Construction and Road Equipment

Construction and road equipment repair questions? Ask a mechanic ASAP

Connect one-on-one with {0} who will answer your question

This answer was rated:

I have a Caterpillar 226, after I start it and release the…

I have a Caterpillar 226...
I have a Caterpillar 226, after I start it and release the park the part light starts to flash. the bucket controls are released and work but the machine will not move? If I move the safety bar up the park light would normally come back to a solid light how ever now it continues to flash. I cannot find anything out about it in the book. CAT00226E5FZ07228
Thanks. Mike
Show More
Show Less
Ask Your Own Construction and Road Equipment Question
Answered in 12 minutes by:
11/7/2014
Mechanic: Dan, Technician replied 7 years ago
Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 14,868
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
Verified

Hi Mike, I will try to help you with this. You will need to check your safety interlock circuit harness and switches as well as the park brake circuit. Here is the procedures.

Solenoid Valve (Parking Brake) Does Not Function Correctly

SMCS - 5479-038-BRK

Top of Form

System Operation Description:

The parking brake solenoid has no diagnostics for checking for faults in the system. The solenoid will NOT be energized when there is an open circuit or a short to ground. If the parking brake solenoid is shorted to the +battery the solenoid will be ON all the time.

Test Step 1. CHECK FOR HYDROSTATIC OPERATION

  1. Occupy the seat.
  1. Lower the armrest.
  1. Turn the key start switch to the ON position.
  1. Press and release the parking brake switch.

Expected Result:

The hydrostatic system should energize.

Results:

  • OK - The hydrostatic system energizes. Proceed to Test Step 2.
  • NOT OK - The hydrostatic system does NOT energize.

Repair: See Troubleshooting, "Switch (Parking Brake)".

Stop.

Test Step 2. CHECK VOLTAGE AT THE SOLENOID VALVE WITH KEY SWITCH OFF

  1. Turn the key start switch to the OFF position.
  1. Locate the parking brake solenoid under the cab.
  1. Disconnect the parking brake solenoid from the electrical connector.
  1. Measure the voltage across the two contacts of the harness connector (A958-WH and 202-BK).

Expected Result:

The voltage should be less than 2 DCV.

Results:

  • OK - The voltage is less than 2 DCV. Proceed to Test Step 3.
  • NOT OK - The voltage is greater than 2 DCV.

Repair: The wire harness is shorted to a + battery circuit. Repair the wire harness or replace the wire harness.

Stop.

Test Step 3. CHECK VOLTAGE AT THE SOLENOID VALVE WITH KEY SWITCH ON

  1. Turn the key start switch to the ON position.
  1. Measure the voltage across the two contacts of the harness connector (A958-WH and 202-BK).

Expected Result:

Voltage should be less than 2 DCV.

Results:

  • OK - The voltage is less than 2 DCV. Proceed to Test Step 4.
  • NOT OK - The voltage is greater than 2 DCV. Proceed to Test Step 6.

Test Step 4. CHECK THE VOLTAGE AT THE SOLENOID VALVE WHILE THE KEY SWITCH IS ON AND THE PARKING BRAKE IS RELEASED

  1. Turn the key start switch to the ON position. Press and release the parking brake switch.

Note: Two people will need to perform this procedure. One person will need to be sitting in the seat with the armrest in the DOWN position.

  1. Measure the voltage across the two contacts of the harness connector (A958-WH and 202-BK).

Expected Result:

The voltage should be greater than 10 DCV.

Results:

  • OK - The voltage is greater than 10 DCV. Proceed to Test Step 5.
  • NOT OK - The voltage is less than 10 DCV. Proceed to Test Step 7.

Test Step 5. CHECK RESISTANCE OF THE SOLENOID

  1. Measure the resistance between the two wires of the parking brake solenoid.

Expected Result:

The resistance should be 10 ± 2 Ohms.

Results:

  • OK - The resistance is 10 ± 2 Ohms.

Repair: The problem does NOT appear to be electrically related.

Stop.

