Cat 277B Aux hydraulic does not work

[Iggys6]

Hi am new to the forum. I have a 2005 Caterpillar 277B that I recently bought that came with a bucket. Just over the weekend I bought a brand new grapple and went to hook it up and I have no auxiliary hydraulics. I've been reading everywhere to look into the thumb wheel switch and test that but I found the 4 pins for it just don't know which one to test and where. Also is there anything else I should look for? Solenoids? Relays? All the fuses are good. I would really appreciate the help, I am stuck without the grapple. Thank you in advance.

 

[Mark250]

Hi. first off serial number please. do you have any fault lights on?. do you have the optional right hand display console?
Just be aware The auxiliary ECM has been known to fail on these machines however there are a few simple tests you can do to try and isolate the problem.
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
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.
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.
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 .
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
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

 

[Iggys6]

Mark250, Thank you for the reply! The serial number is CAT0277BEMDH02115. I do not believe I have any fault lights on. When the machine is running I have no lights on the dash. I do not believe I have the optional display console. Where are the aux solenoids? Are they on the hydraulic block under the cab? Between pin 1 and 2 on the right joystick that is for the thumb wheel correct? Do I move it up and down to test it?

Hi. first off serial number please. do you have any fault lights on?. do you have the optional right hand display console?
Just be aware The auxiliary ECM has been known to fail on these machines however there are a few simple tests you can do to try and isolate the problem.
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
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.
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.
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 .
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
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
View attachment 160282

 

[Iggys6]

Also I don't have a led test light. I can go buy one If needed. I only have a bulb one but I do have a power probe if that would work. Thanks

Hi. first off serial number
please. do you have any fault lights on?. do you have the optional right hand display console?
Just be aware The auxiliary ECM has been known to fail on these machines however there are a few simple tests you can do to try and isolate the problem.
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
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.
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.
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 .
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
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
View attachment 160282

 

[Iggys6]

Hi just tried to test the solenoid. Which solenoid do I test A1 or A2? Do I keep the connectors connected and then splice the wire or is there another way? Also doesn't the button on the far left do something? I know I press the button under the horn and then it should enable the aux hydraulics?

 

[Mark250]

Where are the aux solenoids? Are they on the hydraulic block under the cab? Between pin 1 and 2 on the right joystick that is for the thumb wheel correct? Do I move it up and down to test it?

yes under the cab
you don't need to move thumb wheel to check 8 volt supply at pins 1&2

 

[Mark250]

Also I don't have a led test light. I can go buy one If needed. I only have a bulb one but I do have a power probe if that would work. Thanks

the output from the ECM is digital. a non LED test light can cause an additional fault due to excessive current draw giving misleading results
as for the power probe I honestly don't know much about them and for that reason I would not use it

 

[Mark250]

Hi just tried to test the solenoid. Which solenoid do I test A1 or A2? Do I keep the connectors connected and then splice the wire or is there another way? Also doesn't the button on the far left do something? I know I press the button under the horn and then it should enable the aux hydraulics? View attachment 160303

check both solenoids one at a time. you leave them connected and back probe with paper clips or you can purchase special probes that fit in the back of the connector moving the thumb wheel one way will active one coil moving the other way will active the other coil

 

[Mark250]

Also doesn't the button on the far left do something? I know I press the button under the horn and then it should enable the aux hydraulics?

the button on the far left is for pressure release in the aux hydraulic lines

not sure what you mean by button under horn, are you meaning the left hand joystick horn button and the cont flow button
the auxiliary/high flow switch is as circled


here is brief circuit of aux switch and connections to ECM to operate one of the contacts must be grounded for either standard flow or high flow


Mark

 

[Iggys6]

Thanks mark for all the help so far. However, I do not have button #10 does that matter? Also to check pin 1 and 2 on the thumb wheel I leave every connected right and back probe that also? Thanks!

 

[Mark250]

yes .Button #10 will only be there if you have the high flow option, just means you have standard flow only. sorry about my first reply lot of typos in there.
Mark

 

[Iggys6]

No problem I really do appreciate the help. Great forum so far! I need it working by this weekend so that's why I am in such a rush. So how exactly do I test the solenoid? I backprobe the led test light to both pos and neg on one at a time. Then I lower the cab and turn it on, turn off parking brake, hold the button below the horn, bottom left for 3 seconds then release. And then I should see it light up if it's functioning? Or do I have to move the thumb wheel too? Sorry for all the questions. I'm decent with electrical but this is the first skidsteer I've owned.

 

[Mark250]

No problem I really do appreciate the help. Great forum so far! I need it working by this weekend so that's why I am in such a rush. So how exactly do I test the solenoid? I backprobe the led test light to both pos and neg on one at a time. Then I lower the cab and turn it on, turn off parking brake, hold the button below the horn, bottom left for 3 seconds then release. And then I should see it light up if it's functioning? Or do I have to move the thumb wheel too? Sorry for all the questions. I'm decent with electrical but this is the first skidsteer I've owned.

if you have the joystick similar to the one below. the button below the horn is for cont. operation and there is no need to use it for normal operation of the thumb wheel. you just need to move the thumb wheel and the leds and or function should work


Mark

 

[Iggys6]

Ok thank you! Yes that is the joystick i have. I just bought a "computer safe" led test light I will test it in a couple hours when I am near the machine.

 

[Iggys6]

Ok I accidently bought a logic probe. It's a led test light with a probe and then pos and neg alligator clips at the end of it. Not sure if that would work so I put paper clips in one solenoid like this and checked for power with my meter while moving the thumb wheel and I have no power. Am I doing something wrong or should I move onto the thumb wheel? Thank you

 

[Iggys6]

Also what's your thought on a product like this? I know it's not genuine but if it works it works.

Thanks mark.

 

[Iggys6]

Also just checked pin 1 and 2 for power with my meter. I turned the key, engine off and got 8 volts.

 

[Iggys6]

Just checked pin 2 and 3 on duty cycle for anything and with the key on and with engine running I get 3.6v and that's it. I move the thumb wheel both ways and I do not a change if that's what I have to do.

 

[Mark250]

Also what's your thought on a product like this? I know it's not genuine but if it works it works. View attachment 160330

Thanks mark.

sounds like a good deal, but check that it has the ET program it may just be the comms adapter kit

 

[Mark250]

Also just checked pin 1 and 2 for power with my meter. I turned the key, engine off and got 8 volts.

good so far, means that you have power to ECM and that it is powering the joystick
mark