Cat 277C Parking Brake Won't Disengage

[Weekend_Warrior]

You unplugged the solenoid and did nothing else, them checked the codes? Next is to short the wires together and re-check the codes. If nothing changed with either condition the sensor shouldn't be your problem.

You checked resistance from wire end to wire end (yellow sensor end to yellow ECM end)? Did you check wire to wire (white to yellow) to make sure they're not shorted together?

Did you preform a tug test on the ends mounted in the connectors to make sure they're not loose?

Thank you for the feedback.

I unplugged the solenoid, jumped the two contacts, and then checked codes. Code did not change.

I did not check wire end to wire end, but that's a good suggestion and I will give that a try. I did check white to yellow and there was continuity.

I did tug on the wires between the checks and there wasn't any change. However, I was alone so next time I will try tugging while somebody else is actively measuring the resistance.

 

[Weekend_Warrior]

Key question. When you pulled the Codes using the Monitor were the 5 you listed above Active (Service Mode 1) or Logged (Service Mode 2).? If they were Logged the troubleshooting procedure is not likely to find anything, you need the Code to be Active in order to troubleshoot it correctly.

TBH with the problem coming & going as it appears to be my money would be on a wiring harness connector somewhere that has condensation, corrosion, etc, in it, or even a wire rubbed through somewhere.

It might pay you to identify all the major harness connectors between the ECM and the park brake solenoid, open each one up in turn, treat it with electrical contact cleaner then move on to the next one. If there are none then at least clean the ECM connector (J2, Pin 2) and the 2-pin connector at the solenoid end.

I was in service Active Service Mode 1.

Knowing that the drain ports on the bottom of the machine have been plugged ever since I owned it, I am starting to agree with you that there may be a condensation, corrosion problem. But isn't it strange that this problem occurred immediately after I replaced a hydraulic line? The entire hydraulic system was drained and refilled so is it just a coincidence or did I wreck something upon startup with air in the lines?

 

[Weekend_Warrior]

Here is an interesting post I found with somebody dealing with the same issue on a Cat 262C:

https://www.justanswer.com/construc...262-one-side-will-not-release-park-brake.html

The technician brought up the possibility of the metal nut on the solenoid being an issue and should be replaced with a plastic one.

catmastertech :
You should have a plastic nut on this solenoid.

catmastertech :
The parking brake solenoid on certain skid steer loaders and multi terrain loaders may not function properly which will result in the parking brake not working with the key switch in the "ON" position. The issue is caused by the steel nut on the back-end of the solenoid becoming magnetized through use affecting the plunger’s ability to shuttle properly.

Have you guys seen this happen before?

 

[Nige]

But isn't it strange that this problem occurred immediately after I replaced a hydraulic line? The entire hydraulic system was drained and refilled so is it just a coincidence or did I wreck something upon startup with air in the lines?

Not likely IMO. Coincidence I would suggest. In actual fact there are no connectors at all between the one at the solenoid and the 70-pin connector J2 of the ECM.

Knowing that the drain ports on the bottom of the machine have been plugged ever since I owned it, I am starting to agree with you that there may be a condensation, corrosion problem.

I'd suggest thaf if you haven't checked for that yet then you should do so. Start with the ECM I would say.

 

[Weekend_Warrior]

I thought I discovered the issue but got kicked down again. I pulled the parking brake valve and discovered that the snap ring and screen on the end was missing. Figured that was my issue since the valve was clearly not operating anymore. Whatever components inside the valve are no longer in there and probably somewhere in the gear pump or lines.







I ordered a new valve and solenoid from CAT and installed it this morning. To my dismay the machine is still locked out from the Parking brake.

I switched joystick bases for the chance that was causing it since that was the issue in a few other posts, but no luck.

I’m going back to check the wiring again for the parking brake circuit but I’m really surprised the issue wasn’t related to the valve based on what I saw on the old one.

 

[Nige]

Figured that was my issue since the valve was clearly not operating anymore. Whatever components inside the valve are no longer in there and probably somewhere in the gear pump or lines.

To the best of my knowledge the function of the screen on the valve is only to keep particles the size of tree branches, small children, & dogs out of the critical internal parts of the valve assembly. AFAIK the solenoid valve will function just fine without them.

Did you try applying 12v directly to the coil of the old solenoid valve.?

