Calling Rodbolt - F50 Relay

[boscoe99]

Rodman, need your thoughts.

F50TLR Fuel Injected Model

It appears that on this motor the relay applies battery power to the fuel pump to operate the pump. The pump is permanently grounded. Is this your understanding? Assbackwards from Yams modus operandi to ground the pump to make it run.

The relay appears to get power from the tachometer green wire. Any idea why this is?

Anyone else feel free to review the relay and let me have your thoughts please. Good, bad, ugly.

[fairdeal]

I was also surprised - and somewhat chastened -
to see that departure from "low lights the light" (or whatever Rodbolt calls it)

as for the green tach wire -
I raised that question here some time ago - don't recall that it was addressed

my F225TXRD has the same arrangement

my guess is that it holds the main relay closed -
after the keyswitch removes it's power
to allow the ECM to arrange for "an orderly shutdown"

[pstephens46]

I was also surprised - and somewhat chastened -
to see that departure from "low lights the light" (or whatever Rodbolt calls it)

as for the green tach wire -
I raised that question here some time ago - don't recall that it was addressed

my F225TXRD has the same arrangement

my guess is that it holds the main relay closed -
after the keyswitch removes it's power
to allow the ECM to arrange for "an orderly shutdown"

I’m starting to think horses may be make more sense than these motors. And I don’t know sht about horses. Yet...

[pstephens46]

Thankfully horses are not designed by the apparent Modular Team Engineering groups at Yamaha.

oops, Fing up up Boscoe’s thread...

[99yam40]

question is, can you believe the prints
seems we found a few problems with pints not that long ago on a thread
I tend to believe fairdeals theory that ecu needs to keep power to set motor up for next start and then turn off the motor even with key already in off position

[fairdeal]

I tend to believe fairdeals theory that ecu needs to keep power to set motor up for next start and then turn off the motor even with key already in off position

we always ask "did you hear the ISC clicking after you shut it down"
can't "reset the ISC" without it having power

but I suppose I could put a DC voltmeter on the tach lead,
to see exactly what is happening at that point...

[boscoe99]

Hmmm. Some interesting theories.

The tachometer green wire input needs AC voltage. Tach won't work with pulsed DC. Have not tested a green wire output from an ECU but gotta believe it is an AC output.

AC to a relay control circuit via a diode I can somewhat understand. Emphasis on somewhat.

The ECU gets power via the yellow wire from the key switch. The green wire output from the ECU is dependent upon the yellow wire input. Those electrons are fast. As soon as the key switch is opened all power to the relay and the ECU is terminated. Just as quickly the green wire output is terminated.

Confused. Yes Virginia, it is stupidly simple. But then so am I.

Damn Yamaha and their lack of theory.

[fairdeal]

To make it even more interesting -

there was a change made on the 3.3 F225 from pre-CL to CL

here is the ECM pin-out diagram from the pre-CL Service Manual -

with my annotations for what is actually on my CL-capable wiring harness/ECU

pre-CL there was a separate ECM pin "just" for the Tach
with the change to CL, the tach output was combined with the "main relay" pin

(and I have not even attempted to understand,
what the original schematic shows was happening, with the main relay)




the full .pdf is too big to make a clear image file to post here;

here is a link to my original .pdf if you want to see all the pins

https://www.docdroid.net/fZJMtXp/f225-ecm.pdf

[rodbolt17]

not enough diagram to tell.
if I think about it I may look at the diagram at the shop today.
just because the wire is green does not mean it is a tach signal.