  • NOT OK - The resistance is NOT 10 ± 2 Ohms.

Repair: The solenoid has failed. Replace the solenoid.

Stop.

Test Step 6. CHECK THE WIRE HARNESS FOR A SHORT CIRCUIT

  1. Locate the Interlock ECM.
  1. Disconnect the wire harness.
  1. Turn the key start switch to the ON position.
  1. Check the resistance from contact 13 of the wire harness to the following contacts: contact 1, contact 11, contact 24, contact 29, contact 62 and contact 70.

Expected Result:

The resistances should be above 2 Ohms.

Results:

  • OK - The resistance readings are above 2 Ohms.

Repair: The ECM is unlikely to fail. Terminate this procedure and restart the procedures. Verify all the readings.

Stop.

  • NOT OK - One or more resistance readings are below 2 Ohms.

Repair: The wire harness has failed. Repair the wire harness or replace the wire harness.

Stop.

Test Step 7. CHECK THE WIRE HARNESS FOR CONTINUITY

  1. Turn the key start switch to the OFF position.
  1. Connect a jumper wire between wires A958-WH and 202-BK on the wire harness at the end of the parking brake solenoid.
  1. Locate the Interlock ECM.
  1. Disconnect the wire harness.
  1. Check the resistance between pin 13 and pin 66 of the wire harness.

Expected Result:

The resistance should be less than 2 Ohms.

Results:

  • OK - The resistance is less than 2 Ohms.

Repair: The ECM is very unlikely to have failed. Reconnect all connections and visually inspect the wire harness. Verify that the diagnostic code still exists. If the diagnostic code still exists perform the Test Steps again.Replace the ECM, if the cause of the diagnostic code was not found after the second attempt. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

Stop.

  • NOT OK - The resistance is greater than 2 Ohms.

Repair: The wire harness has failed. Repair the wire harness or replace the wire harness

Hydrostatic System Interlock and Parking Brake Interlock

SMCS - 7630

The interlock system for the hydrostatic system and the parking brake uses the following components:

  • Switch (armrest)

     

  • Switch (seat)

     

  • Switch (parking brake)

     

  • Solenoid valve (hydrostatic pilot)

     

  • Solenoid valve (parking brake)

     

  • Indicator (armrest)

     

  • Indicator (parking brake)

     

When power is applied to the ECM, the outputs for the hydrostatic pilot solenoid and the parking brake solenoid will be off. The outputs will remain off until the ECM receives valid inputs from the armrest switch, the seat switch and the parking brake switch.

When the ECM receives signals that indicate that the seat is occupied and the armrest is lowered, the ECM will turn off the armrest indicator. When the ECM sees the parking brake switch close, the ECM will then turn on the outputs for the hydrostatic pilot solenoid and the parking brake solenoid. Energizing these solenoids allows the machine to move.

Pressing the parking brake switch again will turn off the hydrostatic pilot solenoid and the parking brake solenoid. When the parking brake solenoid is turned off, the parking brake will become engaged and the parking brake indicator will illuminate.

Note: A raised armrest or an unoccupied seat will also cause the ECM to turn off the hydrostatic pilot solenoid and the parking brake solenoid.

Quote:

Switch (Parking Brake)

graphicgraphic
The switch is located on the left headliner to the left of the key start switch.

The switch tells the interlock ECM that the operator wants the parking brake to be applied or released.

The switch is a momentary, normally open rocker switch. When the switch is pressed the circuit closes. This places a grounded input on pin 42 of the ECM.

If the switch is grounded for more than 30 seconds the switch is considered to be stuck in the closed position. The ECM will then flash the parking brake indicator, which indicates a fault.

Note: If the machine is equipped with auxiliary hydraulics, the switch is also seen by the auxiliary hydraulic ECM.

Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 14,868
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
Verified
Dan and 87 other Construction and Road Equipment Specialists are ready to help you
Ask your own question now
Mechanic: Dan, Technician replied 7 years ago

Brake Test

This test will determine if the brakes are functioning correctly. This test will check the solenoid valve ( brake) and the piston motor.