 

[Weekend_Warrior]

I like your sense of humor, Nige.

I didn't test the old solenoid as I didn't see the point since the new valve came with a new solenoid. What's strange is that after sitting for a few days the parking brake will disengage momentarily and then lock up again and stay locked up. Over the past 2 weeks of trying to get it to move I was able to get it back on a trailer and back home. Troubleshooting has slowed down since it's at home and not sitting on a job site, but I will be revisiting the wiring and connections this coming weekend.

Looking Back - when I replaced that leaking hydraulic line, I spent about 4 hours spraying every dirty spot under the cab. Coincidentally, I am getting this parking brake issue immediately after.

Can you help me locate the left and right drive motor speed sensors? Since I am getting the codes for them, I am curious if I got the connections to them wet and that could be contributing to my issue?

2685-8
2686-8
2687-8
2688-8

At one point, the 681-5 code did go away and I was left with just the left and right drive motor speed sensor codes. But the 681-5 came back quickly.

 

[Nige]

I didn't test the old solenoid as I didn't see the point since the new valve came with a new solenoid.

I think you should test the old valve with its solenoid installed to see if you can get the guts of it to move by applying battery power.

Can you help me locate the left and right drive motor speed sensors?

Back side of the drive motors. Area B on the illustration, #7 on the detailed view. Held in a by a single socket head (Allen) bolt.

 

[Weekend_Warrior]

I think you should test the old valve with its solenoid installed to see if you can get the guts of it to move by applying battery power.

Back side of the drive motors. Area B on the illustration, #7 on the detailed view. Held in a by a single socket head (Allen) bolt.

View attachment 303647View attachment 303649

Thanks, Nige. I don't think it's the speed sensors since I did not disturb that area. And for both sides to be out simultaneously that would be too much of a coincidence.

I think I smell what you are stepping on now. You're wanting me to function test the old valve to verify if it was even getting a 12V signal. I will try that tomorrow and let you know what I observe.

 

[Nige]

Thanks, Nige. I don't think it's the speed sensors since I did not disturb that area. And for both sides to be out simultaneously that would be too much of a coincidence.

You could have got "water in the works" somewhere in the wiring where the wires from the speed sensors from both sides of the machine come together.

 

[Weekend_Warrior]

You could have got "water in the works" somewhere in the wiring where the wires from the speed sensors from both sides of the machine come together.

That's actually very possible and a good thought to check. I was on a mission and sprayed a heck of a lot of water all around.

 

[Nige]

That's actually very possible and a good thought to check. I was on a mission and sprayed a heck of a lot of water all around.

Generally the type of connectors used by Cat (Deutsch brand) are pretty resistant to water ingress from spray, but if large quantities of water are sprayed directly on a connector it is quite possible for some of it to find its way inside.

Look on Page 2 of the electrical schematic, Grids D-12 & G-12, and you will find the LH & RH motor speed sensors. The harnesses for them are also shown on the hydrostatic lines group (attached). They are shown as being zip-tied to the hydraulic hoses.

 

[Nige]

Thinking a bit more, I suspect a glitch on the signal side of the speed sensors rather than the power supply and ground, although they shouldn't be overlooked.

Those sensors are supplied with stabilized 8v power, and grounded back to, the Machine ECM. However they are only two among about eight or so sensors that are similarly powered. A loss of power or ground throughout the machine in that power supply circuit ought to generate some sort of CID 0041 Code relating to the 8v.

 

[Weekend_Warrior]

Thinking a bit more, I suspect a glitch on the signal side of the speed sensors rather than the power supply and ground, although they shouldn't be overlooked.

Those sensors are supplied with stabilized 8v power, and grounded back to, the Machine ECM. However they are only two among about eight or so sensors that are similarly powered. A loss of power or ground throughout the machine in that power supply circuit ought to generate some sort of CID 0041 Code relating to the 8v.

Thanks for the additional details, Nige.

Fought a lot of fires this week so I wasn't able to test the old parking brake solenoid. I also left it at the work office after a show and tell with the Lads, so I won't get to test it this weekend either.

Today I checked the speed sensor wires and discovered why I was getting codes for speed sensors of both sides. One of the sensor plugs under the cab had a wire exposed from rubbing. The other sensor plug had oil residue inside, likely from sitting on the cab floor. Therefore, I recant my previous statement that "speed sensors for both sides to be out simultaneously would be too much of a coincidence". Apparently, anything can happen.





