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[Music]
hi in this video i will demonstrate how
to test your oil pressure switch
you can test the oil pressure switch
while it's on the car or when it's
removed from the car
many people think the oil pressure
switch is there to tell you how much
oil you have that is incorrect you can
have a minimum amount of oil and still
have sufficient oil pressure in your
engine
the oil pressure switch is there to tell
you when the oil pressure
is low if you have an oil leak you will
lose pressure and therefore the oil
pressure switch should notify your ecu
of that problem you can have an engine
that is full to capacity with oil and
still have
low oil pressure so it's still important
to check the level of your oil
as well just having a look at the
principle of operation we get a normally
open
and a normally closed oil pressure
switch for example this is the switch
body
and the switch is connected to your ecu
and if you look at this one it says
normally
open that means that when the car is off
the point from the terminal there to the
body of the oil pressure switch
is an open circuit when the oil pressure
builds up to the correct point for your
engine
the switch actually goes closed circuit
the ecu monitors the closed circuit and
if the circuit
opens it knows there's a loss of oil
pressure
on the normally closed side the switch
is closed
until there is enough pressure when you
start your car
and the pressure builds up in the engine
it'll actually open
the switch over here the ecu monitors
the switch and if the switch closes
again the ecu knows that there is a loss
of oil pressure
right i have a multimeter and here are
the leads if i have a short circuit
for example i'm measuring across the
screwdriver
this is a dead short and as you can see
it says zero here
or very low ohms you can see they're 1.3
ohms
but you can also hear the buzzer telling
me that it is a
dead short now i've connected the one
lead to that terminal now you can see
there is only one terminal there because
the other terminal is actually the body
if your oil pressure switch looks like
this you will measure between that lead
and the body over there
if yours looks like this you'll measure
between there and there
if yours looks like this you'll measure
between there and there if yours looks
like this you will measure between there
and there if yours looks like this with
a hexagonal head you'll measure between
there
and there and there you can see it is a
dead short telling me that this
is in the closed position now over here
i have compressed air
and i'm going to use the compressed air
to mimic oil
pressure if you do not have compressed
air just do the measurement while it's
on your vehicle
now if i have a look at this oil
pressure switch it actually says on the
body 0.2 to 0.5 bar
it is different for different vehicles
some cars 0.25 all the way up to about
0.75 bars inside the switch
is a diaphragm that is going to move and
open the contacts
as the pressure builds up right now the
contacts are a dead short
you can hear it's a dead short you can
see on my meter
and now i'm going to blow it with the
compressed air
you can see that when i blow the air
there it goes open circuit on the meter
and if i show you the ohms you can see
at the moment it's 2.2
and when i blow into the hole there
you could see on the meter it said
offline meaning that it was an open
circuit
so this oil pressure switch is
functioning correctly
if you were going to test this on your
vehicle so what you'll do is you'll
measure between the terminals
if it's a normally closed switch it'll
be a short circuit when you start your
vehicle and the oil pressure builds up
it should become an
open circuit if your oil pressure switch
is a normally
open oil pressure switch then when you
measure it while the car is off it will
be an
open circuit when the oil pressure
builds up it will become a
closed circuit please note that when i
do blow into the hole here i do not
force it on like that the pressure will
be too high remember this opens at a
fairly low pressure below one bar so be
careful not to have your compressor too
high you do not want to damage the
diaphragm
inside you these tests were conducted at
about one bar
now in some oil pressure switches you
can actually feel the contact moving
inside
for example as i depress the trigger
here
i can actually feel through the body
here the contacts opening and closing
it's almost like a relay
i don't know if you notice i'm getting
some oil residue on my fingers so what
has happened here is
this particular one has leaked the oil
pressure switch is leaking
and i'll quickly show you how to test
that as well you can put a bit of water
here right so you can see i put some
water there and when i blow it you will
see either air bubbles or that level
rising
right so there is the compressed air and
as i press the trigger
look at the water
so you can see in this case the oil
pressure switch electrically works
but has lost its ability to insulate
from the oil
if you do not have an air compressor you
can use that blower
and as i use my blower look what happens
to the water
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so you could see air bubbles and the
water level rises
now on some oil pressure switches it
doesn't leak there but it actually leaks
on the seam
over here so in order to test that what
i do is i
immerse the oil pressure switch in a
glass right there you can see
the leak in the oil pressure switch in
this case it is only leaking over there
which is understandable because this is
a single construction some oil pressure
switches you'll find that it's not like
that and it leaks outside over there
right thanks for watching and cheers
