Dan's PNP RB25DET R33 Skyline ECU PCB

[Dan]

OK so I think I have the schematics sorted bar the injector and ignition output configuration (need to talk to mr cooke about this) and if my assumptions about using pins for different stuff is correct (need to talk to mr cooke about this also).

Does anyone know what the Nissan Fuel Pump Control Module (FPCM) does? It looks like a PWM controller? It basically switches the fuel pumps -ve to ground and is controlled by the OEM ECU.

Link to some info --> http://www.skylinesaustralia.com/forums ... -resistor/

EDIT: Repo is updated!

[Dan]

I am starting to think that the Nissan FPCM is just a switch? when ON, it bypasses a resistor that Nissan have fitted between the fuel pump ground and chassis. From what I have read, it is purely to reduce pump noise at idle and then apply full voltage to the pump, by bypassing the resistor, when off-idle?

Anyone else have any words of wisdom on this beast?

EDIT: spelling.... lol

[Dan]

Just found this

[Corbon]

From what I could tell the FPCM works just like you say, as a switch with no PWM.

On ECU pin 104 I see ~10V while idling and pulls down to circa 0V as soon as you give it a rev. The change in pump noise when it switches over is quite noticeable.

[Hell Fire]

I will confirm that it's not PWM, if it were, people wouldn't be having so many problems with replacement pumps not putting up with the reduced voltage (and thus, reduced torque).

[Dan]

Excellent. Thanks for the good data gents, i will design that circuit accordingly

EDIT: Fred, i will put hardware in place for it, if it cant be supported initially, then people can bridge it low on the pcb

[Dan]

The DTC detection logic (in my linked image above) tells the story that the OEM ECU looks for a voltage during engine cranking on the control wire. (ie. the pull-up must be inside the FPCM).

Therefore, a simple low side drive should do the trick with this as it should just float to approx ~10V when the LSD isn't on.

[Dan]

I am having difficulty locating a suitable counter ic with an spi interface for the VSS.

I have found this one --> http://www.lsicsi.com/pdfs/Data_Sheets/LS7366R.pdf

It is way overkill though.

There is a dual 16-bit counter ic (74 series logic) that one can use a shift register with to make a crude spi interface. Surely there is a better option out there though.

If anyone knows of anything please let me know.

[Dan]

Or could we get tricky and use something like this

Link --> http://datasheets.maximintegrated.com/en/ds/DS1682.pdf

[Fred]

1/4 second resolution.