Raise the cab. Refer to Operation and Maintenance Manual, "Cab Support Operation".

graphic

Disconnect electrical connection (1) for brake solenoid (2) .

graphic

Install a 7X-2444 Tee (3) and a 6V-3965 Valved Nipple Assembly (4) in the hydraulic line that runs from the brake solenoid to the piston motors.

Install a 8T-0855 Pressure Gauge to the valved nipple with a 1U-5755 Hose .

Lower the cab. Make sure that the hydraulic line is not pinched.

Sit in the operator's seat and fasten the seat belt. Lower the armrest.

Start the machine. The pressure gauge should read 0. If the gauge does not read 0, inspect the brake solenoid and the voltage for the brake solenoid.

Stop the machine. Raise the cab and reconnect the brake solenoid.

Lower the cab. Sit in the operator's seat and fasten the seat belt. Lower the armrest and start the machine. Set the governor at low idle.

Disengage the parking brake by pressing the parking brake switch. The pressure on the gauge should be 3100 ± 200 kPa (450 ± 30 psi).

If the pressure is not correct, inspect the following items: the brake solenoid, the voltage for the brake solenoid and the brake seal inside the piston motor.

If the brake solenoid is not functioning correctly, replace the solenoid.

When the test is completed, raise the cab and disconnect all gauges and hoses. Lower the cab and bolt the cab in place. Refer to Operation and Maintenance Manual, "Cab Support Operation".

Systems Operation
216, 226, 232 and 242 Skid Steer Loaders Machine Systems

Piston Motor (Hydrostatic)

SMCS - 5058

Top of Form

graphic
View Full Image

Illustration 1

(1) Shaft housing

(2) Rotor housing

(3) Rotor

(4) Piston assembly

(5) Brake housing

(6) Clutch pack

(7) Brake piston

(8) Belleville washer

(9) Roller bearing

(10) Roller bearing

(11) Shaft

The piston motor ( hydrostatic) is of a radial piston type. The piston motor consists of three sections. These sections are the shaft housing (1), the rotor housing (2) and the brake housing (5). Rotor (3) is connected to shaft (11) by splines. Clutch pack (6) is engaged by brake piston (7) and belleville washer (8) when there is no hydraulic pressure. When there is hydraulic pressure, the pressure forces brake piston (7) against belleville washer (8). This allows clutch pack (6) to disengage.


View Image

graphic
View Full Image

Illustration 2

g00816478

(A) Pressure port

(B) Pressure port

(L) Case drain port

(Z) Brake port

 


View Image

graphic
View Full Image

Illustration 3

g00884297

(A) Pressure port

(B) Pressure port

(C) Annular passages

(D) Exposed port

(L) Case drain port

The hydraulic oil from the piston pump flows through ports (A) and (B). One port will be high pressure and the other port will be low pressure. The high pressure port is determined by the desired direction of rotation. For this explanation of the motor, port (A) is considered to be the high pressure port.

Hydraulic oil flows through the axial bore of port A and into the annular passage (C). Hydraulic oil then flows through the exposed ports (D). The exposed ports (D) are below the piston assemblies. As the pressure increases, the piston is forced outward. As the piston is forced outward, the piston rollers roll on the inner diameter of the cam.


View Image

graphic
View Full Image

Illustration 4

g00599046

As the pistons move along the inner diameter of the cam, the pistons turn the rotor. The rotor turns the shaft. The rotor is connected to the shaft by splines. Illustration 4 shows the rotational motion of the pistons as the pistons rotate about the shaft.

As the rotor turns, the previously exposed ports are covered and previously covered ports are exposed. The fully extended piston assembly next passes over an exposed port.

The piston rollers, which follow the inner diameter of the rotor, force the piston assembly toward the shaft. This is due to the shape of the inner diameter of the rotor. The hydraulic oil is forced through the exposed port by the inward motion of the piston assembly. The hydraulic oil then returns to an annular passage (C) which then directs the oil through an axial bore and out of port (B) .

