Cat 277c skid steer parking break issue, afraid I already know the answer.

[JThomas7]

I have a 2008 cat 277c skid steer. Serial JWF1478, 1400 hours. This thing was kind of handed down to me and I've used it off and on for the last 3 years. It's always had a blinking exclamation light on it for the 3 years I've used it. I read this is a level 2 code. Machine has always seemed to function normally and I've never had a way to check the code. In this time I've replaced a few hydraulic hoses, new tracks, battery, and an alternator. Done normal oil and filter changes. Other than that no real problems.

Now all of the sudden when you start it you usually can't get it out of park. The blinking warning light comes on the moment you turn the key on. Some times the light doesn't come on right away. When this happens you can take it out of park. The light always comes back on and when it does it's anyones guess when it's going to throw itself into park. Sometimes you can get it out, sometimes you have to cycle the key several times. Obvious there's something going on. Hydraulics all still work and operate when the parking break is locked in. We've bypassed the safety switches on the armrest and seat as a check. This does not fix the issue. it's my understanding also that if it was one of those safety switches the bucket wouldn't operate also. I've pulled the plug to the parking break solenoid and it's not getting voltage to it when the button is pressed. When voltage gets sent to the solenoid it shifts out of park. I'm imagining whatever code it's throwing is telling it not to shift out of park. No Cat dealers within an hour ether direction so I've tried to troubleshoot this myself. I have a buddy who is a former cat mechanic but he doesn't have a cat laptop to hookup to it and see what codes it's throwing. He did tell me the last hose I replaced is the hose to the parking break on the right side.

It did NOT do this until after I replaced the alternator. It set for about a month with the alternator out of it and when I put the new one in I instantly started having this problem. I thought just maybe it had something to do with this alternator but I stuck the old one in it just to see and it's still doing it so I'm thinking that's just a coincidence.

I'm sure I'm at a dead end without hooking a computer up to it but I have to at least ask.

 

[Mark250]

unless your machine hs the optional display on the right hand side its gunna be hard
why did you change the alternator if it was alright to refit as a test ?
mark

 

[JThomas7]

While the alternator wasn't putting out a charge before, the machine would at least function until the battery got low. It set for a while waiting on a new alternator. I feel like a rat or something had to chew a wire somewhere during that time.

 

[truecountry]

I have a 277c at work also ...If you look at top right corner of your cab your display is there.. you should have a up arrow -down arrow and another button I think is like a square with a i ...press up and squared i both at same time 5 times in 5 secs and ..then up for codes write them down and post it here....Codes will be listed e then numbers

 

[Mark250]

that is optional display only, not all machines have it
Mark

 

[JThomas7]

Yeah, if I had the display I probably wouldn't be here asking. Unfortunate deal, Cat guys coming out this Thursday to check it out.

 

[Mark250]

let us know it all works out
Mark

 

[JThomas7]

let us know it all works out
Mark

Well I was able to get a local cat guy out on his own time today. 37 times it's picked up a code for over voltage left joystick forward reverse. over voltage left joystick left right. He told me the list of things that could cause it. Checked all wiring for ohm readings and everything in the harness reads good. He's 98% sure (his words) that the sensor is out in the left joystick. Says as a safety precaution it's not letting it release the parking brake.

 

[JThomas7]

Well I was able to get a local cat guy out on his own time today. 37 times it's picked up a code for over voltage left joystick forward reverse. over voltage left joystick left right. He told me the list of things that could cause it. Checked all wiring for ohm readings and everything in the harness reads good. He's 98% sure (his words) that the sensor is out in the left joystick. Says as a safety precaution it's not letting it release the parking brake.

Any reccomendations on where to get the best price on a replacement? $526 from a somewhat local dealer.

 

[Mark250]

did he tell you the code s ,over voltage usually indicates open circuit
Mark

 

[Nige]

View attachment KENR8666-07 - 246C thru 279C SSL & 279C thru 299C CTL Electrical Schematic.pdf

Well I was able to get a local cat guy out on his own time today. 37 times it's picked up a code for over voltage left joystick forward reverse. over voltage left joystick left right. He told me the list of things that could cause it. Checked all wiring for ohm readings and everything in the harness reads good. He's 98% sure (his words) that the sensor is out in the left joystick. Says as a safety precaution it's not letting it release the parking brake.

Did you check the resitance in the harness while someone was pulling & tugging at it..? Often with open circuit issues if it's a "break" in a wire that sometimes is in contact and sometimes not then manipulating the harness while testing is the only way to confirm it. Often in such cases it's the vibration of the machine running that causes the open circuit and of course you are testing it with the engine off and everything appears hunky dory.