The parking brake did disengage momentarily after initial startup following correcting the speed sensor plug issues. I even got out of the seat to see if the issue would come back - the parking brake engaged after I got out of the seat and then disengaged a second time when I sat back down and pressed the switch. I was just about to celebrate but then the yellow driver alert indicator started flashing and the parking brake light showed back up. This all happened within 1 minute.

Somewhat good news is the 4 codes related to the speed sensors (2685-8, 2686-8, 2687-8, and 2688-8) are no longer showing on the active diagnostics mode 1. After seeing the exposed wire for the speed sensor plug, I truly thought I found the issue since it makes sense the parking brake would engage if the machine cannot sense the wheel speed.

I also cleaned all of the grounds that I could identify. And loosened and checked all of the plug connectors - all of which looked clean inside. No luck following these activities.

I am now only left with the code 681-5 code (parking brake solenoid low current).

I failed to mention sooner that I am using an aftermarket alternator from Amazon.

https://www.amazon.com/ALTERNATOR-CATERPILLAR-AGRICULTURAL-INDUSTRIAL-32868-03201/dp/B01A9HTFTK/ref=sr_1_2?crid=43UJF1SFQWSR&keywords=32868-03201&qid=1706400441&sprefix=32868-03201,aps,111&sr=8-2

I've been using this alternator for close to 50 hours without issues. Perhaps the alternator is starting to crap out and not give the right amount of voltage to the parking brake solenoid? The battery seems to stay charged so I never gave this a thought and I'm not getting any alarms or codes related to low voltage anywhere else, but I am learning that anything is possible.

Have you heard of anyone else having issues with using Non-OEM alternators? Do you know what is the minimum live voltage the alternator needs to put out for the parking brake solenoid?

Thanks,
WW

 

[Nige]

Do you know what is the minimum live voltage the alternator needs to put out for the parking brake solenoid?

If I can turn the question around, how much voltage is your alternator turning out measured at both the alternator and at the battery.? TBH I would be suprised if the voltage was way low because in that case the machine should throw up either a Level 2 or Level 3 "Low System Voltage" E875 Event.

Conditions to create an E875 Event are as as follows: -

E875 (2) - Activates when the engine is running and battery voltage is < 12.0 VDC for 30 seconds. - Deactivates when battery voltage is > 12.25 VDC for 2 seconds.

E875 (3) - Activates when the engine is running for at least 1 minute and battery voltage is < 11.5 VDC for 10 seconds. - Deactivates when battery voltage is > 11.75 VDC for 2 seconds.

NOTE: In the case of really low voltage that later increase an E875 (3) can go away and still leave E875 (2) Active.

You asked earlier about a plastic nut to secure the solenoid on the park brake valve replacing a steel one. See attached. It appears as though your machine JWF1830 was built after the change which according to the article was made at the factory from machine JWF1760 onwards.

TBH after a lot of going round in circles I am still highly suspicious of the wiring for the parking brake solenoid circuit, as opposed to the solenoid valve itself. The 681-5 Diagnostic Code relates to the entirety of that circuit, not just the coil of the solenoid, and I can't help thinking something is lurking in the wiring somewhere - especially with what you found in the speed sensor wiring (kudos for that BTW)

 

[Weekend_Warrior]

If I can turn the question around, how much voltage is your alternator turning out measured at both the alternator and at the battery.? TBH I would be suprised if the voltage was way low because in that case the machine should throw up either a Level 2 or Level 3 "Low System Voltage" E875 Event.

Conditions to create an E875 Event are as as follows: -

E875 (2) - Activates when the engine is running and battery voltage is < 12.0 VDC for 30 seconds. - Deactivates when battery voltage is > 12.25 VDC for 2 seconds.

E875 (3) - Activates when the engine is running for at least 1 minute and battery voltage is < 11.5 VDC for 10 seconds. - Deactivates when battery voltage is > 11.75 VDC for 2 seconds.

NOTE: In the case of really low voltage that later increase an E875 (3) can go away and still leave E875 (2) Active.

