Cat 277C yellow exclamation warning and beeper.

[Nige]

I'm also feeling a pull to the left...if the left drive motor was not turning at the same speed as the right, it could throw the code for the sensor correct? im replacing fluid in drive now.

I don't think so, because when you want to turn surely one motor has to move at a different speed to the other, right..? So as I see it the signal from the LH & RH speed sensors is going to be different at anything other than moving in a straight line.

You will note that there are 2 separate speed sensors on each side (#1 & #2), despite the fact that there is physically only one sensor body. The power supply and ground wires are common, the signal wires are separate (see post #13 on page 1). So if the LH sensor #2 is not throwing a diagnostic code, and you say you have replaced the LH sensor assembly with a new one (thus ruling out the possibility of a dodgy sensor), then the only possibility as I see it is that something is wrong with the signal side of the LH #1 sensor. That's different to the situation where both sensors on one side are giving Diagnostic Codes at the same time then the problem could possibly be in either the power or ground wires - or both signal wires. But one sensor only seems to indicate something in the signal wire.

I'm not 100% sure that a pure continuity check will show up a problem. Have you actually physically checked the signal wire for damage right the way from the sensor to the ECM..? Also I'd suggest to have a very close look at the male & female pins inside each Deutsch harness connector to eliminate the possibility of a bad connection inside a connector on that signal wire caused by a loose or misaligned pin. The pins push into the connector and are retained by a pair of plastic "ears". If the ears don't grab hold of the pin properly then when the 2 halves of the connector are joined up it can physically push a pin out by a hair and leave you with a bad contact.

 

[DSHEQUIP]

Ok, thank you. Ill check that tonight..

 

[Nige]

If you want a copy of the Electrical Schematic then send me a PM with your email address.

 

[DSHEQUIP]

So i checked every wire from the ecm to the sensor. Everything checked good, only one last thing to do....i swapped the sensors from LH to RH. Tested it in the yard and was all good for about 10 minutes. And its back. This time with the 2687-8 code. All points to faulty sensor. Which is a big surprise considering its brand new.

 

[Nige]

If the same Diagnostic Code moved from one side of the machine to the other when the sensors were swapped then the only possible conclusion IMHO is a bad sensor. So long as you still have the delivery paperwork take it back and exchange it for a good one.

 

[DSHEQUIP]

Swapped with new sensor and runs like a champ. Thanks for your help Nige!

 

[Nige]

Nice to hear it's fixed. TBH it fooled me when you said earlier you'd put a new sensor on it, one would assume that a new sensor would work correctly. That assumption kind of sidetracked the diagnosis process.

 

[Dabo1]

speed sensor 277c

Nigl,
I need a wiring diagram for the 2008 277c, I have speed sensors problems. I replaced both sensors and still have the problem. Please help.

Thanks
Dabo1

 

[Nige]

Post a Serial Number so that I can find the correct schematic and you're welcome to it.

 

[Dabo1]

Serial #

Jwf01905

 

[James Sanderson]

Hello I am glad I stumbled on this forum I am having the same issue with my 2016 239D it started about a month ago it has 300hrs on it and I bought it new the salesman I bought it from told me to check the grounds first before I brought it in which was ok with me as it would probably sit there for 2 weeks before they did anything to it but anyway today I lifted the cab and washed it all out and cleaned it up and was checking the grounds for any loose connections and I didn't find any so I found you guys here and started reading so I went to my shop and the first thing I did was check the connections to the speed sensors I took them apart sprayed them with contact cleaner the took the air hose and blew them out and knock on wood It may have fixed it I didnt get to run it much this evening to really check it out but I will tomorrow and if it does it again I will come back and see if anyone has any suggestions but so far so good thanks for the input to others as it was very useful to me James

 

[AK Red]

Post a Serial Number so that I can find the correct schematic and you're welcome to it.

HELLO
I

Thanks to Nige for the electrical schematic.

Today I spent hours trying to trace the issue. Cabin up, external covers behind the tracks off and then traced the wires from ECM to sensor on both sides. The right side cable was beautifully placed in a cleft created by the two hydraulic lines. Well protected and laid. Left side was a mess. Wrapped around hydraulics, more exposed, clearly no care placing that when the machine was wired. Off with the cable ties and lay the look properly and inspect every cm at the same time. Pop off both plugs and they were perfectly clean, not even a spec of dust had penetrated the plug seals.

The sheath close to the sensor was wrapped around the hydraulic fitting and then went down to the sensor but there were two small perforations in the sheath close to the large hydraulic nut. I pulled the sheathing back and couldn't see any damage to any of the four wires though.

Once I was happy with everything, I closed up the machine and tested it. I also found that the tracks were about 24mm and 28mm slack and should be 12 - 14mm with a 45kg load so I adjusted these at the same time and did a full grease job.

I barely moved the machine before I got the dreaded ! warning and the damn beeping. Instantly the machine slewed to the right and was difficult to straighten. 200m of driveway improved the handling a little but it still pulls left and even after multiple restarts the ! warning and beep don't go away.

My CAT ET interface unit comes up with the same error but this time the error is active and can't be cleared. So it appears that I may have had a dodgy wire or sensor and moving things has made it worse and now it's plating up constantly.

