     
    #3 starving student, Dec 21, 2017
  4. dolj

    dolj Senior Member

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    Unfortunately, these things are not always easy. Your best bet is to get the electrical wiring diagram (EWD) and work your way through it.

    The best source of the information is to take a 2 day subscription (US$15) to Toyota Information Services (TIS) where you will find the EWD, troubleshooting guides for DTC and even tutorial information on how to troubleshoot faulty circuits (in the Toyota University section) if you need that.
     
    #4 dolj, Dec 21, 2017
    Last edited: Dec 21, 2017
  5. bisco

    bisco cookie crumbler

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    were there any trouble codes?
     
    #5 bisco, Dec 21, 2017
  6. edthefox5

    edthefox5 Senior Member

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    P8 is the steering ecu.

    I think you mean P6 which is the Power Source Control ECU which turns on relay IG2 which provides 12 volts to the engine ignition. It outputs 12 volts on pin 35 when you push the ready button if the gateway is alive and the immobilizer ecu is cool with fob command. Fuse 60A P/I and Fuse 15A AM2 have to be ok for ignition to happen there. P8 communicates with the gateway and the Hybrid ECU.

    P6 PSC ECU is located right below the combo meter in the dash.
     
    #6 edthefox5, Dec 21, 2017
  7. starving student

    starving student New Member

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    No, but we will try part #3 today and before we hit the brake that kills it we will hook it up to the computer.
     
    #7 starving student, Dec 22, 2017
  8. starving student

    starving student New Member

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    Thanks for the reply! We did purchase the online manual for 2 days and reviewed the diagram that displays the parts you mention. As of last night, after replacing the MPX PSC, the dash lit up (like when you initially start of the vehicle) and then the brake killed it. We will attempt it again tonight with the 3rd and last part and utilize your information. I appreciate your reply.
     
    #8 starving student, Dec 22, 2017
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  9. starving student

    starving student New Member

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    Thanks, we ordered the electrical wiring diagram.
     
    #9 starving student, Dec 22, 2017
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