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Hitachi zx225uslc throttle not working

excavator

Senior Member
Joined
Oct 16, 2006
Messages
1,445
Location
Pacific North West
I've had them with a bad diode in the alternator not allowing the battery relay to turn off but they were all dash 5 or earlier. I also had a ZX230 that would not shut off with the key, it had a small wiring fire down behind the batteries that melted all the wires in the harness together. The amazing thing was it did not blow any fuses.
 

Martin Canuel

Active Member
Joined
Nov 16, 2019
Messages
31
Location
Prince George, British Columbia
I've had them with a bad diode in the alternator not allowing the battery relay to turn off but they were all dash 5 or earlier. I also had a ZX230 that would not shut off with the key, it had a small wiring fire down behind the batteries that melted all the wires in the harness together. The amazing thing was it did not blow any fuses.

Interesting.. so this diode in the alternator i assume is not replaceable/serviceable.. has to be replaced with the alternator?
So check harness to the alternator then?
 

Martin Canuel

Active Member
Joined
Nov 16, 2019
Messages
31
Location
Prince George, British Columbia
Ive read that welding on the machine can cause alternator diodes to get fried. That being said we just welded catwalks on the machine and a thumb prior to that, we used the night switch as our battery disconnect. Maybe the 2 events are related..
 
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Martin Canuel

Active Member
Joined
Nov 16, 2019
Messages
31
Location
Prince George, British Columbia
I was finally able to get someone to shut of the machine while i watched the servo motor. When shutting down the engine you can hear rpm drop/ sputter a bit to a lower rpm. Watching the actual motor it barely actuates the throttle when shutting it down. Iam going to adjust the throttle cable some more manually and see if that solves my issue.
 

Martin Canuel

Active Member
Joined
Nov 16, 2019
Messages
31
Location
Prince George, British Columbia
OK adjusted the throttle cable while machine was running and took the idle right down to almost a sputter, then ithgtened it up and used key to turn off, barely made the rpm drop when i hit the key off.. engine relearn ? also when i had the servo motor disconnected initially there was about a inch of play in the throttle cable,. when i attach the servo to the arm do i pull out all the slack and tighten it>?
 

Volvomad

Senior Member
Joined
Jul 13, 2011
Messages
476
Location
Ireland
If there is an inch of freeplay in the system (not moving injection pump lever) I would think that is your problem
 

Martin Canuel

Active Member
Joined
Nov 16, 2019
Messages
31
Location
Prince George, British Columbia
If there is an inch of freeplay in the system (not moving injection pump lever) I would think that is your problem

Well after all of that, replace servo motor, pulling interior dash apart to test wiring, testing all the sensors, took your advice and replaced the throttle cable and wouldnt you know it a new throttle cable from servo to inj. pump fixed all my issues!!! I do thank all of you for the trouble shooting help i truly appreciate it and it actually helped me learn alot about my machine.
 

Martin Canuel

Active Member
Joined
Nov 16, 2019
Messages
31
Location
Prince George, British Columbia
Well guys its doing the exact same thing again
1- wont shut off with key
2- dr.zx wont communicate
3- no servo sound or motion with key on
4- must use manual throttle kill to turn off machine
5- servo motor, throttle cable have been replaced.
 

Martin Canuel

Active Member
Joined
Nov 16, 2019
Messages
31
Location
Prince George, British Columbia
Not so much to say a win.. i did some more diagnosing, everyone is saying to check the 5v reference circuit . i did find one pigtail of a sensor on the pilot valve that was broken, replaced it and i havent had the issue again (fingers crossed). So it hasnt acted up since but now i have a issue with my thumb only working one way.
 

Alim_ZX460

Member
Joined
Feb 22, 2024
Messages
5
Location
France
Occupation
Maintenance
Well guys its doing the exact same thing again
1- wont shut off with key
2- dr.zx wont communicate
3- no servo sound or motion with key on
4- must use manual throttle kill to turn off machine
5- servo motor, throttle cable have been replaced.
Hello, sorry I peak french, dr zx wont communicate. try this : Disconnect and connect battery ground. And connect dr zx.
 
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