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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Circuit opening relay - question just to verify
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Tue, 04 November 2003 12:35
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Just to make sure i haven't got this TOTALLY wrong....
I am wiring up a 4age smallport from scratch (ie i had one fucked up loom to deal with). I have sorted just aboot everything, and have got to the 12 pin plug (body plug).
Already i have sorted out W, BATT, B1 and B+... but remaining is FC (circuit opening relay). From the diagrams i have (in japanese) it looks like its a negative output from the ECU to trigger a relay to give power to the fuel pump.
Am i correct in thinking that? Or just way off?
Thanks for any help.
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Location:
Perth
Registered:
September 2002
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Re: Circuit opening relay - question just to verify
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Tue, 04 November 2003 14:20
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from what i know, fuel pumps are wired up two ways
either one side is earthed, and the other floats betwween 0 and 12v (12v at WOT, 1v at idle)
or
one side is constant, and the other floats between 12 and 0 (0v being WOT, 11v at idle)
having said that, i dont see why you cant wire up a pump backwards and give it -12v constant, and -12 to 0 trigger (0v being WOT)
but hey, that could just be speculation
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Location:
Perth
Registered:
September 2002
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Re: Circuit opening relay - question just to verify
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Tue, 04 November 2003 15:04
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actually scrap that last bit
you cant get -12v from a car battery
it has to be one of the first 2 possibilities
have a good look at the diagram again
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Location:
1st street on the right
Registered:
November 2002
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Re: Circuit opening relay - question just to verify
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Tue, 04 November 2003 18:49
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I don't know if it's the same but my crown (5mge) the fuel pump circuit opening relay is switched by two circuits. It is switched with ignition and also switched by the air flow meter (don't know if you have) when the flap is moved. This is a constant voltage, just on/off. It's done as a safety thing if the car stalls (accident) the pump also stops. One of the wires from the AFM will complete a circuit to earth (AFM body, make sure it's not a bad earth  ).
The FC should be ign controlled and have full power at all times through startup to switch the 1st stage of the relay. As you crank the engine the AFM opens and switched the second stage and pump runs. I fed this to another std relay at the pumps. (cuct open is not the pump relay as such)
Justin
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Location:
PNG
Registered:
June 2002
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Re: Circuit opening relay - question just to verify
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Tue, 04 November 2003 21:46
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Gidday
Justin is correct. Have a look at the iggte wiring diagram in the Gallery. It will show the wiring of the circuit opening relay. It is the same for all toyotas with AFM. Basically it there to ensure that if the engine is not running neither is the fuel pump - so if you have a prang the fuel pump is not continuing to pump fuel. All efi cars have some similar form of protection - eg hondas use oil pressure.
Craig
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Location:
Newcastle, NSW, Australia
Registered:
May 2002
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Re: Circuit opening relay - question just to verify
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Tue, 04 November 2003 22:11
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original Question:
"From the diagrams i have (in japanese) it looks like its a negative output from the ECU to trigger a relay to give power to the fuel pump."
Yes, that is correct. The ECU will ground the FC wire and complete the circuit. This is applicable for MAP sensed engines only, not AFM.
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: Circuit opening relay - question just to verify
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Wed, 05 November 2003 10:51
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Thanks a zillion Grant! I checked over the diagrams again today and asked "The Man" a couple of questions, and now i even understand how the actualy Circ openning RELAY itself works (ie priming the pump whilst starting).
Im just going to use a regular SPST relay for now (have heaps spare), and if i have problems starting ill then use the proper Circ opening relay.
P.S. When i said | Quote: |
I am wiring up a 4age smallport
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i would have thought most would know that it's MAP sensor... I don't care for AFM's.
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Location:
1st street on the right
Registered:
November 2002
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Re: Circuit opening relay - question just to verify
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Wed, 05 November 2003 11:33
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Just go to the wreckers and grab one (or two or three....)
I might have a spare if you want one
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: Circuit opening relay - question just to verify
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Wed, 05 November 2003 12:45
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going to the wreckers = time required in the normal 9-5 realm... something which i do NOT have. Hence im using what i have handy at home.
If its a problem THEN i pinch one!
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Location:
Gold Coast
Registered:
January 2003
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Re: Circuit opening relay - question just to verify
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Wed, 05 November 2003 20:39
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you should also have a wire from your start curcuit to trigure the relay on crank
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: Circuit opening relay - question just to verify
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Thu, 06 November 2003 10:40
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thats only to prime the pumps whilst starting - i've worked around it now and have the relay coil and switch feed from permanent 12V, and the other side of the coil to the FC output of the ECU.
It'll work. Mostly.
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