Jump to content
SAU Community

Power Fc - How It Saves It's State

rtune

By rtune,
in Engines & Forced Induction

 Share

Recommended Posts

rtune Experienced

rtune

Posted
Posted

From the power fc FAQ, this circuit diagram is the closest I have come to an answer

to my query:

http://paulr33.skylinesaustralia.com/docs/...eccs-wiring.jpg

So I understand that IGN on powers up the pfc ecu (or the stock ecu) and, START

makes the ECU light up the ECCS relay and the Coil relay: the ECCS relay

powers up the CAS sensor and the AFM (engine sensors) and the coil relay lights

up the coils.

ECU senses cam position etc etc & fires & car starts.

What I don't understand is what happens to trigger the power-fc to save state

and the sequence during shutdown..

I've seen several posts about in other forums particularly where either

the ECCS relay is broken or the wiring loom is wrong or the engine has been

swapped (wiring loom wrong) and the save problem is in the power-fc faq.

So.. ignition goes off and .. what? the ECU, still powering itself through ECCS,

writes all the changes to non-volatile memory, then does _it_ turn off the ECCS

relay itself by pulling pin 16 to ground? (which withdraws power to the engine

sensors and other pins on the ECU)? is the ECCS relay just a regular relay like

any other or is it more complicated inside?

If it works as I describe does simply supplying non switched 12v to pin 49/59/109

with an inline fuse, does that allow the power-fc to save its state (although since

this would leave power to the ecu always, perhaps it be a drag on the battery).

The reason for all this is I have a car alarm that is so knitted into the wiring that

it is able to pull ALL power from the ecu connector on ignition off.. I'm faced with

a choice - pull the dash and pull out the entire alarm, or solve the immediate

problem to get power-fc to save state..

Link to comment
https://www.sau.com.au/forums/topic/246090-power-fc-how-it-saves-its-state/
Share on other sites
GreeceS13 Rising Star

GreeceS13

Posted
Posted

The pfc needs 1sec more 12V at pin49,59 when you cut the voltage at pin 45 (so when you cut ignition).

12V Ign at Pin 45

12V Permanent at pin 58

Pin 16 to the relay and suply the relay with battery voltage with a new wire from the battery with a fuse so you will be sure thaw this voltage you will not cut from alarm.

rtune Experienced

rtune

Posted
  • Author
Posted
suply the relay with battery voltage with a new wire from the battery with a fuse so you will be sure thaw this voltage you will not cut from alarm.

so with the ecu unplugged you should be able to see 12v on ecu harness pin

16 and 58.. and if you ground 16 (which turns on the ECCS relay, listen for a click),

you should then see 12v on 49,59 and 109 as well ?

Is that a good test?

GreeceS13 Rising Star

GreeceS13

Posted
Posted

Oh you will melt something or you melted!!!

Pin 45 12V Ign

Pin 58 12V Permanent

When your ignition is on (red lamps at dash), so when the ecu have 12V at pin 45.... the ecu gives a ground at PIN16!!!

This ground opens the ecu relay!! So the ecu relay sends 12V to the 49,59!

If you gave or if you will give 12V at pin16 you will melt this pin and you will not anymore ground exit. (if you did it, I will tell you what solution I found)!

Ecu relay..

1 and 3 needs one ground (ground from pin 16) and one 12V permanent.

3 and 5 at 3 12V permanent and at 5 a wire that goes at pin49,59.

To understand which pin is the 3,5,1,2 see under the relay... it has some small numbers near each pin. The scheme at the face of the relay (that writes NISSAN) isn't with the right way printed.

Just read what I said you to connect at the relay and look at the metal pins to find some very small letters nears the pins and you will see the numbers.

rtune Experienced

rtune

Posted
  • Author
Posted (edited)
Oh you will melt something or you melted!!!

Pin 45 12V Ign

Pin 58 12V Permanent

When your ignition is on (red lamps at dash), so when the ecu have 12V at pin 45.... the ecu gives a ground at PIN16!!!

This ground opens the ecu relay!! So the ecu relay sends 12V to the 49,59!

If you gave or if you will give 12V at pin16 you will melt this pin and you will not anymore ground exit. (if you did it, I will tell you what solution I found)!

Ecu relay..

1 and 3 needs one ground (ground from pin 16) and one 12V permanent.

3 and 5 at 3 12V permanent and at 5 a wire that goes at pin49,59.

To understand which pin is the 3,5,1,2 see under the relay... it has some small numbers near each pin. The scheme at the face of the relay (that writes NISSAN) isn't with the right way printed.

