2000 LX470 issues - weird mechanic diagnosis

Discussion in '100-Series Cruisers' started by riffman12, Dec 6, 2018 at 12:09 AM.

  1. riffman12

    riffman12

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    Hey guys - sorry for the long read here but I'm a little stumped.

    I bought my 2000 LX470 about a year ago with 213k on the clock. I'm now at 222k. It's fairly stock other than 33" Cooper ST Maxx and a Trail Tailor rack / Tepui tent. Here's a pic of a recent trip:

    [​IMG]

    Maintenance I've done in my ownership:
    - inspected and re-torqued front wheel bearings
    - replaced entire master cylinder / booster assembly with a new OEM unit
    - Oil, filters, etc.

    It's been an amazing vehicle and super reliable, other than a few recent quirks:

    1) Ever since replacing the Master Cylinder, I'm getting a strange inconsistent brake pedal. 80% of the mornings I get in the car, the brake pedal feels great. The other 20% of mornings, the pedal starts to get firm way further down in the stroke. In fact, it seems to be at a slightly different spot every morning - like today it was very high up. It always stops fine, just doesn't feel very nice when the pedal is really low. There is no loss of fluid and the pump runs for the correct amount of time on startup. No warning lights or alarms since replacing the MC.

    2) For the last 10-20 feet before coming to a complete stop there is a very slow wobble felt through the car. Almost as if i'm slowly lifting a bit, braking a bit, lifting, braking, lifting, braking all the way until I stop. I'd estimate it's about a 1 second wobble if that makes sense. I do not feel anything through the steering wheel. It does not vibrate or anything at higher speeds. Seems to only do it under gently braking.

    3) on a couple of occasions, I have had a loss in power going up a hill. Feels like I suddenly lifted my foot off the gas even though it's held at the same spot. Revs do not jump at all. fixes itself in about 15 seconds or so. I'm thinking this might be the APPs that I have read about. Weird thing is it's only really happened on 2 or 3 occasions in 6 months. Very rare.



    Now here's the weird part, I took it to a local shop I trust to figure these things out, and I pointed to the idea of the pedal sensor and maybe bleeding the brakes for the inconsistent brake pedal.

    However, the tech road tested it while watching live data and saw that the Left Rear wheel speed sensor was giving weird (7-8 digit) readings at any speed while the other sensors read fine. He removed the sensor and cleaned it. Tested the resistance and it's within spec.

    he thinks that this sensor is somehow relaying weird information which is engaging the ABS making the brake wobble, and occasionally cutting throttle.


    I haven't ever read about a wheel sensor causing issues like this. Also, the sensation I'm getting while braking is nothing like the speed of ABS engagement, more of a very slow wobble.

    In the end the shop kind of gave up and recommended possibly taking it to a dealer who has more sophisticated scanning tools.


    Sorry for the long read, but what do you guys think? Should I go down this wheel speed sensor route? Or look at something else?
     
  2. Blackbirdaerial

    Blackbirdaerial

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    2) might be the ABS sensor. Mine did something similar because it would not read under 7mph. So when coming a stop I would watch my wheel senor reading 9,8,7, 0mph. ABS would modulate everytime for about a second coming to a stop (at 7 mph). Changing the sensor eliminated all the symptoms.
     
  3. nissanh

    nissanh

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    Also check the front wheel bearings for play. When front rotor wobbles, brake padle acts weird.
     
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  4. riffman12

    riffman12

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    Interesting. Is that the same as what my tech is calling a speed sensor? Are the rears easy to replace? Have a part number by chance?

    Hm ok I'll double check those. Thanks
     
  5. nissanh

    nissanh

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    There is only one sensor per wheel and some call it speed sensor and some call it ABS sensor.
    Google Camelbacktoyota parts and then select your car/year and electrical. Look for the brake diagram
     
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