You asked earlier about a plastic nut to secure the solenoid on the park brake valve replacing a steel one. See attached. It appears as though your machine JWF1830 was built after the change which according to the article was made at the factory from machine JWF1760 onwards.

TBH after a lot of going round in circles I am still highly suspicious of the wiring for the parking brake solenoid circuit, as opposed to the solenoid valve itself. The 681-5 Diagnostic Code relates to the entirety of that circuit, not just the coil of the solenoid, and I can't help thinking something is lurking in the wiring somewhere - especially with what you found in the speed sensor wiring (kudos for that BTW)

Your intuition is correct. I am embarrassed to post this as the issue really was an open circuit in the wiring. When I performed the continuity test a few weeks back I thought the meter was measuring "micro" Ohms, but in fact it was showing "MEGA" Ohms so the circuit was wide open.

As Zewnten suggested weeks ago, I finally checked today the resistance from wire end to wire end on both wires and the yellow one showed to be open. I don't know where the break in the wire was, but spliced in a wire from the parking brake solenoid plug to the ECM plug. This worked and the machine is mobile again. That was a $370 mistake that I could've avoided had I listened to you guys sooner - my apologies.

At first, I wasn't able to move very far before the parking brake re-engaged. Turning the machine off and on again allowed me to disengage the brake and move again, but only for 2 yards before it locked me out again. I did this about 5-7 times before I realized I may have switched the plugs for the 2 speed sensors when I was cleaning them out. I sure did. Swapping the plugs solved the problem and I am able to run marathons.

HOWEVER - a new issue emerged today. I'm getting a code 358-5 and the arms and bucket controls are locked out. The problem grew gradually immediately after fixing the parking brake issue. At low RPMs I was able to control the arms and bucket, but increasing the RPMs triggered the flashing driver alert light and then the hydraulic interlock engaged. Lowering the RPMs made the alert light and hydraulic interlock go away. As I was cycling through the RPMs I heard some noise that resembled cavitation in a pump. This went on for about 10 minutes. Now the hydraulic interlock stays active and cycling the RPMs does nothing but burn more diesel. This issue came out of the blue and I never had any issues with the hydraulic interlock prior.

It's strange that this happened immediately after I spliced the wire and fixed the parking brake issue. All of the work done was with the negative on the battery disconnected so I don't believe I fried anything.

Do you guys know what kind of issue I may be dealing with now? Googling the 358-5 code doesn't show concrete results, but looks like it may be related to the implement hydraulic pressure solenoid? I don't know where that's located. Please share if you do.

I can start a new thread if needed.

Thanks,
WW

 

[Nige]

CID358 FMI05. A similar fault to the one you had before, except that it's in the circuit for the Implement Shutoff Solenoid. Use the attached troubleshooting procedure in conjunction with the electrical schematic.

 

[Nige]

Any chance that you disturbed something while messing with the wiring for the parking brake solenoid valve and the repair to it.?

 

[Weekend_Warrior]

Any chance that you disturbed something while messing with the wiring for the parking brake solenoid valve and the repair to it.?

I don't think I did as I only worked on the plugs for the parking brake solenoid and speed sensors. I didn't disconnect any other small plugs, but I did disconnect all of the large square plugs (the ones with 20+ wires) that I could identify to check for corrosion, but re-installed them carefully. I will try disconnecting the J2 plug again and re-installing it since that's the only thing that was removed when I made the repairs yesterday. I'm curious if I have a rodent issue. If a rodent chewed through the wiring harness would all of the alarms come in at once or would they be in a queue like what I'm experiencing? I would think the former is true since I had the speed sensor codes previously, but want to ask the question to check the box.

 

[Weekend_Warrior]

CID358 FMI05. A similar fault to the one you had before, except that it's in the circuit for the Implement Shutoff Solenoid. Use the attached troubleshooting procedure in conjunction with the electrical schematic.

Thank you for the troubleshooting guide, Nige. Looks straight forward like the one for the parking brake valve. I'll try to troubleshoot this week, but for sure during the week. The parts manual shows it to be component #2 below. I couldn't find a better picture showing the location of the solenoid, but I am certain that I did not mess with this part during my repairs. If it is truly defective, then it won't hurt the wallet as much - ~$150 for a new one from CAT.

https://parts.cat.com/webapp/wcs/stores/servlet/en/louisiana/252-4734