Just read what I said you to connect at the relay and look at the metal pins to find some very small letters nears the pins and you will see the numbers.

thanks, no I didn't do anything! just hypothetical.

the only time I almost melted something was undoing the battery live terminal

with a spanner and despite being careful in the limited space it touched a bit of chassis

and the zaaap the spanner got warm instantly, luckily I yanked it before it stuck!

ok..

without an ecu connected, just looking at the connector, I was trying to imagine a way to test if the loom

is operating properly with key on, then key turning off. Just test with multi-meter .. I think from your explanation

I can see what is necessary..

with ecu connected it is hard to know what each pin (each wire) has ..

Edited by r34nur
predator Grand Master

predator

Posted
Posted

You should be able to shove a probe in the end of each ECU pin (from behind, you can still access the other end of the pin) and earth the other probe of the multimeter to check for 12v across each pin as you turn on, or turn off the car, and ensure everything is operating as expected.

(edit: what he just said ;))

  • 7 months later...
  • 2 years later...
benl1981 Grand Master

benl1981

Posted
Posted

I know this is an old thread but can you actually hear this slight delay (on shutdown) in the ECCS relay enegizing - can someone confirm this on an R33 rb25det? I.e. so you should hear the engine shut down when you turn the key - then about a 1 sec pause before you hear the relay kick in?

Is the ECU programmed to delay 1second before triggering that relay, is that how it works?

Why does the stock computer require that delay? is it for writing fault codes? As I understand the PFC requires it for tune writing.

Thanks

89CAL Grand Master

89CAL

Posted
Posted

Yeah you should be able to hear the relay click off after a short delay.

I'm not 100% sure on the stock ECU, but it may just be to save Crank position and general state of the car when it turns off to help with startup

But I dont know for sure, havent had a stock ECU for a while now

benl1981 Grand Master

benl1981

Posted
Posted

thanks for that.

Back up on some of the other threads it talks of a permanent 12v to pin 58.

My r33 has 12v to that when ign is on but as soon as you switch the ign off this voltage drops but fairly slowly. Drops to 4v then drops about .1v every few seconds. Maybe the alarm is connected in with this 12v feed?

I would think this is the reason my ecu shuts down earlier as it would need the constant 12v to allow the eccs to shutdown the computer.

Thinking of running a permanent 12v line from maybe the clock over to the ecu so that pin 58 does in fact have a constant 12v. Unless there would be a closer constant 12v feed than to the clock.

I don't want to wreck the harness though. Would I be best tracing pin 58 wire back slightly and splice this wire I run in at that point?

Does the above make sense to anyone. It is strange my pin 58 doesn't keep 12v ..

  • 3 years later...
jan25 Contributor

jan25

Posted
Posted

once confirmed, please advise

will add to PFC FAQ

This is a very old tread but we have the solution for years and fixed many PFC's with that issue.

If anyone has got that sort of problem please contact us on http://fc-hako.com/pfc/contact/

Will be fixed and tested in one day. If the issue is with engine harness we will advice you how

to test it before shipping the PFC to us.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Randhj
      R34 4 door indicator and horn issue

      By Randhj · Posted

      Thanks, I removed the fuse and the relay from the car and made my own circuit with them to test them with a test bulb.  I will look for the wiring diagram and go from there.
    • Milkmun
      The FD RX7 is the best looking 90's JDM car

      By Milkmun · Posted

      Jdm DC2R is also nice for a FF car compared to the regular hatches of the time.
    • PranK
      The FD RX7 is the best looking 90's JDM car

      By PranK · Posted

      Gotta admit, I love the 20b Cosmo.
    • joshuaho96
      Nismo Super Coppermix Twin and R33 GTR transmission replacement

