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Fuse blowing

M

Mikeyp756

Well-Known Member
Joined
Mar 31, 2019
Messages
71
Location
Louisburg nc
on my hitachi ex120-2 The fuse for the ec motor blows as soon as I turn the ignition key on. I traced the wires from that fuse to the ec relay. They all seem ok. I tried the wiper relay in place of the ec relay but still blew fuse. next to the wire at the fuse is a thick red wire which looks fine, I traced back to the ignition switch. Can the problem be in the ignition switch?
 
007

007

Senior Member
Joined
Dec 28, 2016
Messages
282
Location
Australia
No will not be ignition switch.
The fault current will be caused by something down stream of the EC relay.
If that circuit diagram is correct that relay is supplying power to the that power controller card.
It is not normally easy for that card to create a short so the most logical place i would start looking was down stream around the ec motor on the engine.
If you unplug that wiring loom at the card or down at the motor and try again with new fuse.
if the fuse does not blow you just narrowed down where the problem is.
 
M

Mikeyp756

Well-Known Member
Joined
Mar 31, 2019
Messages
71
Location
Louisburg nc
007 said:
No will not be ignition switch.
The fault current will be caused by something down stream of the EC relay.
If that circuit diagram is correct that relay is supplying power to the that power controller card.
It is not normally easy for that card to create a short so the most logical place i would start looking was down stream around the ec motor on the engine.
If you unplug that wiring loom at the card or down at the motor and try again with new fuse.
if the fuse does not blow you just narrowed down where the problem is.
Click to expand...
Thanks guys, what I might have forgot to mention was if I plug in Ec motor and unplug the Pvc the fuse doesn’t blow.
 
007

007

Senior Member
Joined
Dec 28, 2016
Messages
282
Location
Australia
What are you calling Pvc? [Power motor motor relay]??
The board in the middle of the circuit appears to have a fuse for each of its functions.
So the fuse that is blowing is probably only to do with the EC Motor.
When ignition is on power is available to the top of the ec motor relay through the fuse that blows.
The power motor motor relay card below then energizes the relay above and allows power to flow into the card which is then used for the ecmotor which comes out further down on bottom right.
So you need to disconnect the ec motor but leave power on the card and relay.
If the fused dose not blow the problem is probably in the ec motor.
These motors will have very low ohm wingdings even when good, so they turn into a short very easy if they over heat and burn the coils.
A good multi meter can be used to check them.
 
M

Mikeyp756

Well-Known Member
Joined
Mar 31, 2019
Messages
71
Location
Louisburg nc
007 said:
What are you calling Pvc? [Power motor motor relay]??
The board in the middle of the circuit appears to have a fuse for each of its functions.
So the fuse that is blowing is probably only to do with the EC Motor.
When ignition is on power is available to the top of the ec motor relay through the fuse that blows.
The power motor motor relay card below then energizes the relay above and allows power to flow into the card which is then used for the ecmotor which comes out further down on bottom right.
So you need to disconnect the ec motor but leave power on the card and relay.
If the fused dose not blow the problem is probably in the ec motor.
These motors will have very low ohm wingdings even when good, so they turn into a short very easy if they over heat and burn the coils.
A good multi meter can be used to check them.
Click to expand...
Thanks 007. pvc -pump and valve control. Could the ec motor be bad even if the LED is flashing?
 
jonno634

jonno634

Well-Known Member
Joined
Dec 19, 2018
Messages
141
Location
Garfield, WA
Occupation
Farmer
Hook a light bulb in place if the fuse... you can then wiggle wires and see if you can make the light go dim... bright means short, dim, means ok.. but will make it so you can troubleshoot without replacing fuses.
 
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