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Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4373
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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We have a komatsu 250 and are having troubles. It will not

Customer Question

We have a komatsu 250 and are having troubles. It will not more forward or reverse. What do we need to do?
Submitted: 9 months ago.
Category: Construction and Road Equipment
Expert:  Dan replied 9 months ago.

Hi My name is***** is the complete model number and serial number from the ID tag so I know what vintage WA250 you have

Expert:  Dan replied 9 months ago.

Any loud noises when this happened? Transmission oil full and not burnt or discolored? Any metal/debris in the transmission filter?

Customer: replied 9 months ago.
Model#WA250-5. Serial# ***** Product IDentification number KMTWA020C01070341
Komatsu front end loader starts, but it does not move forward or backwards. The brake parking light is on.
No loud noises
Expert:  Dan replied 9 months ago.

Thanks for the info. Check all your fuses and relays.... It sounds like the parking brake not releasing is causing your machine not to move.... This can be electrical or possibly due to low pressure.

Customer: replied 9 months ago.
We already checked the relays and fuse, and pressure is good. No debris in the transmission or discolored in the transmission oil. What else can we do?
Expert:  Dan replied 9 months ago.

The parking brake indicator will not go off on the display panel? If it will not signal the ECU that the park brake is released the transmission will not be allowed to shift

Expert:  Dan replied 9 months ago.

If the park brake indicator was going out and releasing Id say test the shift controller for power in and out in all gear positions....

Expert:  Dan replied 9 months ago.

We need to find out why the parking brake will not release..... Try disconnecting the batteries for 5-10 minutes and resetting the system to see if possibly it is a controller problem needing resetting. If no success there is an actual parking brake issue

Customer: replied 9 months ago.
We did all of that. Where is the valve or switch that sends electricity to the 2 sensors that are located under the hand brake. There is no electricity going there, what can we do to fix that problem?
Customer: replied 9 months ago.
Could you call me at(###) ###-####
Expert:  Dan replied 9 months ago.

Ill send over the additional services offer for you. Also, Click on this link for the parts breakdown for that circuit.

http://komatsupartsbook.com/#?k=!0!12!4619!38!62

Parking brake

Expert:  Dan replied 9 months ago.

Check for power to the clutch solenoid and the harness and connectors for damage

Expert:  Dan replied 9 months ago.

Here is the HST harness diagram. Check the harness and connectors for damage and for power to the solenoids.

http://komatsupartsbook.com/#?k=!0!12!4619!23!32

Expert:  Dan replied 9 months ago.

Test switches 4 and 13 for continuity with an OHM meter in open/closed positions or bypass for test purposes. Let me know

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