Port (L) is a case drain for oil that leaks by the piston assemblies and for the flushing valve. The flushing valve uses the oil in order to cool the motor. The flushing valve also uses the oil in order to flush harmful particles from the motor.

Oil for the flushing valve flows from the low pressure side of the drive loop. If the oil pressure in the forward drive cavity increases, the pressure increase shifts the spool toward the reverse drive cavity. Oil from the reverse drive cavity flows through the center passage. The oil pressure in the center passage opens the relief poppet. The oil flows through port (L) to the return manifold and the oil is routed through the oil cooler. Then, the oil returns to the tank.

If the oil pressure in the reverse drive cavity increases, the pressure increase shifts the spool toward the forward drive cavity. Oil from the forward drive cavity flows through the center passage. The oil pressure in the center passage opens the relief poppet. The oil flows through port (L) to the return manifold and the oil is routed through the oil cooler. Then, the oil returns to the tank

Ask Your Own Construction and Road Equipment Question
Customer reply replied 7 years ago

Thanks Dan

I have a Mouse in the skid loader. I found where he removed a quick connector. it must have been for the park solenoid.

now the park light stays out when pushed, the bucket hydraulics work, and the left tires work forward and reverse. the right side is locked up tight, can this still be and electrical problem?

Mechanic: Dan, Technician replied 7 years ago

Thanks for the update Mike. It is possible the brake is not releasing on that side or it could be a bad drive motor or gearbox but if there were no symptoms of this before then I would run through the brake test I posted to see if the brake is in fact releasing and the solenoid is functioning. Also check your hydraulic filter for signs of metal/debris that would flag a possible drive motor problem. Take a closer look at the harness as they can cause a lot of damage. Let me know.

Ask Your Own Construction and Road Equipment Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a mechanicLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Dan Your Own Question
Dan
Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 14,868
14,868 Satisfied Customers
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.

