• Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

Cat 277B Aux hydraulic does not work

M

Mark250

Senior Member
that's all I can think of. if moving the thumb wheel doesn't change the duty cycle signal it appears to be faulty. as lantraxco suggested earlier its possible the rocker is not moving out of the dead band (cantered position)
Mark
 
I

Iggys6

Well-Known Member
Mark250 said:
that's all I can think of. if moving the thumb wheel doesn't change the duty cycle signal it appears to be faulty. as lantraxco suggested earlier its possible the rocker is not moving out of the dead band (cantered position)
Mark
Click to expand...

OK thanks mark! I will let you know today how it goes when the part comes. Thanks again
 
I

Iggys6

Well-Known Member
Mark250 said:
that's all I can think of. if moving the thumb wheel doesn't change the duty cycle signal it appears to be faulty. as lantraxco suggested earlier its possible the rocker is not moving out of the dead band (cantered position)
Mark
Click to expand...

I got the new joystick today and changed it over and it works great now. Thanks!! :)
 
C

craig Monroe

Member
I followed one of your threads regarding a skidsteer with hydraulic issues. I have a 2003 cat 277b. The machine is working well and the arms and all other hydraulics are working fine. The implement hydraulics however do not. they will intermittently work at best in one or both directions from the thumb roller. I did the following from your thread:


1/ lift the cab hook a LED test light across one of the aux solenoid coils with enough lead to reach the in to the cab with the back in its lowered position operate the machine and check the status of the test light if it comes on while operating the machine yo may have an hydraulic problem
(did not come on)

2/ gain access to the 12 in connector for the RH joystick and check that you have power between pin 1 (8 vdc) and pin 2 ground return. if no power you need to check that the ECM battery voltage between pins 1 and 3 at the ECM.if no power at the ECM you have a possible harness problem which will need to be addressed.
(had the voltage)

3 /If all this is ok, next check that you have a signal coming out of pin 3 at the 12 pin connector (check with multimeter set on duty cycle setting and connected to pins 2 and 3) while moving the joystick you should have a varying duty cycle reading.
(results were 50%-53%)

4/ if that is ok you need to check the duty cycle output from the ECM between pins 42 and 58 and 42 and 40 .
(1.4% with no buttons pressed is this normal?)

5/ if ok check the duty cycle at the control valve aux solenoid coils using extension test leads that will reach in to the cab
6 if this is ok check the resistance of the control valve aux solenoid coils
(the front solenoid coil nearest the front of the machine without pressing roller button 66.6hz,.6% duty cycle, and 61% with button pressed(note: this time when i pressed the button it worked but stopped working shortly after). The back solenoid coil i checked and it read 590HZ,1.4% with and without pressing the roller button.)

note: the roller button has over the course of the last week or two worked spontaneously both rolling forward and back


this is as far as i got with your list of items to check. what are your thoughts? thank you for your time in advanced


if there is no output at the ECM and you are positive that you have good power and good earths there iis only one thing lef to do before condemning the ECM and that is to try to reflash the ECM unfortunately unless you have a dealer version of ET you cant do it your self
have included an electrical schematic
if you need additional info please ask
 
M

Mark250

Senior Member
craig Monroe said:
3 /If all this is ok, next check that you have a signal coming out of pin 3 at the 12 pin connector (check with multimeter set on duty cycle setting and connected to pins 2 and 3) while moving the joystick you should have a varying duty cycle reading.
(results were 50%-53%)
Click to expand...
Hi looking at this I have a typo that may have confused you. where it states to move the joystick should be move the rocker switch backwoods and forwards
upload_2019-8-25_8-51-14.png
see how you go and let me know
Mark
 
M

Mark250

Senior Member
In that case I would recheck your work to make sure of the electrical side and then see if the actual roller wheel is moving the switch. if it is you have a bad rocker assembly
mark
 
C

craig Monroe

Member
So just to confirm you want me to check the duty cycle across pins 2 and 3 on the plug that goes to the rh joystick thumb wheel while moving the thumb wheel forward and back?
 
Last edited:
C

craig Monroe

Member
I tested it again and it started at about 50% then jumped to 80% and down to 20%. the wheel worked in one direction. Then the wheel stopped working all together. Then the reading stayed at about 50%. I figured it would be the handle, so i replaced the handle. With the new handle installed the roller wheel will work in the forward position every-time without issue. (the 4-5 startup and stops i tried it on)However nothing in the back position. I went to test between pins 2-3 like i did previously however i am having trouble getting a reading due to the new plug being smaller. Previously i was able to stick probing needles in but now i can not get connectivity that way. Do you have a suggestion of how to obtain contact without stripping the wire? Another new thing once the new handle went on i am getting the light on the right side top and center lighting up. It does not stay fully lit rather it it strobes with different intensities. I believe it is the interlock override light. I am not sure what this all means, i was hoping you could help.
 
M

Mark250

Senior Member
Hi, Cat have a 7x1710 probe group that inserts in the rear of the connector and are a must for troubleshooting in my opinion
Have you verified you are getting 8 Volt supply to roller
Mark
 
C

craig Monroe

Member
yes that alternative would have been 55 dollars cheaper. either way i have the cat ones now. I will do those test and update tomorrow
 
M

Mark250

Senior Member
I have a set of the cheap probes but the outer sheath is stiffer than the cat ones and the probes bend too easily for my liking
I prefer the cat ones
Mark
 
C

craig Monroe

Member
ok so i am very confused. I checked for 8 volts and had it (7.96v to be exact). when i went from pin 2-3 on duty cycle sometimes i would get a reading and sometimes not. when i did get a reading i would get 50% at doing nothing and then press up 20% and press down 79%. However when i would release the brake if i rolled up it would work sometimes and other times not. when i pressed down it never worked. at all these time the interlock warning lock was either lit or flashing. What does this mean and what should i do now? mind you it has a new RH joystick i installed and received from CAT.
 
You must log in or register to reply here.
Top