D5G parking brake won’t disengage

[Brycewayne12]

It started while I was operating it in reverse and when I crossed over neutral the parking brake engaged before I got it into forward… (I was actually looking at the dash and saw the light come on at that moment) after that I tried cycling the parking brake and nothing happens? First thought was maybe the switch is bad, replaced it and nothing changed. so I checked the diagnostic codes via the flashing light indicator and I got codes 255 CID 1699 forward/neutral/reverse and 256 CID 1700 position sensor (steering) both of witch are related to the joystick either getting high/low/intermittent voltage. I checked the battery with a multi meter I borrowed from a friend that wasent really for direct current the only DC option was 300V so I wasent able to get an precise voltage reading.. do I need to get the correct multimeter and make sure the battery and alternator are good before I go replacing the joystick with the controller it sets on?? I only see the light for the battery on the dash when the machine is off and I turn the key once, soon as it starts that light goes away so I don’t know if I still need to be concerned with that or not? Lastly if I do have to replace the joystick will I have to calibrate the new one? Cat wants to charge me $800 just to drive out to me so I’m hoping to avoid that if possible!

 

[Nige]

do I need to get the correct multimeter and make sure the battery and alternator are good before I go replacing

Yes. Low output from the alternator is a common cause of electrical/electronic issues on this model. Check the basic stuff such as fan belt condition, tension, etc, while you’re in there.

Post a Serial Number. It helps in finding technical information.

 

[mike holcomb]

Yes. Low output from the alternator is a common cause of electrical/electronic issues on this model. Check the basic stuff such as fan belt condition, tension, etc, while you’re in there.

Post a Serial Number. It helps in finding technical information.

Sounds like what I went thru a month or so ago. I think I would advise to check the hyd ports to make sure they have oil PSI to rule out pump coupler. Else for less experienced people they may not know how to go thru and test all the sensors.

 

[Brycewayne12]

Sounds like what I went thru a month or so ago. I think I would advise to check the hyd ports to make sure they have oil PSI to rule out pump coupler. Else for less experienced people they may not know how to go thru and test all the sensors.

are those codes consistent with the pump coupler?? What causes the coupler to fail, do you know?

 

[Brycewayne12]

Yes. Low output from the alternator is a common cause of electrical/electronic issues on this model. Check the basic stuff such as fan belt condition, tension, etc, while you’re in there.

Post a Serial Number. It helps in finding technical information.

 

[Nige]

RKG-prefix D5G. So the earlier comments regarding alternator output are most certainly valid.

You should verify the alternator output voltage and everything that might affect it such as fan belt tension, condition, etc, as a first step before you consider doing anything else.

The second step (or could be the first if you have the gauge handy) as suggested by Mike is to get it on the test ports and see if there is any pressure. No pressure anywhere - failed drive coupling.

See the thread Mike created HERE and how the conclusion was finally arrived at theat the coupling was toast. All the info regarding testing pressures is also there.

 

[Brycewayne12]

RKG-prefix D5G. So the earlier comments regarding alternator output are most certainly valid.

You should verify the alternator output voltage and everything that might affect it such as fan belt tension, condition, etc, as a first step before you consider doing anything else.

The second step (or could be the first if you have the gauge handy) as suggested by Mike is to get it on the test ports and see if there is any pressure. No pressure anywhere - failed drive coupling.

See the thread Mike created HERE and how the conclusion was finally arrived at theat the coupling was toast. All the info regarding testing pressures is also there.

I’m happy about the first half of that reply but not the second half….. and the drive coupling gives no warning that it’s about to fail??

 

[Brycewayne12]

RKG-prefix D5G. So the earlier comments regarding alternator output are most certainly valid.

You should verify the alternator output voltage and everything that might affect it such as fan belt tension, condition, etc, as a first step before you consider doing anything else.

The second step (or could be the first if you have the gauge handy) as suggested by Mike is to get it on the test ports and see if there is any pressure. No pressure anywhere - failed drive coupling.

See the thread Mike created HERE and how the conclusion was finally arrived at theat the coupling was toast. All the info regarding testing pressures is also there.

Are those codes constant with the drive coupler??

 

[Nige]

Are those codes constant with the drive coupler??

Could be anything TBH.
Verify alternator output before moving forward.

I'll find some diagnostic procedures for the 1699 & 1700 Component Codes but I would suggest that you don't go digging into them before checking that the machine system voltage is sufficient. As a condition indicator the battery voltage should be around 12.5v with the engine stopped and the alternator should be producing at least 13.5v with it running.

 

[Nige]

I’m happy about the first half of that reply but not the second half….. and the drive coupling gives no warning that it’s about to fail??

No it does not. In the case of Mike's D5G a lot of time was spent tail-chasing Diagnostic Codes and test procedures when if a pressure gauge is available it's possible to rule out a failed coupling in a few minutes. I was simply suggesting that if you have a pressure gauge it would be an easy test to rule out the possibility.

