Cat 277B Aux hydraulic does not work

[Mark250]

Hi Craig, The 20% to 80% is what you should be getting ,however I don't understand why the duty cycle does not change when you release the park brake, unless there is some issue with the wiring .Have you checked the harness from the joystick to the ECM?
The output from the joystick is only a proportional signal to the ECM which then controls the functions.
As stated earlier the Aux ECM has been known to be problematic
Cat ET is probably your best bet at this time
here is a fault light chart that may help

 

[craig Monroe]

I have a IDEAL 61-340 multimeter. I am wondering if it does not have the ability to read DC Duty Cycle. Reading through the manuel it appears that it can only read AC duty cycle. This may be why i am having such a issue getting a read. or should i say a consistent read

 

[craig Monroe]

I just threw a different multimeter on it and turned the engine on with the parking brake on and rolling it forward i got about 20% always then not rolling it i got 50% and rolling it downward it went to zero every-time. Does this make any more sense?

 

[Mark250]

No, 20% rolled forward is good,50% not moving thumb wheel is good but rolled backwoods should be about 80%sozero is definitely not good
I am wondering out loud if you have a faulty joystick
did you repair or replace the joystick or roller
As for the multimeter. Years ago I bought a snap on multimeter, cant remember the model but it would only measure duty cycle at below 200 hz
Can you supply an 8volt supply to the roller and check off the machine to confirm operation
Small power supply are quite cheap and it is how I confirm sensor operation be it digital or analogue
Mark

 

[craig Monroe]

Yes I can do that as well as I am going to get my hands on another multimeter that is pretty new and see if results change. The joystick was new from cat bet I could bring it there as well and they would test it. Before that let me get a newer meter on it.

 

[Nige]

it may be a bit off the wall and we all know lightning doesn't strike twice in the same place, but check out this guy whose 299D wouldn't move. He put a new joystick on it and the problem was the same. Traced to a pin in a connector not making proper contact. Your attention is drawn to post #118 on Page 6. Just worth checking.

https://www.heavyequipmentforums.com/threads/cat-299d-wont-move.77979/page-6

 

[craig Monroe]

It is worth trying, what makes things more difficult is that just before this issue started to happen cat had it replacing the hydraulic motors. I bet they had all sorts of connectors apart. Is the "J1" connector they are talking about the one one for the right joystick?

 

[Mark250]

Hi Craig, J1 is one of the connectors on the ECM
I am still not understanding why you are not able to measure the duty cycle of that joystick roller
if you have a 8volt supply that is stable while operating the roller switch you should be able to measure the varying out put at the connector with the spoons placed into the back of the connector
if you cant get that signal, it is a waste of time going any further, which is why I asked you to check off machine to verify that the replacement joystick is OK
you can physically leave the joystick in the machine just remove the signal wire from the connector and test as before
Just a thought. grab some spare connector pins and check for fit in the connector to make sure that any testing work has not enlarged the connectors and is making poor contact. You should feel a slight drag as the pins are paced into the connector
Mark

 

[Nige]

Craig, if you don't have an Electrical Schematic for your machine feel free to PM me with the Serial Number and your email address. I can send one to you. If nothing else it will give you a handle on the expressions like "connector J1" and such, and show you where they are located.

 

[craig Monroe]

It ended up being the aux. ecm. One part of it went and the old one on the bottom that was hidden had a hole in it.