2008 DF90 won't start.

[knagy20]

Since I know nothing about this motor, I have to ask where was the places you checked the voltages?
right at the ECU?
were the wires hooked up to those terminals when you did the tests?
Did you test without them hooked up?

can you test the voltage to the ECU or relays during cranking to see if it also is dropping?

where are you placing the negative lead of the meter during the testing?

I have the 44 pin testing connector and I'm hooking it up as the tests indicate. Black wire has gone to pin 30, the negative terminal on the starter or random bolt on the motor. I've done the tests several times with the ground in different places and the results were all the same.

I haven't checked for voltage drop to the ECM, but will. Will have to figure the relay wires out to try to test them.

Also, you are making me think. I was just looking at the wiring diagram again. I've disconnected just about everything from the motor that I can and still have it run, except for 1 thing. I added the Suzuki interface this spring so I can have digital gauges on my Lowrance unit. I have never unplugged that from the motor during any of this. Do you think that is a possible cause. I currently have no power or ground wires hooked to the battery from the fuse block that services the NMEA2000 system and my MFD?

 

[lakensea]

You are headed in the wrong direction. Study the service manual and wiring diagram closely to learn how the system & gray wire circuit works, and where the problem may be.

As far as the interface, you would have had to disconnect it in order to use the diagnostic program.

Where is the physical location of the interface module?

 

[knagy20]

I did, but I'm the type of person that if I don't replug or return something right away, I'll forget. So as soon as I unplug the computer, I've been plugging the interface module right back in. I've never tried to start the motor with it unplugged.
The actual module is in the center console.

 

[lakensea]

The reason I asked about the location is early on we had some that were installed inside the engine cowling with the network backbone starting there and we were getting some RF interference that was causing symptoms similar to your initial issue, but never complete shutdown.

Nowhere in the troubleshooting does it suggest low injector voltage is indicative of bad ground or low battery power. I think that's a rabbit hole.

I can't say for sure where you problem is, I've got a good idea, but I hate being wrong. Follow the diagnostic result, study the wiring diagram, then open your eyes and look.

You seem pretty smart - just use your head, and not necessarily the internet.

 

[knagy20]

Gotcha. Thank you.

 

[99yam40]

I was just getting at low voltage to injectors only during cranking, and I would make sure the voltage into the system was good while cranking to eleminate that kind of problem.
I have no idea, but a bad connection of either positive or negative can cause low voltage while under heavy load to other places too