It might help to provide some discussion about hooking up your VOM instrument.
When you put the meter in line, that is, disconnecting the lead from the
harness to a contact, you're measuring the current that device will draw when
powered up. You must set the VOM to current, not volts and especially not
Ohms/Resistance.
Putting the meter across the same circuit, positive test probe to the contact,
while it is connected to the harness, and negative to a good ground, measures
voltage. Set your meter accordingly.
To measure the resistance as Graeme described, disconnect the harness from the
sending unit, connect your negative test probe to a good ground (a clean part
of the engine, I use the lift hook), and the positive probe to the center of
the sending unit, where the harness wire would go.
Set VOM to Resistance, write down the reading in Ohms when the engine is cold,
and do all this again after the engine has warmed up. If your test probes have
clips or you're brave, you can connect while the engine warms up and watch the
resistance change.
Hope helpful.
Paul
Another ~ZoltVolt~ wireless picture msg
-----Original Message-----
From: Graeme Suckling <graemes@internode.on.net>
Sender: datsun-roadsters-bounces@autox.team.netDate: Sun, 13 Nov 2011 16:34:17
To: <datsun-roadsters@autox.team.net>
Subject: Re: [Roadsters] sending units, gauges, and multi meters
Hi Oliver,
the Temperature Sender must be grounded properly so use the MM on
resistance to check for that.
If the sender is grounded OK, connect the MM to the centre post of the
sender and start the engine.
The sender is an NTC resistor, Negative Temperature Coefficient, which
means it will read high resistance when the coolant is cold then the
resistance will drop as the coolant warms up.
Another check is to ground the sender wire in the engine bay and with
the key ON the gauge should max out.
The Oil Pressure Sender is also a variable resistor so check what the
resistance is with the engine off, then start it up and the resistance
should change as the pressure builds up. This is for a gauge. If you
just have an oil light then the sender will disconnect the ground signal
after the pressure builds up thus extinguishing the warning lamp
The Fuel Sender is a really simple variable resistor, a float arm moves
a wiper over a coil of wire to vary the current fed to the gauge.
Disconnect the wiring and remove the sender. Connect the MM to the wire
terminal and the metal frame. You can check it by sliding the float arm
up and down the resistor windings.
If the sender is in the tank, check that it is grounded properly, Black
wire, turn the key ON and you should see a voltage on the sender wire,
the value of which will depend on the fuel level and hence the float level.
As for the gauges, they all need power on one side so use the MM on
voltage and check for 12V on the Oil Gauge, whereas the Fuel and Temp.
gauges are fed a reduced voltage from the stabiliser that you mentioned
when the key is ON.
Hope this helps:)
Regards,
Graeme Suckling
1965 SP310 Datsun Sports
1971 P510 Datsun 1600
1972 PL510 Datsun 1600 LHD
1973 HS30 Datsun 240Z
1984 B120 Datsun 1200 utility
1993 ECR33 Skyline GTS25t
http://tinyurl.com/6n5aza
Adelaide
South Australia.
On 13/11/2011 4:01 PM, oliver wrote:
> hi, all.
>
> I've got the car together and running after many, many years (I received it in
> kit form) and I'm trying to get readings on the gauges.
>
> I think the wiring is right, but of course who knows, right? I'm not sure if
> the sending units work either.
>
> if the gauge sits on a reading and doesn't move when connected, its probably
> broken, right?
>
> if I connect the multi meter between the sending unit and the voltage
> stabilizer, should I get a changing reading as the engine warms up and the
> temperature or oil pressure changes? for the gas gauge I've got to pull the
> sending unit and move it, but I'm confused on the measurement - am I measuring
> volts? resistance? what should I set the resistance to on the meter?
>
> thanks!
> ________________________________________
>
> datsun-roadsters@autox.team.net
>
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