No power at the oil pressure sending unit wire?

[Mike Phillips]

Shouldn't there be power in the wire lead that attaches to the oil pressure sending unit?

 

Just checked and there's no power in the wire. Pulled the sending unit off and turned the motor over to make sure the oil pump is pumping oils and that's a messy "yes".

 

Plan on installing a mechanical gauge but would like to find out what I need to do to get the idiot light to work until then.

 

Suggestions as to where to look for a electrical problem?

 

Also, so far no headlights. Park lights come on but no headlights. Haven't checked the brake lights yet, will do so in a few minutes when I can back the truck up to the garage door.

 

:)

[Phlebmaster]

All of your "idiot" lights should come on when the key is in the run position before you start it. Check that first..then see if the oil light goes out after you start the motor.

 

I think that is how it works..:cool:

[Mike Phillips]

Here's an update.

 

When key is placed in the run position before I start the engine, the oil pressure idiot light comes on, but nothing else on the gauge.

 

It's dark out and I just tested the end of the wire with my electrical tester and with the engine running the tester glows dimly. So it's getting power but it's very not much.

 

Tested all the fuses at the fuse box with engine running doing a simple test of just touching the probe to both sides of each fuse holder and each touch-point appears to have full power.

 

Wiring is one of my weak points.

 

Tested some other electrical components and will start threads with pictures and information for those components.

 

:)

[yello620]

You need to get a multimeter and test how much power you are getting, a dim lit test light is a sign that something is wrong..

 

Have you found the wiring diagrams at olddat.com? Study them, I have printed them out before and taken them to the local copier store and had them enlarge. This makes following the wires much easier, you can even color code them if you get them large enough.

 

I am guessing that you might have a voltage problem from a dirty connection somewhere..Clean everything. A multimeter will help determine where you are losing power.

[datzenmike]

When you turn the key to on power is applied to the oil pressure RED warning bulb, the other side is grounded through the pressure sender in the block. It should light with no pressure and go out when there is over 6-9 lbs pressure. The light will go out during start, but may come back on briefly when the motor starts and then go out as the pressure rises. Sounds like it's working.

 

When the key is turned to ON (not started)

The charge light for the alternator should light and the gas gauge and temp gauges should read... assuming you have gas in the tank and the motor is warm. The brake light should also light if the E brake is pulled out (on).

Edited October 31, 2008 by datzenmike

[freaky510]

isnt that a ground and the power is on the light side of it all when the pressure is low it makes a ground then the light lights up ?????

I could be very wrong i am the village idiot

[OL YELLER]

[QUO

I could be very wrong i am the village idiot

 

 

NOT IN MY VILLAGE................................THAT IS MY JOB!!!

[datsunaholic]

isnt that a ground and the power is on the light side of it all when the pressure is low it makes a ground then the light lights up ?????

I could be very wrong i am the village idiot

 

That's exactly how it works.

 

So, you won't have a full 12V at the sender lead because it's fed through the dash light. With a test light, it now has 2 light bulbs in SERIES which means each get 6V (more or less, splitting 12V through 2 bulbs).

 

Mike (Phillips), I'm trying to figure out why you think you have a problem. Do you have a light or a gauge? Each requires a different sender. The sender for a light is just a pressure switch, for a gauge the sender is a pressure-actuated variable resistor. In BOTH cases they are simply a return to ground, meaning the light (or gauge) gets full 12V on the other end.

 

If the oil pressure warning light comes on when you have the key on, then the circuit is working. Unless the light comes on when the wire isn't hooked up... then there's a short (but the light would be lit even with the engine running).

 

Also, it would be very helpful if you told us what kind of car this is. No where do you have a Datsun listed in your profile, and my Psychic cap got lost at the dry cleaners. Some Datsuns came from the factory with Oil gauges but most just had the idiot light.

[freaky510]

:D:D:):rolleyes::lol::eek::lol::eek::lol::eek:

 

wow i knew sometin