Dan is online now

Related Construction and Road Equipment Questions
On a Cat 257b the joysticks don't work correctly after
on a Cat 257b the joysticks don't work correctly after pressing to take out off park. Sometimes one will work then the other after restarting the engine . Both won't work at the same time. Thanks Lloy… read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
Battery light is on and hyrdaulics won't work. Machine will
Battery light is on and hyrdaulics won't work. Machine will move though. 246C Cat … read more
PAPA Chris
PAPA Chris
Field Service Technician
Automotive Technology
44 satisfied customers
Cat 279c will not lift arms or tilt bucket. I have a
cat 279c will not lift arms or tilt bucket. I have a flashing caution light but the book says contact mechanic. i can feel the pump kick in when i push the buttons on the joystick … read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
Le in operation if i hit a bump or jolted. Then sometimes
Le in operation if i hit a bump or jolted. Then sometimes would flicker the lights and beep as if I was turning the key on and off. The battery terminal was loose and I tightened it hoping that was th… read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
I hav problem with CAT 279D it crank but wont start i loose
hi there, i hav problem with CAT 279D it crank but wont start i loose one fuel line the one goes to fuel injector crank the engine there no fuel on the line , but i get the engine runs once but it onl… read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
I have a SVL75-2 and out of nowhere it stopped moving. Lost
I have a SVL75-2 and out of nowhere it stopped moving. Lost all hydraulic control and the red Park light with the hydraulic icon is lit. Motor starts and runs fine. I push the unlock green switch and … read more
Curtis B.
Curtis B.
Technician
Associate Degree
2,324 satisfied customers
753 C no bucket or lift BICS only has seat bar and power
753 C no bucket or lift BICS only has seat bar and power light on. Will spool lock solenoid cause this checked continuity to BICS OK other 2 solenoids click spool lock does not does ha continuity. … read more
Fieldtech59
Fieldtech59
416 satisfied customers
On the 279c caterpillar skid track I have a caution light
On the 279c caterpillar skid track I have a caution light that flashes on the dash that will not go off … read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
The 277b cat skid steer bucket slowed then stopped then
the 277b cat skid steer bucket slowed then stopped then within one minute the drive controls quit, I shut it off checked the fluids gave it a rest then restarted the safety arm light and the park ligh… read more
catmastertech
catmastertech
Field service technician
Vocational, Technical or Trade Scho
1,325 satisfied customers
Case 450ct skidsteer. sit in seat, instrument cluster lights
case 450ct skidsteer. sit in seat, instrument cluster lights up normal, pull lap bar down, start engine, press button to release park, light goes off then comes right back on and at the same time the … read more
Jeremy
Jeremy
Diesel Diagnostic Technician / Expert
Associate Degree
1,511 satisfied customers
I am a New Holland tech, and have gotten involved with a CAT
I am a New Holland tech, and have gotten involved with a CAT 236 skid steer that the RH boom and aux. functions do not work on. I have checked to see that the seat switch and park brake switch both ar… read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
Cat 262 skid loader wiring problem. Parking brake does not
cat 262 skid loader wiring problem. Parking brake does not appear to release. Light on steady. Motor starts. No hydralics for wheels or bucket. Repaired several mouse chewed up wires behind cab in wir… read more
Jeremy
Jeremy
Diesel Diagnostic Technician / Expert
Associate Degree
1,511 satisfied customers
My bucket control stopped functioning on my 279c skid steer
My bucket control stopped functioning on my 279c skid steer today. I have track control but no bucket. It has been acting funny lately but today it quit all together.… read more
Bradley Martin
Bradley Martin
77 satisfied customers
i have a 2003 2054 mustang skid steer. the parking brake wont
i have a 2003 2054 mustang skid steer. the parking brake wont release sometimes and the hydraulics quit sometimes. what to check?… read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
242B3 bucket and boom hydraulics won't engage but the 4in1
242B3 bucket and boom hydraulics won't engage but the 4in1 clamp and drive still works? any ideas, a switch or somthing else?… read more
catmastertech
catmastertech
Field service technician
Vocational, Technical or Trade Scho
1,325 satisfied customers
I have a bobcat s250 with error code V7401, can some one explain
I have a bobcat s250 with error code V7401, can some one explain this code , my bucket locks out when ever it wants , with bucket light flashing , I have not had it happen to me , but the customer has… read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
Cat 277 multi terrain loader (CAT 00277JCNCO2380) bucket controls
Cat 277 multi terrain loader (CAT 00277JCNCO2380) bucket controls are not working at all. The travel or tracks will engage but not bucket operations… read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
I have a Bobcat 873 skid steer. When I start it the top and
I have a Bobcat 873 skid steer. When I start it the top and botXXXXX XXXXXghts on the Bobcat Interlock Control System come on as normal.(top light-system activated, botXXXXX XXXXXght is power.) After … read more
Dan
Dan
Technician
Auto Mechanics 1&2/diesel mech
14,868 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

He answered my question promptly and gave me accurate, detailed information. If all of your experts are half as good, you have a great thing going here.

DianeDallas, TX

< Previous | Next >

Meet the Experts:

Curtis B.

Curtis B.

Technician

2,324 satisfied customers

Technican turned service manager with multiple lines of equipment and rental units.

Wayne

Wayne

Journeyman

1,298 satisfied customers

worked on many road graders, Bull dozers , skid steers, Rollers

Cat Man

Cat Man

Cat Engine Expert

578 satisfied customers

I am ASE Master Certified.

dieseldan55

dieseldan55

Mechanic

299 satisfied customers

Road Mechanic for Volvo Construction Equipment.

Chris (aka- Moose)

Chris (aka- Moose)

Technician

85 satisfied customers

24 years of experience diagnosing & repairing

Steve

Steve

Mechanic

42 satisfied customers

Heavy Equipment Mechanic for 25 years

JBFixxer

JBFixxer

Mechanic

22 satisfied customers

16+ years experience, hydraulics,hydrostatics, engines, fuel injection systems. And everything in between.

< Previous | Next >

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x