In case you haven't got one already here is an electrical schematic that suits your machine, so you will be able to see what wires to test for continuity and what each one does.
View attachment KENR8666-07 - 246C thru 279C SSL & 279C thru 299C CTL Electrical Schematic.pdf

For parts, try Offroad Equipment - www.offroadeq.com/

 

[JThomas7]

He explained it to me as it's sending voltage out but not getting anything back. Said that if it was a wire that most likely it would have been the forward reverse or left right. Probably not both. Even so he checked to make sure he was less than 5 ohms on several wires then hooked up to today the joystick and moved it around. He is going to return in a few days and try the new stick

 

[Nige]

As Mark said above, ask him exactly what Diagnostic Code it was showing. Based on experience there will be a detailed procedure for checking it that's a bit more complex than just ensuring a few wires have less than 5 ohms resistance IMHO ...... in the few days before he returns you could do the testing yourself, all it needs is to know what the Code is.

 

[JThomas7]

I'm afraid I made it sound like he spent less time than he did. He probably made 50 trips from the machine to the lap top. Both in the cab and underneath. Also pulled the 2 big square plugs under cab and was testing there. Also was making readings at the plugs under the arm rest as well.

On that note we just got to the hospital and the wife's in labor!

 

[Nige]

37 times it's picked up a code for over voltage left joystick forward reverse. over voltage left joystick left right.

Best of luck with your i9mpending arrival ........

When you have time confirm with him that the Diagnostic Codes are as follows: -

LH Joystick
Over voltage forward/reverse - MID039 CID2474 FMI03
Over voltage left-right - MID039 CID2476 FMI03

As I thought the troubleshooting procedures for both involve a bit more than ringing out the resistance of a few wires.

 

[Mark250]

I have come across this before. I agree with nige on the codes 2474 and 2476 are the most likely. before you replace the sensor group check a few things first. See if you have access to a digital multimeter with duty cycle and frequency measurements
first off check power supply to pin number 1 at the 6 pin connector at LH joystick base this should be 12Volt,also confirm you have good ground at pin number 2 at same connector. if no power at pin 1 check fuse as per drawing below


if these tests are ok proceed to check signal from joystick to ECM
without disconnecting anything set multimeter to frequency setting and check base frequency from sensor. connect meter between pin #2 and pin#3 move joystick and record frequency .repeat for pin #2 and pin# 5.should be about 500 hz
next switch meter to duty cycle or percentage and move joystick, readings should change in proportion to movement.
if these reading are ok your joystick is ok

 

[JThomas7]

I have come across this before. I agree with nige on the codes 2474 and 2476 are the most likely. before you replace the sensor group check a few things first. See if you have access to a digital multimeter with duty cycle and frequency measurements
first off check power supply to pin number 1 at the 6 pin connector at LH joystick base this should be 12Volt,also confirm you have good ground at pin number 2 at same connector. if no power at pin 1 check fuse as per drawing below
View attachment 156478View attachment 156479

if these tests are ok proceed to check signal from joystick to ECM
without disconnecting anything set multimeter to frequency setting and check base frequency from sensor. connect meter between pin #2 and pin#3 move joystick and record frequency .repeat for pin #2 and pin# 5.should be about 500 hz
next switch meter to duty cycle or percentage and move joystick, readings should change in proportion to movement.
if these reading are ok your joystick is ok

You guys are awesome, I appreciate all the support. I remember him talking about the duty cycle. The last thing test he did was the percentages also. He told me they were not changing when he moved the stick. Luckily for me he's willing to throw a joystick on the truck and let us test with a known good / new unit.

 

[Nige]

On the assumption that 2474 03 & 2476 03 are the Active Diagnostic Codes that you actually have on your machine below you'll find the Troubleshooting procedures for both.

View attachment MID039 CID2474 FMI03.pdf
View attachment MID039 CID2476 FMI03.pdf

Personally I have my doubts that both the forward-reverse & left-right position sensors can have failed at exactly the same time. It's stretching the bounds of possibility as far as I'm concerned, although I admit it is possible. Therefore I'd be looking closely at the power supply and the ground wires to the left joystick that are common for both position sensors.

 

[JThomas7]

He stopped by between jobs today and plugged a new joystick in to test. It cleared all codes and read percentages when he moved it different directions..

I also printed out the troubleshooting procedures, he said those are the procedures he went over last week.

My top glass has been off about a month, wondering if it maybe got wet in there and cased it. but he said they make similar machines in open station so he doubted it. Said there was a service bulletin for this model about bad left joysticks but my serial # wasn't covered under it.

 

[Nige]

You said earlier that you got the tech to stop by your machine on his own time. I don't have a problem with that but is he offering to sell you the replacement joystick or did he simply bring one along just to perform a test and now he's identified that the joystick appears to be the problem you have to go out and buy one yourself..? You can see the way my mind is working here .......

I'll repeat that to me it's very unusual for both position sensors on a joystick to go out at exactly the same time - not impossible, but highly improbable. The much more likely root cause would be for a problem in the common power supply or in the common ground. Do you have any way that you could do the Troubleshooting procedures in Post #18 yourself..?

What is your S/N anyway..? Maybe Mark can run something down regarding a Service Letter to double check.