CAT D4G Starts but does not move

1. #1Tyler d4c2020-02-03 22:37

   If it's a hystat and quit all at once the plastic pump driver plate most likely failed

2. #2JuanSpringCat2020-02-04 11:38

   how do I know?

3. #3JuanSpringCat2020-02-04 17:30

   Can someone please share the electrical schematics of D4G (cat00d4gJ FDC00364). It does not move forward nor backward.

4. #4JuanSpringCat2020-02-04 17:30

   The engine starts and blade moves, but park brake light is ON, it does not release.

5. #5Tyler d4c2020-02-04 17:31

   Need to see if the pump is turning at all I'm not sure where to see it at all I'll do some research

6. #6Mobiltech2020-02-04 18:31

   On a d5 i think you lose blade lift too when the coupler fails. Not sure if the d4 is the same.

7. #7partsandservice2020-02-04 20:02

   The hydraulic pump for blade is on the engine accessory drive. Blade functions will operate with striped drive plate. Park break light stays on because there is no brake pressure , because the drive pumps are not turning. Remove or slide forward the engine rather than drive pumps to avoid contaminating the drive system. That method has been mentioned on the HEF before and I use it as well.

8. #8Tyler d4c2020-02-04 20:06

   You should still have the blade working as the pump is ran off the timing gears on the engine

9. #9Ronsii2020-02-04 20:13

   HeavyEquipmentForums

10. #10Mbar2020-02-05 06:58

    Just dealt with This. Open door on right side of machine and check pressure on taps 3 and 4. Should see around 350 psi. That is front and rear charge pressure. If not charge pressure it’s the coupler. Like said above implement pump runs off from cover. Pull the cover and boot off the drive joystick. Had one rub the wires into and gave exact symptoms of a bad coupler. Make sure you have good working gauges when checking for pressure or it can Lead you down a bad path.

11. #11Nige2020-02-05 08:05

    See post #11 above and follow it to the letter. I PM'd you the appropriate electrical schematic.

12. #12Tyler d4c2020-02-05 09:56

    Small side note you may have to hook up the test lines on this 5g I have apart some are disconnected and capped so make sure there hooked up

13. #13Nige2020-02-05 10:03

    +1. Why disconnect a leaking test line when you could probably fix it just as easily.?

14. #14RTSmith2020-02-05 11:03

    I have also seen this same set of symptoms when a rat or squirrel chewed through some of my wiring harness......

15. #15Tyler d4c2020-02-05 17:41

    No clue that's how it was when it showed up here