1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Power Steering Problem

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Metalneck Greg, Jun 26, 2018.

  1. Metalneck Greg

    Metalneck Greg New Member

    Joined:
    Jun 26, 2018
    5
    0
    0
    Location:
    Tenino WA
    Vehicle:
    2007 Prius
    Model:
    Touring
    I have been finding good info on this site since I bought my Prius so now I've joined. I have a 2007 Prius with no power steering. Code is C 1554. I replaced the EMPS ECU with a used one from Ebay. That didn't fix it. I checked the fuses in the engine compartment fuse box. Everything else works. I couldn't find info on the location of the EMPS relay or how to test it. Can someone help
     
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    welcome!

    have you looked in the service manual?
     
    Raytheeagle likes this.
  3. Metalneck Greg

    Metalneck Greg New Member

    Joined:
    Jun 26, 2018
    5
    0
    0
    Location:
    Tenino WA
    Vehicle:
    2007 Prius
    Model:
    Touring
    Thank you. I haven't. What manual are you talking about? Is it online?
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,198
    6,461
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    By EMPS, I assume you meant the power steering ECU. If that is not what you meant, you replaced the wrong ECU.

    DTC C1554 indicates a power supply relay failure. Check the 50A EPS fuse (which is part of the fusible link assembly - the 5" long white and clear plastic box within the main relay/fuse box next to the inverter) and the PIG power source circuit which connects the EPS fuse to the power steering ECU. The relay is part of the power steering ECU.

    You can obtain the factory electrical wiring diagram and repair manual info at techinfo.toyota.com
     
    SFO likes this.
  5. Metalneck Greg

    Metalneck Greg New Member

    Joined:
    Jun 26, 2018
    5
    0
    0
    Location:
    Tenino WA
    Vehicle:
    2007 Prius
    Model:
    Touring
    Thanks for your response. This is very helpful. All of the links look good. I checked the PIG connection on the EPS ECU (big white wire). There is no voltage there. Is that what you meant when you said to check the PIG power source circuit? There is power at the IG connection (little black wire that also comes from the Power Source System). PriusChat has a downloadable 2004 wiring diagram although parts are missing
     
  6. Metalneck Greg

    Metalneck Greg New Member

    Joined:
    Jun 26, 2018
    5
    0
    0
    Location:
    Tenino WA
    Vehicle:
    2007 Prius
    Model:
    Touring
    Thank so much. You lead me right to the problem. All the links looked good but when I pulled the cover off and tested each link the bottom right one was bad. I will replace the fusible link but is there something else I should look for?
     
  7. Dxta

    Dxta Senior Member

    Joined:
    Nov 7, 2016
    1,932
    766
    0
    Location:
    Lagos
    Vehicle:
    2008 Prius
    Model:
    II
    Just like @Patric has said, locate the fuse at the engine side.
    If you're capable, look through the clear through fuse. If any of them are melted, you know you got to replace the fuse. Its kinda hard to remove though. If after checking the fuse its intact, you got to get a digital voltmeter to test for power.
    There might be a possibility that there's a short circuit problem somewhere on your EPS circuit.
     
  8. Metalneck Greg

    Metalneck Greg New Member

    Joined:
    Jun 26, 2018
    5
    0
    0
    Location:
    Tenino WA
    Vehicle:
    2007 Prius
    Model:
    Touring
    Thanks for the help everyone, Patrick, I have seen a lot of helpful comments from you all over this site - your awesome, dude. My power steering works great now. I love my Prius! I think it is a very well designed car. I used to laugh at Prius drivers because I just didn't realize how cool they are.
     
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,198
    6,461
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    The next question is, why did the fusible link blow? Measure resistance from the PIG wire to body ground. If the resistance is very low that would imply the issue which blew the fusible link is still present.
     
    SFO likes this.