 

[mike holcomb]

I’m happy about the first half of that reply but not the second half….. and the drive coupling gives no warning that it’s about to fail??

No signs. Just came to stop and park brake light was on. I didn't realize there was a separate pump that ran the blade. So I thought pump was fine and proceeded to test and change sensors. After that still nothing next test was the hyd port test. No fluid, no psi. Coupler no good. 7800hrs on machine

 

[mike holcomb]

No it does not. In the case of Mike's D5G a lot of time was spent tail-chasing Diagnostic Codes and test procedures when if a pressure gauge is available it's possible to rule out a failed coupling in a few minutes. I was simply suggesting that if you have a pressure gauge it would be an easy test to rule out the possibility.

I'm not trying to cut in on you suggesting how to go about finding a fix. I enjoyed learning the steps to testing. Just time consuming. It was still cheaper then having cat drive out and charge 2k to diagnose. I also could've spent all month doing the coupler and it still would've been cheaper then having Cat do it lol

 

[CM1995]

Could be anything TBH.
Verify alternator output before moving forward.

I'll find some diagnostic procedures for the 1699 & 1700 Component Codes but I would suggest that you don't go digging into them before checking that the machine system voltage is sufficient. As a condition indicator the battery voltage should be around 12.5v with the engine stopped and the alternator should be producing at least 13.5v with it running.

^^This.

G series machines get weird when the voltage drops from weak battery or alternator.

 

[Brycewayne12]

I’m going to get a more accurate multi meter now and I’ll check the voltage in the morning! I see it’s divided on whether to pull the motor or slide the pump back to get the old coupler out and the new one in?? Pros and cons of both methods would be appreciated, even if it’s not the coupler this time the machine has 8500 hrs so I’m sure it’s coming! Thanks you guys have helped a lot

 

[Brycewayne12]

I'm not trying to cut in on you suggesting how to go about finding a fix. I enjoyed learning the steps to testing. Just time consuming. It was still cheaper then having cat drive out and charge 2k to diagnose. I also could've spent all month doing the coupler and it still would've been cheaper then having Cat do it lol

Could you point me in the direction of the pressure gauge I’d need to test the hydraulic ports? I’m headed out to test the alternator and crossing my fingers but if that’s not it I’m gonna need that gauge

 

[Nige]

Do you have a 500psi pressure gauge.?
Hook it up to Test post #7 (should be marked "Park Brake") and with the engine at Low Idle see what the pressure is with the parking brake switch in the OFF position. Try it at High Idle also.
Spec is 344 ± 44 psi.



If you get pressure with the park brake in the OFF position the pump coupling is OK.

 

[Brycewayne12]

Do you have a 500psi pressure gauge.?
Hook it up to Test post #7 (should be marked "Park Brake") and with the engine at Low Idle see what the pressure is with the parking brake switch in the OFF position. Try it at High Idle also.
Spec is 344 ± 44 psi.

View attachment 293269

If you get pressure with the park brake in the OFF position the pump coupling is OK.

Can you send me a link to the pressure gauge I need?

 

[Nige]

Can you send me a link to the pressure gauge I need?

Cateprillar 8T-0855 (0-600psi) but TBH any gauge with a maximum reading of 5-600psi will do the job.
The test procedure calls for a 177-7862 Hose, 2 x 6V-4143 Couplers, and a 6V-3989 fitting to screw into the pressure gauge, but that's using quick couplers at both the machine and gauge ends.

 

[Brycewayne12]

Cateprillar 8T-0855 (0-600psi) but TBH any gauge with a maximum reading of 5-600psi will do the job.
The test procedure calls for a 177-7862 Hose, 2 x 6V-4143 Couplers, and a 6V-3989 fitting to screw into the pressure gauge, but that's using quick couplers at both the machine and gauge ends.

I got the hose made up headed out there now! I had found a thread yesterday or the day before that had guys debating on what was the better route to pull the motor or slide the pump back but I can’t find it again?? You had posted the work over sheet to pull the pump in that thread I think. The majority of guys in my position went for pulling the motor but a cat mechanic commented at the end of the thread and said if it’s a G model you should go for the pump side since there’s enough room to just slide it back and change out the drive coupler. I wanted to try to get in touch with that guy to see if he had any advice or tricks that would be good to know before I tear off into it, if that’s what needs to be done? I’ll know shortly what needs to happen!

 

[Brycewayne12]

Cateprillar 8T-0855 (0-600psi) but TBH any gauge with a maximum reading of 5-600psi will do the job.
The test procedure calls for a 177-7862 Hose, 2 x 6V-4143 Couplers, and a 6V-3989 fitting to screw into the pressure gauge, but that's using quick couplers at both the machine and gauge ends.

I’ve got nothing in any of the test ports