Here goes my usual reply, use the search function and look for posts by rodbolt on precision blend, he has covered trouble shooting various models a thousand times now, follow his instructions, do not guess and assume, it is simple, and don't buy a new ECM.

I have done that and that is how i got to this point. All other parts of the systems seem to be OK.
Remote switch checks OK
Engine switch checks OK
Pump runs using manual switch and if 12v put to the pump.
Started engine and jumped blue/green wire to black wire. nothing happens (pump should have run).
Drained engine tank to near empty, turned key on and nothing happens.
When testing continuity I got to the EMC and when i removed it i found the crack in the back of the case so i made the post looking for answers!!!

and yet you wont look for my poor battered posts.
I get really really tired of posting on a stupidly simple system.
there are 4 switchs that are either ON or OFF, just like the light bulb in your fridge.
have you actually tested for 12V between the blue and brown wires at the pump with either the engine oil tank drained or the manual switch depressed while the key is on?

odds are high your ECU is fine.
in 20 some odd years of working with yamahas I have seen maybe 3 ECU failures.

do you have a real tach or the standard bass boat faria/Teleflex crap?

Rodbolt17,
I HAVE LOOKED AT ALL of YOUR POOR BATTERED POST - all of the ones that i could find!! That is what I said in my previous post, and that is how i got to the point of the EMC. I believe that i have run ALL of the tests that i have seen you refer people to. I also have studied the shop manual to exhaustion (which is a little confusing because they cover everything from early systems to 3 LED systems to the digital system and in HP from 2-300 all of which appear to be different).
To answer your questions:
1. With the engine tank very low and the key in the on position, there is 0 volts from the blue to the brown wires at the pump.
2. When the emergency fill switch is depressed there is 12v (and the key on).
3. I have a Yamaha digital tach with 3 bars not some crap aftermarket.
I'm sure that you get tired of continuing to answer questions on a simple system (it is simple to you who work on them for a living) but it is not so simple for someone who gets faced with an issue once every 5 or 10 years. Sorry but i had to complain!!!

Rodbolt has wiped his ass for so long now that he can't remember the time when he did not even know where it was, let alone how to wipe it. It took many many times of his shitting in his pants before his mamas message got through to him. There was a time when she felt he would never get it.

Measure the voltage from the yellow wire at the point where it connects to the brown pump lead to a good ground point on the block. With the key on of course. You should see 12 volts and I will bet that you do. The blue wire is only grounded when you activate the toggle switch or the ECU does it.

Have you checked the wiring from the boat tank sensor switch all the way to the ECU and also to ground? If the ECU does not sense that the switch is closed (grounded) then the auto transfer system won't.

Same with the wiring from the main tank sensor switches. If the ECU does not see a ground telling it that switch SW2 is closed then the auto transfer won't.

The motor has to be running for the auto transfer system to work. With one exception. If the main tank is empty and the remote tank is full, then when the key is turned on the pump will run for three minutes or until the main tank fills up, whichever happens first.

Boscoe,
This is going to be a long answer but here is what I have in response to your questions:
1. I have 12v (key on) from brown (at the pump) to ground; blue is open to ground.
2. I have continuity on all wires from to the same wire at the ECU; the brown and black wires have continuity to ground, the blue wire is open to ground, and the black/red stripe wire has 3500 ohms to ground - SHOULD THIS BE?? The key is off for all of these readings as i had to disconnect the ECU to get to the wire pins in the 28 pin plug.
3. From the main tank switch (unplugged at the connector) to the EMC plug i have continuity for all wires and all are open to ground except the black does have continuity to ground (ECU is still unplugged for these reading also).
4. On the switch side of this same connector i have continuity from the black wire to both blue/red wires but no continuity for to any other wires for the blue/green or the blue/white (ECU still unplugged and the engine tank at very low level.
Does this help and what does it tell you??
Thanks

3500 ohms is way too much. The ecu may be seeing that as an ungrounded (open) circuit in which case the auto transfer mode is inhibited. The ecu thinks the remote tank is low on oil so it stops the automatic transfer.

