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Skid sensor alarm, can't accelerate

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by crockettor, Sep 20, 2013.

  1. crockettor

    crockettor Junior Member

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    Oops, try it now.
     
  2. crockettor

    crockettor Junior Member

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    Here's a video of the actual alarm going off.
     
  3. crockettor

    crockettor Junior Member

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    Ok I check the speed sensor resistance and both sides are registering 1.6K ohms.

    I checked both toothed wheels and all teeth are intact, and they appear to be in the same alignment.

    I swapped the sensor from right to left and ran the blink test. ABS blink code read 31 and 32. In removing the right sensor, the 10mm bolt head sheered off, so now I can't put it back on. I couldn't really install the right side sensor correctly on the left side because of the way it's shaped (bumps into the bottom of the joint assembly). So it was plugged in, and mostly installed, but not 100%. It still read a code for the left front.

    Now I put everything back together and it still shows codes 31 and 32 for both front sensors. But maybe that's normal until it clears it later?

    Is there a fuse that relays the sensors I can remove?
     
  4. nh7o

    nh7o Off grid since 1980

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    Your resistance measurements indicate the sensors are OK.

    No fuse, direct connections to the brake controller. I guess clearing codes is something to try. With the same pins shorted as before, with the car in Ready mode press the brakes 8 times in 5 seconds to clear codes.
     
  5. crockettor

    crockettor Junior Member

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    I cleared the codes. ABS 32 reappeared upon starting the next time. Brake still shows 36 and VSC 43.

    I drove the car into work (with the jumper installed, hopefully that's ok!) and ABS codes 31 and 35 began to flash as well. 35 is a new one. After a few minutes on the highway the speedometer stopped working and read zero mph for the rest of the trip. Coming home the speedo worked at low speeds, but cut out again on the highway. Does the speedometer get its reading from the front speed sensors?

    I don't mind buying new sensors if I'm sure that's the problem. But if they still seem to be good, what's the next option?
     
  6. Britprius

    Britprius Senior Member

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    Yes the speedo does get it's information from the wheel sensors.

    John (Britprius)
     
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I suggest that you need to drill out the stud, using an extractor so that you can properly reinstall the RF sensor with a new bolt. Then the fault code associated with that should go away.

    Regarding the LF sensor, I suggest that you should have someone else drive the car while you follow behind in the lane to the left, observing the LF wheel to see if it is wobbling due to a failing hub bearing (resulting from the accident impacting that wheel.) That might be the reason for the LF sensor fault code being logged.
     
  8. crockettor

    crockettor Junior Member

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    Picked up a bolt extractor from harbor freight. Busted 3 drill bits and one extractor. I may be out of my league on that one.

    Wheel bearing seems to pass inspection. There is no noticeable wobble when driving, and when it's up in the air I cannot wiggle the rim in any direction. Everything seems solid. Would it help to have a code reader, or are the blink codes enough?

    What is ABS blink code 35?
     
  9. nh7o

    nh7o Off grid since 1980

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    ABS 35 = "Foreign Object is Attached on Tip of Front Speed Sensor RH"

    When foreign matter adheres to the speed sensor tip or sensor rotor, or the rotor teeth are chipped, these DTCs are output. An abnormal waveform input from the sensor determines these conditions. These DTCs may be detected when a malfunction occurs in the connector terminals or wire harness of the speed sensor circuit.

    Maybe you can look through the hole where the sensor goes and confirm that all the teeth on the rotor are OK as you turn the wheel.
     
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    That 35 code might be caused because the RF sensor is not bolted down.
     
  11. hlunde

    hlunde Member

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    The gap between the speed sensor and toothed wheel is critical. I've have cases (non-Prius, ATE sensor) where just a little bit of debris under the seat of the sensor generated codes. Seat cleaned and all was well.
     
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  12. crockettor

    crockettor Junior Member

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    I took the car to a front end specialty shop to get things checked out. They said everything looked good and loaned me a tap. I made sure the sensor and seat were really clean, got the right wheel sensor bolt tapped out (with about 3 hours of drilling and a dozen busted bits) and the sensor put back with a new bolt. I reset the ABS blink codes. Took the car for a spin. Same problem exists, Skid warning comes on between 35 and 60mph and shuts down the accelerator and even applies the brake. BUT when I put the car in diagnostic the ((!)), ABS, VSC lights flash rapidly and show everything is normal.

    I took the car to the auto parts store and they pulled the codes. They said they wouldn't show anything about the ABS, but that it would show things related to the check engine light (which came on recently).