      By joshuaho96 · Posted

      Now that the break-in period for both clutch and transmission is nearly over I'd like to give some tips before I forget about everything that happened, also for anyone searching up how to do this job in the future: You will need at least 6 ton jack stands at full extension. I would go as far as to say maybe consider 12 ton jack stands because the height of the transmission + the Harbor Freight hydraulic platform-style transmission jack was enough that it was an absolute PITA getting the transmission out from under the car and back in. The top edge of the bellhousing wants to contact the subframe and oil pan and if you're doing this on the floor forget about trying to lift this transmission off the ground and onto a transmission jack from under the car. Also do not try to use a scissor jack transmission lift. You have to rotate the damn thing in-place on the transmission jack which is hard enough with an adjustable platform and a transmission cradle that will mostly keep the transmission from rolling off the jack but on a scissor lift with a tiny non-adjustable platform? Forget it. Use penetrating oil on the driveshaft bolts. I highly recommend getting a thin 6 point combination (box end + open end) wrench for both the rear driveshaft and front driveshaft and a wrench extension. These bolts are on tight with very little space to work with and those two things together made a massive difference. Even a high torque impact wrench is just the wrong tool for the job here and didn't do what I needed it to do. If your starter bolts aren't seized in place for whatever reason you can in fact snake in a 3/8 inch ratchet + 6 point standard chrome socket up in there and "just" remove the bolts for the starter. Or at least I could. It is entirely by feel, you can barely fit it in, you can barely turn the stupid ratchet, but it is possible. Pull the front pipe/downpipe before you attempt to remove the transmission. In theory you don't have to, in practice just do it.  When pulling the transmission on the way out you don't have to undo all the bolts holding the rear driveshaft to the chassis like the center support bearing and the rear tunnel reinforcement bar but putting the transmission back in I highly recommend doing this because it will let you raise the transmission without constantly dealing with the driveshaft interfering in one way or another. I undid the bottom of the engine mount but I honestly don't know that it helped anything. If you do this make sure you put a towel on the back of the valve cover to keep the engine from smashing all the pipes on the firewall. Once the transmission has been pulled back far enough to clear the dowels you need to twist it in place clockwise if you're sitting behind the transmission. This will rotate the starter down towards the ground. The starter bump seems like it might clear if you twist the transmission the other way but it definitely won't. I have scraped the shit out of my transmission tunnel trying so learn from my mistake. You will need a center punch and an appropriate size drill bit and screw to pull the rear main seal. Then use vice grips and preferably a slide hammer attachment for those vice grips to yank the seal out. Do not let the drill or screw contact any part of the crank and clean the engine carefully after removing the seal to avoid getting metal fragments into the engine. I used a Slide Hammer and Bearing Puller Set, 5 Piece from Harbor Freight to pull the old pilot bearing. The "wet paper towel" trick sucked and just got dirty clutch water everywhere. Buy the tool or borrow it from a friend and save yourself the pain. It comes right out. Mine was very worn compared to the new one and it was starting to show cracks. Soak it in engine oil for a day in case yours has lost all of the oil to the plastic bag it comes in. You may be tempted to get the Nismo aftermarket pilot bearing but local mechanics have told me that they fail prematurely and if they do fail they do far more damage than a failed OEM pilot bushing. I mentioned this before but the Super Coppermix Twin clutch friction disks are in fact directional. The subtle coning of the fingers in both cases should be facing towards the center of the hub. So the coning on the rearmost disk closest to the pressure plate should go towards the engine, and the one closest to the flywheel should be flipped the other way. Otherwise when you torque down the pressure plate it will be warped and if you attempt to drive it like this it will make a very nasty grinding noise. Also, there is in fact an orientation to the washers for the pressure plate if you don't want to damage the anodizing. Rounded side of the washer faces the pressure plate. The flat side faces the bolt head. Pulling the transmission from the transfer case you need to be extremely careful with the shift cover plate. This part is discontinued. Try your best to avoid damaging the mating surfaces or breaking the pry points. I used a dead blow rubber hammer after removing the bolts to smack it sideways to slide it off the RTV the previous mechanic applied. I recommend using gasket dressing on the OEM paper gasket to try and keep the ATF from leaking out of that surface which seems to be a perpetual problem. Undoing the shifter rod end is an absolute PITA. Get a set of roll pin punches. Those are mandatory for this. Also I strongly, strongly recommend getting a palm nailer that will fit your roll pin punch. Also, put a clean (emphasis on clean) towel wrapped around the back end of the roll pin to keep it from shooting into the transfer case so you can spend a good hour or two with a magnet on a stick getting it out. Do not damage the shifter rod end either because those are discontinued as well. Do not use aftermarket flywheel bolts. Or if you do, make sure they are exactly the same dimensions as OEM before you go to install them. I have seen people mention that they got the wrong bolts and it meant having to do the job again. High torque impact wrench makes removal easy. I used some combination of a pry bar and flathead screwdriver to keep the flywheel from turning but consider just buying a proper flywheel lock instead. Just buy the OS Giken clutch alignment tool from RHDJapan. I hated the plastic alignment tool and you will never be confident this thing will work as intended. Don't forget to install the Nismo provided clutch fork boot. Otherwise it will make unearthly noises when you press the clutch pedal as it says on the little installation sheet in Japanese. Also, on both initial disassembly and assembly you must follow torque sequence for the pressure plate bolts. For some reason the Nismo directions tell you to put in the smaller 3 bolts last. I would not do this. Fully insert and thread those bolts to the end first, then tighten the other larger pressure plate bolts according to torque sequence. Then at the end you can also torque these 3 smaller bolts. Doing it the other way can cause these bolts to bind and the whole thing won't fit as it should. Hope this helps someone out there.
    • PLYNX
      The FD RX7 is the best looking 90's JDM car

      By PLYNX · Posted

      Of the 90s ! !
×
×
  • Create New...