980 K Cat loader scales problem

[kshansen]

We have a 980K with about 1,400 hours on it. About a week ago the operator started complaining about the scales becoming erratic. Some times trucks would be up to 6 tons over what his scales indicated and then up to 6 tons under. After having no luck working on them our selves we called in the dealer and both their mechanic and dealer specialist have tried to calibrate them with no luck.

Going through the steps of the calibration either using the machine's computer or Cat ET it gets to the point you raise a loaded bucket at normal operating speed and then lower bucket to ground. No matter how many times you do this it keeps asking you do do it. Never moves on to the next step in the program like it should.

Dealer is waiting on Cat to offer some explaination or way to correct this problem. Just wondered if anyone else is having a problem of this nature.

 

[koecon]

I have not seen this on other 980K's but
have a fair amount of experience with
the CAT payload systems. It sounds to
me like one of the signals that the system
is monitoring like lift cyl. pressure or lift
arm position is out of range keeping it
from calibrating.

 

[Per Eriksson]

Do calibration of both tilt and lift sensors first if not done?

 

[koecon]

Yes I would do that and monitor lift cyl.
pressure to see that it's not erratic.

 

[kshansen]

Dealer rep. has told me that Cat told him the computer will not allow calibration unless it senses calibration is needed! Now that does not sound right to me. This machine is one they do not want to take out of service unless I or Cat knows that it can be fixed so I will have to put off doing anything for now. It should be coming due for a 500hr. service soon so at that time I may try starting with the tilt and lift sensors calibration. Maybe if I do that the computer will think the pressure sensors need calibrating and let me get past this log jam in the program. I suppose I could disconnect the pressure sensors then run machine causing a fault then reconnect them and do the calibration as if they were new sensors!

 

[koecon]

You should be able to calibrate any time
you replace a sensor so I would try the
disconnect.

 

[Nige]

Dealer rep. has told me that Cat told him the computer will not allow calibration unless it senses calibration is needed!

Bull.....!! You can recalibrate sensors at any time. As others have posted I would calibrate the angle sensors for Lift & Tilt functions first. If that is not done and a value is stored in the ECM that is outside the current range of movement then that's the reason the step of asking the operator to raise a loaded bucket from the ground up to max lift is failing every time, the actual sensor angle at full lift does not correspond to the stored value.

Has anyone been into the lift angle sensor recently..? Pin change, operational damage, something like that..?

If the Cat man hooks up ET to the machine, go to the Implement ECM, select calibrations, and tick the boxes to calibrate the Lift & Tilt ange sensors. From there follow the instructions. A tip - when it tells you to extend the lift cylinders completely and then press "OK", lower the bucket about 1/2"-1" before pressing OK. That should correspond to the true angle of the Lift Arm sensor at the time the Lift kickout activates, rather than looking for the angle at full cylinder extension.

 

[kshansen]

Bull.....!! You can recalibrate sensors at any time. As others have posted I would calibrate the angle sensors for Lift & Tilt functions first. If that is not done and a value is stored in the ECM that is outside the current range of movement then that's the reason the step of asking the operator to raise a loaded bucket from the ground up to max lift is failing every time, the actual sensor angle at full lift does not correspond to the stored value.

Has anyone been into the lift angle sensor recently..? Pin change, operational damage, something like that..?

If the Cat man hooks up ET to the machine, go to the Implement ECM, select calibrations, and tick the boxes to calibrate the Lift & Tilt ange sensors. From there follow the instructions. A tip - when it tells you to extend the lift cylinders completely and then press "OK", lower the bucket about 1/2"-1" before pressing OK. That should correspond to the true angle of the Lift Arm sensor at the time the Lift kickout activates, rather than looking for the angle at full cylinder extension.

No pin changes or anything of that nature machine has only 1,624 hours on it as of 2:00pm today.

As I said machine is one that they won't park until service work is required and it's working hours are more than I'm allowed to work, no overtime without permission from God or someone higher up than him! It is coming up for service in a couple weeks so I hope to slip in some time to play with the calibration of sensors. I like the idea of kind of lying to the computer about the full extension of the lift cylinders, will do that.

I'll make sure to report what I find at that time, Thanks for the advice.

Ken