Code PO404?

Hello, what sub model is the Fuso? FE125, fe145, fe180, fg140, etc? I do not see any 3.0liters listed. We actually don't have any information listed on this vehicle here in the US. But if you have a loss of power and an EGR code. It sounds like the EGR valve is stuck open. Try unbolting the EGR valve and make sure there is no carbon build up holding the pintle open. I will try to find a picture of the valve for this vehicle, but that that's where you should start. Even a small piece of carbon can hold the valve open, allowing exhaust gases into the intake manifold all the time when it's only supposed to open under heavy throttle.
This is a picture of the valve; I hope this is the correct one. The code criteria state the ECM (engine computer) is reading an improper voltage through the valve. So, this may be a faulty valve.

This type of valve uses stepper motors to control it. A stepper motor has 2 sets of windings internal and 4 wires, 2 wires control each winding to move the valve in or out as needed.
If this is the valve you have on your vehicle, it should be a 4-pin plug on the valve, if so, you can check the resistance across the 2 windings with the valve unplugged to check if one of the stepper motors windings has lower or higher resistance than the other. Unfortunately, since this vehicle is not sold here in the US, we have limited to no information on it.

Okay, well it's not listed here on All Data so I'm looking some other places for European model vehicles. Are you sure it's not an 8 wire EGR valve, I came across some diagrams that are showing 3 wires for the motor inside and another 5 wires for an internal sensor. I'll post what I found so far. Let me know if any of those wire colors match up to what you have.

And what color are the 2 twisted wires?

For future reference, I came across this site. It's filled with information on this model, there are service manuals you can download and pretty extensive amount of information. Wiring diagrams, network info, etc.
https://truckmanualshub.com/mitsubishi-truck-service-repair-manuals-pdf/

Does your scantool have any live data options?

I haven't found any other diagrams so far, does the turbo have to come off to get to the EGR valve? The service manuals for these vans are over 2,000 pages. Some of the setups I'm seeing have EGR coolers with built in sensors, and multiple EGR valves. The EGR valves also have temperature sensors as well. I'll post a diagram if I can find a 6-wire valve.
I found a five wire EGR valve, which looks like it might have two wires for the valve together, possibly twisted. And the other three wires look like a position sensor, where pin 5 is a positive voltage with pin 4 being the signal and pin 3 being the ground so that pin 5 id think that would be a 5-volt reference. And the other positive wire (pin2) is most likely going to be a 12-v feed (EGR pos) and pin 1 (EGR neg) for valve movement.

I havent found any other diagrams so far, does the turbo have to come off to get to the egr valve? The service manuals for these vans is over 2000 pages. Some of the setups Im seeing have egr coolers with built in sensors, and multiple egr valves. The egr valves also have temperature sensors as well. Ill post a diagram if I can find a 6 wire valve.

This diagram has the same 5 wire EGR valve. Same wire colors. So, on the 2 twisted wires, the blue wire with the black stripe should be the positive wire for the EGR valve (pin 2), being a positive wire, and i'll assume this is a 12-volt system. That should have battery power on it with the key On. The red wire with the black stripe is the negative for the valve (pin 1). The valve is probably a ground side switched. Does that tube on the valve go to a vacuum line running to the Intake manifold?
The other 3 pins are for the EGR valve position sensor, which is just like a potentiometer. Pin 3 is Ground (violet wire), pin 4 is Signal to ECM (yellow with black stripe), and pin 5 is going to be some Reference voltage (orange wire). I don't know this system, so it can be 5volt, I've seen some 8-volt references before. But with the key On, and your meter negative lead hooked to battery negative, you can check to see what voltage you get on pins 2 and 5.
But this diagram has the exact wire colors in the correct places. Hope this helps. It was very difficult to find any information on this van. As I said, the service manual is over 2,000 pages.
Do you have a picture of where the hose comes from that goes to that tube on the valve?

Okay, I'm just wondering if that tube has a vacuum source and there's a built-in solenoid that actuates the EGR valve, and that's what the 2 twisted power and ground wires are for.

I wouldn't condemn the ECM yet, do you have any freeze frame data with the p0404, if so, does anything look out of place. You obviously have a good idea of what you're doing by the testing you've done already. But I never replace and ECM without finding out what caused it to fault. You might want to try load testing the 12volt supply. We are extremely limited on information on this vehicle, so I don't know if the 12-volt supply for the motor comes from the ECM or from a fuse panel. I would trace down the wiring first to see if there are any corroded connectors the wiring runs through. Doing the bench test, you're giving the valve 12volts from a source that obviously can provide enough current to actuate the valve, but its regular supply might not be able to, since this is a performance code. If you erase the code, does it come right back or does it need to drive under conditions where the valve would be activated?
If you have a scope or can graph the position sensor in the valve, I would erase the code and take it for a ride while monitoring the valve's position when the code sets. To see if the valve is not opening when it should, and if there is some voltage drop on its supply. If it's a pulse width modulated ground-controlled valve, there could be a bad ECM ground not allowing full control of the valve also. Duplicating the issue and catching it in the act is the only way to see what the valve is losing. Check the resistance across the motor pins as well. Maybe it has low or high resistance. The bench test wasn't a pwm test, it was a full-on power test.

That resistance sounds super low, at 0.1ohms you would be getting 120amps of current flow through the motor, there is probably a current sensing circuit inside the ECM and is coding that valve right at key on during some possible self-test, but that definitely sounds too low. When the valve is not active, having no ground you're reading the supply voltage through the motors coil, the ECM is intentionally shutting down the circuit to protect itself from such high current flow, hopefully it didn't damage the ECM driver for the valve.