Bugger!!

So looking at that sensor via a telescopic mirror, I tried and tried to get a tool on the head of the retaining cap screw but to no avail. Unless there is some crazy tool it appears that either the main hydraulic feed needs to be removed or the motor slid out to allow clearance to get an allen key in there. A two minute job on a wheeled machine looks to be a nightmare on a tracked machine.

Without an SIS I'm a bit stumped as to how to replace that sensor. Impossible to think that Caterpillar would not design that sensor to be inaccessible when it's clearly a serviceable item?

Has anybody here actually done one that can give me a pointer or three?

I'll order a new one tomorrow. I'll check with Cat in Melbourne but I'm thinking that it's going to be prohibitively expensive and I may have to get one from the States. Seems that the part number is 2623764 and it looks like the attached image. Would anyone with a parts manual care to confirm the number for me please?

 

[AK Red]

HELLO
I HAVE A 2008 CAT 277C WORKED GREAT UP TILL COUPLE DAYS AGO. WITH 8' SNOW BUCKET IN MID LIFT THE YELLOW EXCLAMATION POINT OF DEATH CAME ON AND HYDRAULICS TO LIFT AND BUCKET, IT QUIT ! !
THE TRAVEL STILL WORKS.
1) IS THERE A GOOD SET OF WIRING DIAGRAMS.
2) IS THERE A BEST PRACTICE AS TO EFFICIENTLY RIP & TEAR TO FIND WIRING ISSUES
3) I HAVE THE ERROR CODES. IS THERE A LIST OF ALL COMMON CODES AND EXPLANATIONS
4) CAN I CLEAR OLD CODES, TO TELL WHICH MAY STILL BE ACTIVE ISSUE

MACHINE HAS BOUT 9500 HRS
ID#CAT 277C JJW501587

 

[Nige]

Your Serial Number appears to be incorrect - JJW is a D10T.
Are the last 8 characters of the PIN JWFxxxxx.?
Correct Electrical Schematic will be determined by the Serial Number.

What Diagnostic Codes do you have and which of them are Active..? Post a list.

Just FYI, there's no need to shout. Using caps is considered shouting on a forum such as HEF.

 

[AK Red]

*CAT0277C JJWF01587* OOOPPS ! !
THE #5 KEY AND UP ARROW
2475-3
2477-3
ACTIVE ?????
OLD ?????
HOW TO TELL IF OLD OR CURRENT?
CAN RESISTER BE CLEARED TO ONLY SHOW CURRENT
ITS A 2008 9500 HOURS DOUBT ITS EVER BEEN CLEARED BEFORE

 

[Nige]

Your Codes both relate to the position sensors for the RH joystick. One is for the front/rear sensor, the other for the left/right sensor

Attached are the Troubleshooting procedures for both Codes. I'll send you the Electrical Schematic separately.

 

[AK Red]

Your Codes both relate to the position sensors for the RH joystick. One is for the front/rear sensor, the other for the left/right sensor

Attached are the Troubleshooting procedures for both Codes. I'll send you the Electrical Schematic separately.

THIS WILL BE VERY HELPFUL
THANK YOU VERY MUCH

 

[John Galt]

Hi, I have a 257D that is throwing the right #1 and #2 warning E570-2 and E570-1. There's also a red warning that comes up about unexpected speed protection not engaged, speed will be limited, but it isn't limited at all.

So, I traced the wire to the drive and checked the voltage from yellow to white at the 2 points where it appears you can disconnect them (under the cab where it splits from the loom and just outside under the shroud where it connects to then finally go to the drive.

At both places I have 8V on yellow and white. On the other 2 colors to yellow I have 5V and 3V respectively, which would indicate that there is something on there. (PWM I would assume) which indicates to me that it isn't the wiring, but the actual speed sensor unless it could be way up on the back wall where there is an issue, but then I wouldn't be getting 8V and the other two wouldn't be getting anything I would think. I've cleaned all of the contacts anyhow to no avail.

One stupid question before I spend lots of money, could it be that the error codes are firing because the wires are backwards to each drive? (the color code is Purple on one and brown on the other, but to the drives they're both purple...) If it could just be switching them, then cool.

So I'm left to assume that it's the sensors on the drive that are screwed. But damned if I can figure out how you take it off without dropping the entire track and drive unit off the axels (not my idea of fun without another piece of equipment to lift them back on, which I don't have).

Does anyone have the procedure for how to get the sensor off the drive? Any pictures? I can barely see with the track slid as far as it will go off the axel before it falls off, so I can't tell what I'm working on.

Thanks in advance!

 

[Nige]

Try a Serial Number first (8 models to choose from), then answer a question - do you have an electrical schematic.?
If your DMM has the capability of measuring duty cycle you can measure the PWM signal from the speed sensors.

A comment. It may well be that at some electrical connectors (especially at sensors) the wire colour/number on one side of the connector is different from what's on the other side.

 

[Curtis Baker]

Uzz, Do you have the Electrical Schematic for your 277C..? If not do you want one..?
If yes send me a PM with your email address and your machine Serial Number.

I have a 277c and would like the wiring schematic for the speed sensors too please serial #JWF01719