If the black wire to the sensor switch checks OK, but the black/red wire to the ecu has excessive resistance I would check the oil harness connectors for corrosion or other signs of distress.

ok
at key on what does the tach oil indicates do?
should self test then display the far right bar.
if it displays a center bar it wont transfer automatically until SWB or the SWB circuit is repaired.
SWB is the switch in the remote tank. closed when oil level is sufficient for transfer.
open and NO automatic transfer AND the center bar lights.
you can also verify the ECU "sees" SWB closed, or open, with the lap top.
there is a splice on the black/red wire from the remote tank where it turns to green(or Green/white) heading to the tach and to typically green/black heading to the ECU.


a quick test, simply drain the engine tank, turn the key ON.
look at the tach.
you should have an audible and 3 bars flashing.

if you don't have 3 bars flashing check the SWB and associated wiring.

all SWB does is sit there and tell the ECU if there is sufficient oil for automatic transfer. remove the ground (open switch or circuit) and the tach sees the open and illuminates the center bar and the ECU sees the open and inhibits auto transfer.


if SWB passes the flasing bar test,make sure the remote tank is about 1/2 full, then on to some VOLTAGE testing.

with the remote tank about 1/2 full and SWB is known good as well as the circuits here is what happens.

when you drain the engine tank SW3 closes.
SW3 is the lowest switch on the engine tank.
SW3 commands the second transfer on command as well as setting the audible command and setting the far left bar on the tack via the green/red.

now IF the ECU 'sees' SW3 on AND SWB on it assumes 1 of two things.
1 is its an initial engine tank fill or 2 the system malfunctioned.
the ECU responds by applying a ground path via the blue wire from the ECU to the transfer pump.
this ground path will be applied for 180 seconds.

this is your test window.

have the meter set up from brown at the pump bullet connector to the engine block, pump connected.
anytime the key is on this should display battery voltage.

if this test passes on to the blue wire.

either use the manual switc ECU side bullet connector OR find the transfer pump blue wire at the ECU and back probe it with a paper clip.
now set the meter on the DC scale of at least 15V.
one lead at the pump blue wire bullet connector.
the other lead at the ECU blue wire.
turn the key on,you should have an audible and 3 bars flashing.
the meter should show less than 1/2 Volt within ten seconds and remain that way for 180 seconds.
if it shows battery voltage then the ECU ground is working and you have lost circuit continuity on the blue wire.

see what I mean, its a dirt simple circuit that employs 4 switchs.
SW1 engine tank switch all the way up, commands pump off.
SW2 switch in the middle position,commands pump ON.
this switch simply bounces from SW1 to SW2 and back all day long, until something goes horribly wrong.
SW3 is the lowest switch,when closed commands pump on, commands RPM reduction,commands audible and grounds the circuit to illuminate the tach far left bar.

the ECU responds to SW2 or SW3 by applying a ground path on the blue wire between the transfer pump and the ECU.
if SWB is OPEN, or the circuit compromised, the ECU will NOT respond to SW3 or SW2.
however all alarm functions will work.

remember the ECU does NOT control the tach visual indicates, tach indicates are con*****ed by SWB and SW3 ground paths.
remove the ground from SWB, or unplug the connector at the remote tank, and the tach illuminates the center bar.

the ECU does monitor the switchs.

hope this helps.

What I am wondering is if the ECU might see 3500 ohms as an open switch while at the same time the tachometer might see this as a closed switch?

I wonder too much sometimes. If I had a motori with a tachometer, and a 3500 ohm resistor, I would test it to see what happens.

Make that 1001 times now!

***!!!
Now that is a lot of very good information that i can walk through. It is also a much better explanation than i found in previous post here or in the service manual!!
Thanks a bunch and i'll let you know what i get as i walk through these steps.
VERY VERY MUCH APPRECIATED!!!!

whaddya mean?????
sheet I have posted on this site and another so much on a stupidly simple 4 swictch circuit I am about ready to do the poo poo dance.

like my wifes stupid toy Yorkie.

Boscoe, you you have to remember the ECU does NOT control the tach visuals.
its a key point.
however on the Z and VZ motors you can watch SW1,SW2<SW3 and SWB on the laptop.
that's what the ECU tells the laptrop it "sees".
after that its a gravy train.

I know that the tach does not control the oil system status lights. SWB controls the green/yellow light or the right hand/middle icons while at the same time telling the ECU that the switch is either open or closed.

A closed switch SWB in theory should have zero resistance to ground. It is when there is something else amiss in the circuitry that might cause a closed switch to appear as being either open or closed, depending upon how the system is designed.

Might the ecu see 3500 ohms and see the switch as being open even though it is closed? Might the tachometer see 3500 ohms and see the switch as being closed? If so, auto transfer would be inhibited but the lights/icons would indicate all is well, when it really isn't.

A good service manual would have laid all of this out for the user.