cat 953 steering issue

[mobile-tech]

have a 953 2zn03684 -machine has right at 7k on it - came in from job said it didnt turn, ran it in the yard for 15-25 min seemed fine the heat wasnt working and i thought they might just wanted a different machine

back at another job worked fine til machine got good and hot after a few hours of running steers hard or doesnt want to steer unless you stomp on pedals then it will turn - machine hauled back to yard and steered fine into shop codes i have 079-0466.03 - i dont have ET and all i know id that a trans code
any help is appreciated

 

[Nige]

079-0466.03

Left steering pedal position sensor - hellooooooooo..........

I need to find the specific proceudre for it. Back shortly.
If you end up replacing a sensor as a result of the diagnostic the new one will require calibrating (see attached) or you will get an 079.0466.13 Diagnostic Code. You have the advantage that the Click Box switches are built into the RH armrest.

 

[mobile-tech]

hello, thank you- back to the yard soon and I’ll go from here

 

[Nige]

Here's the troubleshooting procedure for 079.0466.03.
If you need a complete electrical schematic just ask.

 

[mobile-tech]

the code doesnt have serv code lit up next to it so it must not be a current fault -per the troubleshooting

 

[Nige]

the code doesnt have serv code lit up next to it so it must not be a current fault -per the troubleshooting

There was me assuming it was an Active Code. the troubleshooting procedure will not work unless the particular Code is Active.

Use the Click Box switches under the armrest, get the Monitor Panel into Service Mode, and try erasing it.

 

[mobile-tech]

Access into service mode and was able to clear code , exit out and cycle key check for codes none present

 

[Nige]

Access into service mode and was able to clear code , exit out and cycle key check for codes none present

In that case you are into Hystat system testing.

From memory the first thing you need to confirm is the engine High Idle (2325±50 RPM) speed before moving forward.

Attached some info on the Hystat T&A that might be useful. Based on your comment above "back at another job worked fine til machine got good and hot after a few hours of running steers hard or doesnt want to steer" my suspicion would be one or more internal leaks in the hystat that increase as the oil gets more fluid - YMMV.

 

[mobile-tech]

thanks i will proceed with this

 

[Nige]

This might help you see a way forward.....

In the OP you state that the fault occurred when the machine was hot. Clearing the logged codes, it seems logical to get the machine hot again and try to replicate the fault.

The comment about having to stomp on the pedals to get it to turn is strange because the pedals only move a rotary PWM sensor so it shouldn’t matter how hard you stomp on them, unless the signal from one of them is getting intermittent when the floor (i.e. the position sensor) warms up.

If it does start playing up again once it is hot and logs a steering pedal sensor code, I would carry out the engine-off and engine-on calibrations as a first step.

EDIT: Just to be clear in the above I was referring to ALL the calibrations in the order they are listed in the T&A attachment above. Starting with the engine off ones in order and followed by the engine-on calibrations, again in the particular order they are set out in the T&A document.

 

[mobile-tech]

Yes I’ll have to try that - as per the usually I’m bouncing back and forth between repair projects

 

[Nige]

Yes I’ll have to try that - as per the usually I’m bouncing back and forth between repair projects

Please do that as a 1st step before you break out the pressure gauges.

 

[mobile-tech]

hopefully have time to run that machine tomorrow been bouncing around from a engine job,field repairs and pm’s. If it sets a code after I get it good and warmed up continue with the calibration from the t&a file provided.