[Diy_efi] Sending unit confusion

[Perry Harrington]

The sending unit may be connected like a temp sensor.  The sender has
a bias resistor between ground and the input.  12v is supplied to the
input of the sender and the output pulls the voltage up or down through
the bias resistor.  If the sending unit isn't grounded, then with 2
wires it has to be biased externally.

--Perry

On Thu, Feb 20, 2003 at 02:20:01PM -0500, Toyota Supra wrote:
> i did, i will try again, just to double check, and let you know
> 
> 
> 
> 
> 
> 
> >From: Robert W Hughes <rwhughe at oplink.net>
> >Reply-To: List for general do-it-yourself EFI talk <diy_efi at diy-efi.org>
> >To: diy_efi at diy-efi.org
> >Subject: Re:[Diy_efi] Sending unit confusion
> >Date: Thu, 20 Feb 2003 09:58:08 -0600
> >
> >TRy connecting the case/mounting flange to ground.
> >
> > > in my never ending quest to conquer this circuit, i have encountered
> > > something very strange. when i removed the fuel level sending unit to 
> >try
> > > and test my circuit, i found that i am not able to simulate its 
> >electrical
> > > function.
> > > the sending unit has 2 wires, a yellow and a brown w/ black tracer. when 
> >the
> > > sending unit is not plugged into the body harness, the yellow wire has
> > > +12vDC (or whatever battery voltage may be) on the body harness side of 
> >the
> > > connector, and the brown w/ black tracer has approximately 15k of 
> >resistance
> > > to ground, or 35mV of positive voltage.
> > >
> > > when the connectors are plugged in, the yellow wire will have anywhere 
> >from
> > > 0 to 3.5vDC, dependent on the position of the "float". the variable 
> >resistor
> > > will have resistance ranging from 0k to 55k.
> > >
> > > now, my problem is, i can't simulate the variable voltage outside of the
> > > vehicle, to test my circuit. if i put 12vDC into the yellow wire, the 
> >brown
> > > w/ black tracer will also have 12vDC, so what could that wire possibly 
> >be
> > > doing, or connected to, that would make the circuit and unit work 
> >properly?
> > >
> >
> >--
> >Robert W. Hughes (Bob)
> >BackYard Engineering
> >29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W
> >Houston, Texas "The city with too much Oxygen"
> >rwhughe at oplink.net
> >
> >_______________________________________________
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> >Diy_efi at diy-efi.org
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> 
> 
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-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

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