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Warning Lights, Stop-Light Switch, ECU, and more...

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by aberns, Jul 20, 2015.

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  1. aberns

    aberns Junior Member

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    2004 Prius with 170,000+ miles.

    A couple months ago, the BRAKE, tire pressure, ABS, VSC lights all came on as I was driving (I was slowing down with the brakes). The car continued to drive just fine. I drove it straight to Luscious Garage (a great hybrid-only shop in San Francisco) and the only error that was recorded was with the stop-light switch. However, the switch works fine, as evidenced by the fact that the brakes consistently trigger the lights. The mechanics reset the lights and the error message and told me to come in if it happened again.

    About a month later, it happened again. Again as I was slowing down with the brakes. I took it back and, again, they saw the stop-light switch error and nothing else. After some research, they told me that it could very well be my ECU malfunctioning and that I might need to replace it. They also offered to replace the stop-light switch, as there could possibly be a problem with the part of the circuit that reports back to the ECU, rather than the first part, which simply switches the brake lights on. Obviously, I opted for the replacement switch, which was a $100 repair, as opposed to the near $2000 replacement of the ECU.

    It has been about a week and I haven't gotten the warning lights again, but I fear that I will. In addition, my cruise control has not worked for about a year, and many things have been tried to no avail, e.g. replacement cruise control switch, replaced fuses, battery check, and probably some I am forgetting about. The remaining possibilities were expressed to me to be the clock spring and the ECU, both of which are relatively expensive. However, this saga with the warning lights leads me to believe that the ECU is the likely culprit.

    I know I should just wait until (or if) I get the warning lights again, but I am driving across the country soon and would really like my cruise control. Am I assessing the situation properly? Is my ECU likely going bad? Does anyone have experience with problems like this? Any guidance would be appreciated. Thank you!
     
    #1 aberns, Jul 20, 2015
  2. bisco

    bisco cookie crumbler

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    welcome! it will be interesting to see if anyone here can top luscious garage. all the best!(y)
     
    #2 bisco, Jul 20, 2015
  3. ericbecky

    ericbecky Hybrid Battery Hero

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    Seriously, you can't do any better than Luscious Garage.
    They know their stuff.
     
    #3 ericbecky, Jul 20, 2015
  4. Avi's Advanced Automotive

    Avi's Advanced Automotive Independent hybrid repair shop

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    The problem isn't coming back, trust me!

    The switch is two switches in one. The part that turns the brake lights on can work fine while the part that tells the skid control ECU what's going on can. ;-)
     
    #4 Avi's Advanced Automotive, Jul 20, 2015
    bisco likes this.
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It sounds like the one problem is resolved. This problem involved the skid control ECU.

    The cruise control functionality comes from the hybrid vehicle ECU (which is a different ECU.) Did you mention to Luscious Garage that the cruise control was not working? If they suggested that the clock spring needs to be changed, then I would certainly accept their suggestion.
     
    #5 Patrick Wong, Jul 20, 2015
  6. khoda355

    khoda355 Junior Member

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    I have this same problem... I changed the stop light switch already and it still is giving me that same code... Ecu?
     
    #6 khoda355, Dec 5, 2015
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. Exactly what code?
    2. ECU: electronic control unit
     
    #7 Patrick Wong, Dec 5, 2015
  8. khoda355

    khoda355 Junior Member

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    I already fixed the orange plug code
     

    Attached Files:

    #8 khoda355, Dec 5, 2015
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

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    C0210: check the right rear wheel speed sensor and the associated wiring harness. Also, check the tire air pressure at all four tires especially the right rear. Spec is 35/33 psi; I use 44/42 psi. Make sure you do not have any problems with tire pressure.

    C1249: do the brake lights work when you depress the pedal?
     
    #9 Patrick Wong, Dec 6, 2015
  10. khoda355

    khoda355 Junior Member

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    Brake lights to work. Also should state that the BRAKE ebrake light is on even with the ebrake off. Psi is a little low, all the way around its at 30, will fill that up but I don't think that's the problem but would be very nice if it was!

    I will check The speed sensor.. Thinking of just swapping it to the other side and see if the problem will go with it.

    Thank you for you're help! Will report back tomorrow mid day!

    Is this the speed sensor ?
     

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    #10 khoda355, Dec 6, 2015
  11. khoda355

    khoda355 Junior Member

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    Really don't get it.. Tires filled up... And I cleaned the wire for the speed sensor and still have the lights on.
     
    #11 khoda355, Dec 6, 2015
  12. khoda355

    khoda355 Junior Member

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    The thing is it won't pick up any speeds of the wheels on the techstream...

    And now I see the c1313 code could that be doing this all?
     

    Attached Files:

    #12 khoda355, Dec 6, 2015
  13. Patrick Wong

    Patrick Wong DIY Enthusiast

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    C1313: Check the ABS #2 relay. If the skid control ECU is not getting reliable 12V power, that is not going to help.
     
    #13 Patrick Wong, Dec 6, 2015
  14. khoda355

    khoda355 Junior Member

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    Just swapped them out with another 2007 Prius still same problem I'm having didn't change..
     
    #14 khoda355, Dec 6, 2015
  15. khoda355

    khoda355 Junior Member

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    I went in the DTC and I guess I found more fault codes.
     

    Attached Files:

    #15 khoda355, Dec 6, 2015
  16. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Maybe the time has come to swap the skid control ECU if you can get to it in the dashboard.
     
    #16 Patrick Wong, Dec 6, 2015
  17. khoda355

    khoda355 Junior Member

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    Is it just about taking the dash all apart?
     
    #17 khoda355, Dec 6, 2015
  18. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, subscribe to techinfo.toyota.com for detailed info about how to do that. The skid control ECU is near the steering column.

    Also, make sure the 12V battery is in good shape before you go to the trouble of disassembling the dashboard. You don't want to ignore a really easy fix - if the battery happens to be marginal.
     
    #18 Patrick Wong, Dec 6, 2015
  19. khoda355

    khoda355 Junior Member

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    Great thank you.

    Do you think that will be the solution or should I run some tests to figure out anything else that can be the problem?
     
    #19 khoda355, Dec 6, 2015
  20. khoda355

    khoda355 Junior Member

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    With car off its at 12.6 on the vehicle signal check
    Car on its at 14.3

    Sounds about right?
     
    #20 khoda355, Dec 6, 2015
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