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Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 5186
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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I'm checking a 99 case 621c loader that been driving and

Customer Question

I am Martin
I'm checking a 99 case 621c loader that been driving and after some time of worki, it stop and it just gets like in neutral, the problem is getting worse because is doing it more often now
But engine continue running and all the other hydraulic system's respond but not forward or reverse at all
After engine is turned off and cranked again it drive ok onto next episode happens!
The only light at the control panel is the brake light all times
And when putting in gear the triangular red light started to show
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  Dan replied 1 year ago.

Hi Martin, My name is***** will be glad to help. From your description it sounds like the park brake is not releasing to allow forward and reverse travel. Check and verify the park brake is releasing. Also another thing to check is the neutralizer circuit that disengages the transmission when the left brake pedal is pressed or the button on the control lever is pushed if equipped on the bucket controls. If equipped with that option check the wiring from the joystick for damage. Check for power in and out of the shift controller in each gear position and to the transmission solenoids. Check the transmission filter and oil for metal/debris indicating internal mechanical problems as well as burnt or discoloration of the oil. Let me know

Customer: replied 1 year ago.
I'm sorry
The rain and weather didn't allow me to check the general information that you sent me
I will check it sometime this week!
Have a great weekend!
Expert:  Dan replied 1 year ago.

thanks for the update. Keep me posted and let me know the results and if we need to dig deeper into this.

Customer: replied 1 year ago.
Hi Dan Im back with this head ache!
The parking brake was disabled!
Because the caliper was leaking, someone removed the line from the caliper and plugged it!
I installed New brake caliper and a brake line, but I'm not getting oil pressure when I push the park break button switch ( park break is electric) first time I see a case machine
How is the process to bleed the park break caliper in this tractor?
How the park break switch work
There are four terminal in the electric connector
1) One terminal with 2 orange 19A wires with power when the ignition switch is turned on
2) a yellow wire that receive power when the park switch is turned on
3) a black with ground permanent wire
4) one terminal with 2 silver wires that I don't know what is for?
Transmission fluid look good and healthy
Replace the transmission filter and I found not dirt or debris on it
The tractor drive, like in second gear and show the 2nd gear at the instrument panel, suddenly the tractor lose the gear and show the N of neutral in the instrument screen
If turned off the engine, and cranked again, the tractor started driving nicely forward or backward again onto next episode happens!
I don't know where the solenoid go in this tractor!
I saw something that looks like a valve body but not visible solenoid's
I will appreciate you help
Thanks and have a great day!
Expert:  Dan replied 1 year ago.


Make sure the machine has come to a complete stop before applying the parking brake.

Push down on the top of the park brake switch to ENGAGE the parking brake.


The Parking Brake is a spring applied, hydraulic released brake. When the key switch is turned to the OFF position or the brake system loses pressure the Park Brake will engage. Always wear your seat belt when operating.


The service brake must be at operating pressure before the parking brake can be released. The Brake Pressure Indicator Lamp must


be illuminated when disengaging the parking brake. See Parking Brake in Operating Instructions in this manual.

Push down on the bottom of the parking brake switch, hold pressure on the brake pedals and put the transmission control lever either in FORWARD or REVERSE to DISENGAGE the parking brake

Expert:  Dan replied 1 year ago.

1.To release the park brake, all the following are required: A.Push the Park Brake switch to the release position. B.Service brake depressed indicating brake lights. C.Transmission shifter positioned from N to F or R for a second,and back to N. D.Adequate service brake pressure to stop the machine.

2.To engage the park brake, any of the following is required: A.Loss of service brake pressure in both axles. B.Loss of system electrical power (key OFF). C.Park Brake switch in engaged position.

3.To test these functions: A.Start on a clear level surface B.With Step 1, A through Ccomplete, start the engine release the park brake, red warning light out.C.Shutdown the engine turn the key switch to the ON position,engine off the Park Brake light should come ON.D.Release the park Brake using Band C in Step 1. Make sure the park brake light is out.E.Pump the service brakes, the red warning light should come ON first. Continue to pump the service brakes. Pump until the brake light comes ON, pump the brakes three more times, it could require as many as forty pumps total.F.Start the engine and allow the brake pressure to build until the warning light goes out.G.Depress the service brake and release. The light must stay ON.H.Put the transmission in F or Rand back to N the brake light must stay ON.I.Put the park brake switch in the engaged position, attempt B and C in Step 1. The park brake light must stay ON.

Expert:  Dan replied 1 year ago.

4.Put the park brake switch in the release position, attempt B and C in Step 1. The park brake light must turn OFF, A.Allow the machine to roll slowly forward with the transmission in F put the park switch to engage.The machine must come to a stop immediately. Park light ON.Transmission disengages.If all steps are working positive the system works correct. If there was a problem with the test contact your dealer

Customer: replied 1 year ago.
Hi Dan!
I really appreciate you help, but I think that we need go a little deep
The instructions to operate the parking brake are good but I need to know what happens in the system when the parking brake is applied!
1) What happened when the switch is pressed to apply the park brake!
What the 4 wires signals come or where the signals going?
2) If the oil pressure is constantly at the break caliper or just get there one time when the brake is applied?
3) What is the pressure amount that should show when checking pressure?
4) if can i check any especific pressure reading in any place when the machine jump to neutral by itself?
5) Where the transmission solenoid's are located in this machine and what reading in Volt's should I get in the electrical connections torch the solenoid's and when?
Expert:  Dan replied 1 year ago.

Hi Martin,

1. Power goes to energize the park brake solenoid valve to open the valve to send oil to the caliper to release the parking brake. When the brake is applied the pressure is removed and spring tension takes over to hold the brake applied.

2. Answered in #1 and my initial post. It is spring applied..... pressure released

3. I do not have this spec readily available but it will be likely 350- 550 PSI

4 and 5. Please give me the full information from the transmission ID tag as this information will need to come from the transmission manual.

Expert:  Dan replied 1 year ago.

Hi, Did you get this resolved?

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