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Case 621B brake pressure light

Discussion in 'Wheel Loaders' started by Rayburn, Jan 5, 2017.

  1. Rayburn

    Rayburn New Member

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    Jan 5, 2017
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    Location:
    Mantua,Ohio
    Brake pressure light and alarm are on. Everything is operating normally. Brakes and trans working fine. Is there any way to disable this light and alarm temporarily until I can get the machine home to the a warm garage?
     
  2. Vetech63

    Vetech63 Senior Member

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    2,068
    Location:
    Oklahoma
    You could pull a fuse from the panel but you may lose all your gauges or something else. It depends on what is fed through that fuse.
     
  3. quackattak

    quackattak Well-Known Member

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    Location:
    Oregon
    Your buzzer is part of control panel, I can't remember for sure where the Pressure sender is. I think it's close to brake accumulator.
     
  4. Rayburn

    Rayburn New Member

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    Location:
    Mantua,Ohio
    Case 621 B brake pressure light

    Is there a relay that can be jumped? Don't want to lose my other sensors.
     
  5. quackattak

    quackattak Well-Known Member

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    No, I'm going off long term memory. I'm pretty sure there is a small pump on front of engine, this runs your brake system. Follow the small line under cab and you should find sender. Unplug sender & try a jump wire.
     
  6. brianscathouse

    brianscathouse Well-Known Member

    Joined:
    Oct 30, 2012
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    Occupation:
    Auto repair shop owner/mechanic
    Location:
    Nelson, BC, Canada
    Noticed fresh thread about brakes on these units and have same issue and have narrowed issue to brake accumulator valve. Pump tests good but only 500 psi pressure at valve with system intact. Took valve apart and some wear on spool valve and 0-rings worn no scoring. Worth resealing or put in new valve? Got quoted here in Canada 521$ for a seal kit. New Valve is 2000$. Anyone know if any better deal anywhere else?
     
  7. Rayburn

    Rayburn New Member

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    Location:
    Mantua,Ohio
    Does anyone know where the brake pressure switch is located for sure?
     
  8. brianscathouse

    brianscathouse Well-Known Member

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    Occupation:
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    Located on valve just after and below pump on frame. Just had mine apart yesterday. Same location as test ports for the system.
     
  9. brianscathouse

    brianscathouse Well-Known Member

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    Occupation:
    Auto repair shop owner/mechanic
    Location:
    Nelson, BC, Canada
    BTW ordered seal kit for mine after I found out it includes spool valves, poppets and all seals with upgraded parts from Case. Everything except main body and plugs.
     
  10. backhoe1

    backhoe1 Well-Known Member

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    Aug 24, 2007
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    93
    Location:
    South Dakota
    I had a 621B with the brake light and buzzer on constantly. After the dealer replaced brake valve and brake pump it was still on most of the time. I called to complain about it and the mechanic told me to unplug the sensor if it bothered me that bad. He described where the sensor was and when I located it, the sensor had fluid running out through the wire end. I replaced the sensor and it worked perfect. $4000 to the dealer and still got to fix it myself with a $70 part. To answer your question the sensor should be on the right side under/behind the cab close to the test couplers.
     
  11. brianscathouse

    brianscathouse Well-Known Member

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    Occupation:
    Auto repair shop owner/mechanic
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    Got and installed kit and it didn't come with spools but replacing all the o-rings and seals and poppets did fix my pressure light and brake issues. Now I still have to get trans to work properly. Very erratic operation. Wont always go into gear and when it does it slips sometimes and others locks right up with no issue. Seems like electrical issue. Doing more diagnosing today. Is it possible to damage trans by trying to work it with low brake pressure due to the safety systems built in for it. Previous owner kept using it even with trans working erratic. Oil is full and looks in good condition. Going to remove filter and cut apart to see if any bad things inside. Trans acts strange in that if you sometimes hit left pedal it will shift ok. Sometimes working shifter through gears makes it work. Never works for very long and trans temp started to get hot when we kept trying as if converter was slipping. If it goes into gear fully you can pass a stall test tho.
     
  12. GaryHoff

    GaryHoff Senior Member

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    Feb 26, 2009
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    Occupation:
    Heavey Equipment Mechanic
    Location:
    Alberta, Canada
    Low brake pressure will cut out first and second gear.
    Failed speed sensor will cut out third and fourth gear.
    I would recommend checking your transmission pressure. You may be slipping the clutches. Look for black material in the bottom of the transmission oil or in the filters.
    Also the clutch cut out switch is on the left brake pedal. Check that for corrosion or dirt or sticking.
     
    Last edited: Jan 19, 2017
  13. brianscathouse

    brianscathouse Well-Known Member

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    Occupation:
    Auto repair shop owner/mechanic
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    Tested speed sensor and reads low against specs. 1000 ohms cold or hot while spec in manual says 1800-2100 normal temp but 1100 ice cold. Pulled sensor and found it was shimmed wrong and end worn into. Will get a new one and retry. Pulled and cut apart filter and all clean inside. Installed new one. Would speed sensor.resistance.affect initial engagement of trans?
     
  14. GaryHoff

    GaryHoff Senior Member

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    It is difficult to get a proper shim reading without the tool. Make yourself a tool. Its just a piece of round stock, with a snap ring on it. Push the tool into the hole, and it will slide the snap ring up, the tool will hit the gear, and that will tell you your depth. The resistance of the speed sensor never seems to match when I check them either. I don't believe that a bad speed sensor would affect your initial transmission engagement.

    There is very little gap between the sensor and the gear. The transmission bearings may be worn, allowing the gear to touch the sensor.
     
    Last edited: Jan 19, 2017
  15. brianscathouse

    brianscathouse Well-Known Member

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    Occupation:
    Auto repair shop owner/mechanic
    Location:
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    Did some more checks and found resistance from computer plug in to solenoid 4 was out by 40 ohms. Pulled cover off to check solenoids and by wiggling the plugins and seating it properly the reading came into spec (all matching). Will re-assemble and retry tomorrow. If that doesnt fix it.at least I have eliminated all the electrical and brake issues that may have caused the trans to fail in the first place.
     
  16. GaryHoff

    GaryHoff Senior Member

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    ok. That may be part of your issue. If you had a solenoid issue, you should only have transmission problems in certain gears. Try swapping solenoids around. Refer to shift logic chart.
     
  17. brianscathouse

    brianscathouse Well-Known Member

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    Occupation:
    Auto repair shop owner/mechanic
    Location:
    Nelson, BC, Canada
    Working ok in lower gears now but 4th will occasionally kick out. I think all I have left is to replace damaged speed sensor. Thanks for all your help.
     
  18. fwhitesides

    fwhitesides New Member

    Joined:
    May 14, 2019
    Messages:
    2
    Location:
    ketchikan, alaska
    have a 821 B loader with 5000 hours, just bought it. developed a issue first 50 hours where it sometimes does not move, and then it was only shift in 1st and 2nd gear, today the brake pressure light is blinking , I just ordered filters for the machine and going to service it when they come, any ideas on what might be happening with it ? tried to figure out how to start a thread and wasn`t no luck so trying this , thanks for any help you might give