    P1116 "Refer to vehicle service manual"
    P1150 "A./F sensor circuit range/performance malfunction"
    P1151 "Please refer to vehicle service manual"

    Anyone know more about these codes?
    P1150 makes sense to me, since I bought the car from an auto auction and it had probably sat for 2-3 months. I just barely filled the gas tank, and I only got 29.75mpg on that first tank of gas. I put a fuel additive/cleaner in when I filled up and this second tank seems to be getting much better mileage. I figure the bad gas set off the code.

    So I broke down and took it to the dealership. Went for a test drive with a tech, and as soon as it happened he said "Oh, it's going into limp mode". He said something related to the check engine light could put the car into limp mode. I told him the car has been doing this for longer than the check engine light has been on, but he said the code could have been pending for that time and hadn't set the light off yet. He said it would be $115 for him to check codes and just recommended I get an OBD2 scanner and reset the codes myself to see if the problem comes back.

    As luck would have it, I came home and my Centech 60693 scanner I ordered from Harbor Freight was sitting on my doorstep! So I rechecked the codes and reset them. Took it for a spin. SAME problem with skid control. No warning lights are on, in diagnostic mode everything is flashing rapidly indicated that all systems are ok. Rechecked with the OBD and NO codes have appeared. I'll check for codes again tomorrow, but this all seems very strange.

    Any ideas? Doesn't sound like limp mode to me.
     
  13. ahmeow

    ahmeow Prius Lover

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    You may need to fix/updte the video player software of your computer.
     
  14. crockettor

    crockettor Junior Member

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    The video was mistakenly set to private, but I changed it to public after John posted.
     
  15. crockettor

    crockettor Junior Member

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    After resetting the codes and driving for a few days the skid alert problem still persists. The only code that now shows up on the OBD scanner is P1151. No ABS, Brake, VSC codes. Anyone know P1151?
     
  16. nh7o

    nh7o Off grid since 1980

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    P1151 relates to a problem with the Heat Storage Tank:

    Following conditions are successively met:
    • CHS tank outlet temperature during preheating: below 50°C (122°F) (2 trip detection condition)
    • CHS tank outlet temperature during soaking: 30°C (54°F) or more lower than during coolant recovering
    A first possible cause is due to air in the system after coolant change. The air can get in the tank and must be bled. There are instructions here on PC, if I recall correctly. What did you use to read the codes? If the ABS alert is still on, something is up, and it isn't heat storage tank related.
     
  17. crockettor

    crockettor Junior Member

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    I used a Centech 60693 scan tool from Harbor Freight.
    When I use the jumpers to put the car in diagnostic mode there are no more blink codes showing.
    When I drive in diagnostic mode, everything works fine. However in normal drive mode, when I reach between 35 and 60mph the skid warning starts beeping. Sometimes the car forces a slowdown, sometimes it doesn't. The beeping won't stop until I slow to 25mph.
     
  18. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The DTC P1151 issue is separate from the skid control problem. As previously stated, P1151 may be caused by air in the engine coolant system or a defective coolant tank. The latter is especially likely since the car was hit in the left front while the tank is located in the left front fender well.

    I really think it would be worth $115 for the dealer tech to examine the car and give you a diagnosis and repair estimate. The Centech scanner is useless to retrieve skid control DTC.
     
  19. crockettor

    crockettor Junior Member

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    The coolant storage tank was replaced with the damage, but I suspect the mechanic did not properly bleed the air. It is clearly unrelated to the skid alert.

    I was hoping that someone may have a map of the VSC electrical with specs so I could check the electrical components. I am crossing my fingers that I can find a bad fuse, wire, relay or something that I can replace.

    When I visited the dealer they didn't inspire a whole lot of confidence in their ability to correctly diagnosis. I got the impression they wouldn't really search for the root of the problem and their automatic resolution would be replace the ECU for a couple grand. So I'm looking for any help so I can avoid that fiasco.
     
  20. nh7o

    nh7o Off grid since 1980

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    Here is how to check the harness to see if the speed sensors are connected properly to the Skid Control ECU. You can check the 2 ABS relays, and the 2 MTR relays, but I doubt there is any problem there, as relays rarely fail. Beyond that, you need an oscilloscope to be totally sure that the speed sensor signals are making it to the ECU with proper waveform and amplitude. You can get the speed control pdf from Toyota Tech website that shows how to do that.

    I agree that you need to get a Prius compatible scanner before proceeding much further.
     

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