ZX35-2 Hitachi High Idle won't come down

[Serge D Paquet]

The high idle won't come down, I tested the alternator with a multi meter and it the voltage goes everywhere, it's not steady. Could it be that i need a new alternator. I tested the alternator with the battery disconnected. I think that the voltage should be around 13.7 or so. I'm I right ?

 

[mg2361]

I tested the alternator with the battery disconnected.

Did you take the alternator somewhere to be tested? You test the alternator with the battery connected. Never disconnect a battery on a running engine. Define not steady. What is the voltage output of the alternator?

The high idle won't come down

Has the throttle dial voltages been checked? Is the "SYS" light on, or blinking?

 

[Serge D Paquet]

The voltage of the alternator with the battery connected is 14.02 , The sys red light is on and flashing. Is the flashing light mean something ?

 

[mg2361]

The voltage of the alternator with the battery connected is 14.02

That is good charging voltage. Now connect a meter set to AC voltage (yep, I said AC) across the battery terminals to see what you have. It should be less than 0.5V AC. This test is to make sure there is not any AC voltage leakage from the diodes which can play he** with any computerized system.

The sys red light is on and flashing. Is the flashing light mean something ?

Yes, that light is on or flashes if there is a problem with the throttle control dial potentiometer, engine auto-idle controller, throttle cable actuator motor, or wiring harnesses & connectors/terminals between these components.

I PM'd you.

 

[Hayman786]

Mg2361
I see this is an old post but it looks like I have the same issues.
Start machine it goes straight to medium idle. At some point the machine goes to high throttle and stays high with no input from throttle knob.

HITACHI

Model ZX50UNA2

Pin FF01MCQ244670

What I have done
Replaced throttle actuator
Olm and load tested all wires that originate at 6 pin doich? Connector to the 12 pin connector under the seat.

Cleaned all connectors I took apart.

Tested battery a/c=.01 d/c 14.3

I am stuck. What more do you think I should check?

 

[machinerepairman303]

i recommend you to check below coditions

air intake sensor is damaged and the too much air intake.
1.water temperature sensor is faulty, increases the idle speed to increase the vehicle water temperature.
2.throttle position sensor is faulty.
3.water temperature sensor is damaged.

 

[Simon C]

When testing for alternator AC ripple voltage, it is better to put the Red test leads on the output-hot big cable of alternator and the black lead on good ground. If both test leads are put on the battery, it can act as a sink and not show the actual amount of ripple voltage. This is the information that I have from Fluke, but maybe I am wrong.
As mg2361 said 0.5 AC volts is the maximum you want to see.
Simon C

 

[Hayman786]

Machine repairman303
I think the throttle Controle nob is the culprit. I went into the local Pape shop (John Deere dealer) they printed off some test parameters I back probed the 3 wires coming from the throttle Controle.
I got the 5v that I needed from one wire and no voltage change on the other wire when the nob is moved.
Simon C
Thank you for that clarification when I can get back to my shop I will retest.

Thank you both.

 

[mg2361]

I see this is an old post but it looks like I have the same issues.

Check your messages.

 

[Hayman786]

Mg2361
Thank you the first download Pape printed off for me I did not have the second download. Thanks again.

 

[mg2361]

Which one don't you have (throttle dial troubleshooting)?