more on F225TXRD Fuel Pump Driver / ECM - Boscoe?

[fairdeal]

so, the other day while "researching" the fuel pump driver circuitry, I kept asking myself
"where is that diagram of the ECM pinout by function, I know I've seen it before"?

Pored over every page in the "Electrical Systems" section of the SM - not there. WTF?

Stumbled over it this morning while looking for something else -

its not in the Electrical section but rather 300 pages away -
in the front, page 15! in the "Fun Facts about this Engine" section



Its a wealth of information; would be helpful in many situations

in the context of the fuel pumps, it explicitly lays out the control circuit schematic,
and the associated ECM pin;
allowing cross-reference of the ECM pin to wire color in the "wiring diagram".




So in hindsight, the answer to the pump driver wiring "mystery" was in the SM all along.

However, I'm now puzzled by something else.

The circuit schematic shown for the HP pump "relay" is classic and obvious.

But the symbology right next to it for the LP pump is very different.

Why the difference?

[boscoe99]

Thanks for the info. Nothing like making it easy for the mechanic eh?

This is the preamble to the diagram. Anyone see a possible error in this statement?

Electronic control system
The ECM controls the ignition timing, the fuel injection timing, the fuel injection volume, and the ISC and it maintains a stoichiometric air-fuel ratio in all operating conditions, including starting and idling. Also, the ECM converts the signals from the input sensors and sends instructions to each part.

[99yam40]

"fuel injection volume" should be on time maybe.

"ECM converts the signals from the input sensors and sends instructions to each part" is very poorly written

[fairdeal]

This is the preamble to the diagram. Anyone see a possible error in this statement?

Electronic control system
The ECM controls the ignition timing, the fuel injection timing, the fuel injection volume, and the ISC and it maintains a stoichiometric air-fuel ratio in all operating conditions, including starting and idling. Also, the ECM converts the signals from the input sensors and sends instructions to each part.

hmm well, as Rodbolt often points out, the ECM arguably has no "control" over the ISC, only able to make a "request"...and I suppose that is perhaps true for some of the other things it is "con*****ing"


and then I believe you, Boscoe, have reported that Yamaha operation is often far from "stoichiometric" - so perhaps that's what you mean?

[fairdeal]

But getting back to my original question -

what do you make of those pump driver schematics?

One point I see, is that it appears that the separate 12V+ supply, to the driver itself, is NOT used for the HP pump relay.

But it appears that it IS used for the LP pump relay.

That is certainly something that could be confirmed with testing.

[99yam40]

to me it looks like the HP pump and relay both get the 12V+ from the same place.

Where is the driver?
Is it not the relay by the pump in schematic?

is there a legend that shows what the dot with a circle around it is?

[boscoe99]

hmm well, as Rodbolt often points out, the ECM arguably has no "control" over the ISC, only able to make a "request"...and I suppose that is perhaps true for some of the other things it is "con*****ing"


and then I believe you, Boscoe, have reported that Yamaha operation is often far from "stoichiometric" - so perhaps that's what you mean?

You got it. Winner winner free chicken dinner.

[boscoe99]

But getting back to my original question -

what do you make of those pump driver schematics?

One point I see, is that it appears that the separate 12V+ supply, to the driver itself, is NOT used for the HP pump relay.

But it appears that it IS used for the LP pump relay.

That is certainly something that could be confirmed with testing.

As the resident test expert you should just do it.

[boscoe99]

to me it looks like the HP pump and relay both get the 12V+ from the same place.

Where is the driver?
Is it not the relay by the pump in schematic?

is there a legend that shows what the dot with a circle around it is?

If there is I have not found it but it surely seems to represent the common 12 volts power supply on the red wire with a yellow tracer.

[fairdeal]

to me it looks like the HP pump and relay both get the 12V+ from the same place.

Where is the driver?
Is it not the relay by the pump in schematic?

is there a legend that shows what the dot with a circle around it is?

there is no legend, but its clear from the full diagram the "the dot with the circle" is 12V+ switched by the main relay

(I would guess all - or most - of the red/yellow wires in the harness)



The driver - this is on the 2005 F225 - is an interesting thing,
a single solid state module mounted on the floor of the cowling base
that incorporates BOTH the LP and HP pump "relays"
(and ALSO has some function with the regulator/rectifier output)

It has 14 wires, in 5 connectors !

One, black, and heavier wire gauge than the others, is apparently the power running the LP and HP pumps

[boscoe99]

What SM number are you looking at?

[fairdeal]

What SM number are you looking at?

LIT-18616-02-76
1st edition, Sept 2003

I have a TXRD built 11/04
the only differences I can recall noticing:
carbon canister & associated venting parts
harness has the CL connector

[rodbolt17]

whats really funny.
you guys cannot wrap your head around voltage and current.

yep BOTH pumps have 12v from the yellow/red to ground anytime the key is on.
not a hard concept to grasp.
\
to make the DEVICE work the DEVICE must have a ground path.
that is what the ECU does.
whether the ECU triggers a ground path for a relay or directly through the ECU is the desiners choice.

FOLKS trons is simply trons.

there is a very specific rule on how trons work.

unless you have to deal with some radar stuff.


voltage is simply how much pressure is avalible, CURRENT is what makes the thang work.

most techs are simply to stupid or untrained to actually use a DVM correctlty.

god help them if I were to give them a simpson 260.
\

why don't most posters simply read the manual for the meter?
it explains most of it.

but at the end of the day , trons is trons.

[fairdeal]

Hi Rodbolt

ok, so its a theoretical question, not a practical one -

but the question is "exactly what is going on inside the solid state F225TXRD driver module,

is it different for the two pumps,

and why"



The symbology for HP pump invokes a classic magnetic relay - surely that's not what's in there, but the concept is recognizable

But what are they trying to convey, with different symbology, for the LP pump ?

and why?

[boscoe99]

Some of rodbolts answers sometimes make no sense at all to me.

Is it me?