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Fred_Allen_Burge
06-30-2005, 11:42 AM
Hey,
I need some clarification on just how the fuel pump relay works on an S14 if anyone knows.

It appears that the ECU gives it a signal from ECU pin 8, that energizes the coil inside the relay which magnetically closes the other two contacts inside the relay and allows electricity to flow from the ignition switch to the fuel pump.

I assume the ECU activates the relay through Pin 8 but can't understand exactly how. Is the ECU sending electricity TO the relay or is it somehow making a ground which allows electricity to come through the relay FROM the ign.switch?

Thanks for any help.
allen

Fred_Allen_Burge
06-30-2005, 12:08 PM
Page EC-7 of the FSM if you want to look. But, I talked to a guy here and he said that the ECU switches the ground at Pin 8 which makes total sense to me. I guess the ign.switch sends juice to the relay and the ECU allows the juice to come through by grounding Pin 8.

allen

RDM_II
06-30-2005, 12:30 PM
You got it.

Black/pink, ground feed from ECU to trigger coil.
White/black, +12V from battery to power fuel pump.
Green, ignition, porvides +12V for opposite side of coil.
Black/yellow, +12V out to drive pump.

orion
06-30-2005, 12:30 PM
That's how the e-fans are controlled on an S14...makes sense they would do the same for the fuel pump.

And FYI...it turns on to prime for 3 seconds, then off if the ECU does not read 180* of crank rotation by the CAS in the distributor.

I assume you're turning it on manually, or using the 6-cyl ECU for your project...but FYI anyway.

- Brian

EDIT: Russ beat me to it, and with a more detailed answer...as expected. http://forums.freshalloy.com/images/graemlins/wink.gif

Fred_Allen_Burge
06-30-2005, 12:56 PM
Thanks gents, both very helpful responses. Does anyone know where in the FSM it actually gives a diagram of the pins of the fuel pump relay and their colors in case I loose track of this post?

P.S.
Yup, trying to figure out what all needs to be wired up to make the 6cyl engine and ECU get power to the right places.

So far I figure I need to get juice from M63 pin 1 in the s14 dash harness and run it to the the VQ's injectors and coils as well as use M63 pin 10 for the VQ's IACV and pin 9 for the VQ's MAF.

The fuel pump I'll turn on by using pin 11 of the VQ's ecu wired into the s14's fuel pump relay.

The starter will already crank the motor wired into the stock KA lower engine harness and I should be able to use the stock lower harness to hook onto the VQ's alternator too.

The VQ's o2 sensors are heated (looks like the KA's aren't)and need power from somewhere, not sure where yet.

The VQ's rear crank pos. sensor needs power from somewhere too.

All other sensors don't need switched power, I guess they get their juice straight off the ECU.

It appears that M63 is the best place to get ignition switched power on the s14.

Anyone see anything wrong w/ my thinking yet?

allen

RDM_II
06-30-2005, 02:09 PM
Pull O2 heater power from the brown wire in M63, I forget which pin but it's the 10A circuit that feeds the O2 and all the EVAP sensors on the S14. FSM will diagram it for you.

Coils and ignitor can go to the black/red main ignition (pin1 ?) like you would use on an SR, you can use the S14's ECCS relay to power the MAF and CAS, just like on an SR also. Rear crank sensor can be tied in with the S14's front crank sensor.

Fred_Allen_Burge
06-30-2005, 04:29 PM
Pull O2 heater power from the brown wire in M63, I forget which pin but it's the 10A circuit that feeds the O2 and all the EVAP sensors on the S14. FSM will diagram it for you.




It looks like the KA's front o2 sensor doesn't get any power but I can use M63 pin 10 (brown, like you said)which feeds power to the KA's rear o2 sensor.



Coils and ignitor can go to the black/red main ignition (pin1 ?) like you would use on an SR



Looks good for the M63 Pin 1 (black/red, like you said) to power the coils and ignitor (if the VQ has an ignitor, don't know much about those yet).



you can use the S14's ECCS relay to power the MAF and CAS, just like on an SR also.



How can I use the s14 ECCS relay, it came out w/ the KA's engine harness I believe?



Rear crank sensor can be tied in with the S14's front crank sensor.



Don't think I can use the KA crank sensor wiring either since it dead ends at E208 (where you unplug the KA engine harness from the lower harness by the fuel filter, and the harness is now gone of course). Now that I look at it, the KA's Crank sensors don't appear to get any switched power anyway, hmmm.

I think I'll just give it power from M63, just use the pin I'm using for the MAF or the IACV and see what happens.


Thanks for the help, btw
allen

RDM_II
06-30-2005, 04:56 PM
It looks like the KA's front o2 sensor doesn't get any power but I can use M63 pin 10 (brown, like you said)which feeds power to the KA's rear o2 sensor.




Forgot you have a 95, they have a 1-wire front sensor.



Looks good for the M63 Pin 1 (black/red, like you said) to power the coils and ignitor (if the VQ has an ignitor, don't know much about those yet).



If it has coils, it has an ignitor, has to.




How can I use the s14 ECCS relay, it came out w/ the KA's engine harness I believe?



There's a red and red/black lead coming from M63 and from the ECU, that's the feeds to the relay. The black/white output drives the CAS and MAF. Check the FSM for the schematic.






Don't think I can use the KA crank sensor wiring either since it dead ends at E208 (where you unplug the KA engine harness from the lower harness by the fuel filter, and the harness is now gone of course). Now that I look at it, the KA's Crank sensors don't appear to get any switched power anyway, hmmm.




Good point, without the lower harness it's a dead lead.

Fred_Allen_Burge
06-30-2005, 08:41 PM
How can I use the s14 ECCS relay, it came out w/ the KA's engine harness I believe?


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There's a red and red/black lead coming from M63 and from the ECU, that's the feeds to the relay. The black/white output drives the CAS and MAF. Check the FSM for the schematic.



Ok, gotcha. So, since the original KA ECCS relay wiring is now gone I'll use M63 pin 9 (red) to feed two of the prongs on the ECCS relay. I'll feed one of the other side's prongs to the VQ ecu (so it can turn the relay on or off) and the last prong to the MAF for it's power. (The CAS (cam pos. sensor) doesn't need switched power on the VQ like the KA does so getting it power isn't a concern).

My next question is - why do I need to run the MAF through a relay anyway? Why can't I just run juice straight to it from M63 Pin 9 (ignition power)? Does the ECU ever turn that relay off when the car is runing??

P.S.
This post is full of priceless info for anyone considering running an alternate engine in their S14. All the KA wires I'm using will be needed for basically any engine you want to swap in, take note!

thanks,
allen