Hey everyone, My D5G Serial# WGB03584 will not release the parking brake. It's not showing any codes on the dash. Changed out the pressure switch on the drive motor. Pulled the Solenoid and it checked ok ( 10 ohms ). Cat dealer said my rocker switch was good. When I check the voltage going to the solenoid it reads 1.3V. I am thinking it might be the ECM, I sure hope not, but if it is, bite the bullet and get back to work. Any thoughts.
Was it working when the parking brake came on..? By that I mean was the machine moving and came to a grinding halt..? Does the parking brake indicator light go out when you try to release the brake, even if the brake itself doesn't release..? If the solenoid resistance checks out OK have you tried removing the valve body to determine whether or not the poppet inside it is stuck..? Even a small speck of dirt is enough to cause the ball to hang up.
Yes it was working fine. I was pushing a full blade and it just stopped. The parking brake light never goes off. I haven't tried the poppet yet but I will. Thanks Nige.
We had a similar problem on our D5G last month. Dozing with full blade and machine comes to a complete stop, won't engage afterwards. Checked the voltage on the batteries and one was weak. Check voltage on alt. and output showed 13.8 volts with system charging. Swapped the alt. out and we haven't had the issue since. Our problem started intermittently and then 3 times within a 4 hour period. The G series dozers are very finicky about proper voltage for operation. The reman. alt. from Cat was $290, the core charge was $293.
Based on CM's experience I would say check your battery voltage and alternator charging function before you start pulling the valve out, even if it's only to eliminate a possibility.
We have plugged up to the machine with a lap top and all voltages seem good.
Try reading the battery voltage with a digital multimeter while the engine is running at low idle and post the results. You mentioned above that the dealer told you the rocker switch (I assume the park brake switch) was good. Just exactly how did they do that..?
Ok I will. It will take me a little while to get back with you, no service where the machine is.
Should I have hydraulic pressure on the pumps behind the engine even without the Park brake working?
They checked the PB switch with a multimeter and when we plugged up the lap top it showed engaged and disengaged respectively.
It showed 14.4 volts at idle.
Scratch that idea then, 14.4v is fine. A thought. Have you checked the pilot override solenoid/valve for correct resistance and/or functionality..?
Just via lap top, haven't check it with a meter. Yet.
I checked the hydraulic pressure on the rear drive motor where the PB pressure sensor goes and I have zero pressure. Should that be telling me something?
The over ride solenoid working good. 10.0 ohms, and it appears to be work properly.
Check the voltage at the pilot override and park brake solenoids when the park brake is off and compare the 2 values.
Could be a pump drive coupling failure. Does anything work on the hydraulic system. Is there any pressure anywhere. I think this has the nylon pump drive that is a common failure.
Got any ideas anybody? I am stuck, don't know which way to go. Please help.
We know you can't get it into gear but do the blade hydraulics work..?
Could be a bad coil? I have run into a few lately.
Hi D5GDevo A couple of things to look at .The ECM controls the park brake solenoid and the override solenoid according to inputs to the ECM Any of the items listed above can cause your park brake to stay applied. one that may not show a fault is the service brake limit switch also you said that you had no faults in the dash did yo check the LED fault light in the fuse panel? you can check your codes without ET by this method you may have a broken drive plate which is some type of nylon, the rear pump supplies charge pressure to release your park brake. to check your charge pressures use the test ports shown
using the implements wont give an indication of drive condition because the implement pump is driven of the right hand side of the engine
Just to let everyone know what was wrong with my machine. I had to pull the engine and replace the nylon flange and hub that drives the hydrostatic pumps, it was stripped out. No electrical problem at all. Thanks for everyone advise and help.
These guys here are the best ............Hats off to all
How do I determine it’s the drive plate before I pull the motor I have a d5g doing the same thing
Define "the same thing" please. Do you mean the park brake won't release.? Always good to start with a Serial Number. Question: Do you know how to access Diagnostic Codes on the machine.?
Sorry about that the break want release and we have no pressure on either hydraulic filter just trying to find a way to test the drive plate before we pull the motor
Take a look at the illustration in Post #22 above. There are two test points (#3 and #7) circled. If you have no pressure at those two test points then the drive coupling between the engine and pumps has failed.
How do I take the front hydraulic pump off on the right hand side of motor what do I need to do first
Why would you want to do that.? The pump on the front RH of the engine only works the blade hydraulics. It’s nothing to do with the drive system or the park brake.
just trying to get the motor out to replace drive plate
What's the S/N of your tractor.? I'll post up the complete procedure for replacing the coupling. Be aware that the engine comes out complete with the drive pumps which are then split off afterwards to allow access to the coupling.
How do I remove the air duct to get bolts out to take the engine out
See my post above. Still waiting for a S/No.
Brady I would suggest you follow Niges advice and post of a serial #. You are in good hands following his advice.
Mhk18225
That's the engine but never mind. The tractor is RKG03212. Attached the procedure for removing the engine and pumps as an assembly to get you going. I'll post up more in a bit.
Thank you
So here is the coupling. The hystat drive pump is mounted on the back side of the Plate #3 and the coupling is on the front side. The two eyes on the back side of Plate #3 are the rear engine mountings. This is why the engine has to come out, even with the drive pump removed in the machine there is no access to get at the coupling #1. I suggest while everything is disassembled that you check the Coupling Hub #2 is tight on the shaft. I seem to recall at least one case where the hub had slipped along the shaft and as a result the splines had disengaged from the coupling. It's a split hub that clamps to the shaft with an Allen bolt.
Thanks will let you know it need any other help really appreciate
Here's the engine installation instructions. That ought to complete the set.
Just got motor out and it was indeed the drive plate thanks for the help now gotta put the drive plate back in it and put the motor back in and will be back to work thank you
In a weird way I'm glad to hear that the problem was the coupling. It's always a leap of faith to start pulling the engine out of a machine just on the basis of the say so of some random person on an internet forum.
Yelp i knew it was more than likely that because drive pump didn’t have pressure
think you could send me a document on reinstalling the engine now
Go back up about 4 posts and you'll find it.