Oil Pressure gauge wiring

Oil Pressure gauge wiring

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Discussion

Rscocca

Original Poster:

127 posts

123 months

Wednesday 17th December 2014
quotequote all
Quick questions.
Should i have power at the oil pressure sensor?
Why does my gauge stay pinned at 5 bar just turning key on?
I checking wiring as per instructions for gauge.
Power at one post, ground at another post and direct to gauge for sender.
Wire connected to gauge side of sender.
Other wire for sender goes to warning light, this wire has 12v with key on?

engine does have oil pressure, confirmed with mechanical gauge, jumps to 60psi while cranking.


MarkWebb

983 posts

216 months

Wednesday 17th December 2014
quotequote all
Gee I'm guessing that you have one of those new fancy LS motors? smile
I have 2 sensors with one wire each on my rusty old SBC.
One for the gauge with 12v from the gauge connected. It is a variable resistor which changes with pressure so making the gauge move.
The other is for the light which is purely a switch which allows current to flow when pressure is below 15psi and not when above.
The engine makes the neg side of the connection.
4 wires! I am confused confused
Sorry I can't help but i'm sure that somebody who can will give you a sensible answer.

Rscocca

Original Poster:

127 posts

123 months

Wednesday 17th December 2014
quotequote all
Mark,
you are correct, nice new crate ls7.
Problem is not with LS7 harness.
This is the factory supplied oil pressure gauge.
It has power at the sender being supplied via the warning light circuit, then cross feeds to the pressure side of the sender.


UltimaCH

3,155 posts

188 months

Thursday 18th December 2014
quotequote all
If you are using factory supplied stuff, give them a call or send a mail.

macgtech

997 posts

158 months

Thursday 18th December 2014
quotequote all
What is the full range of the gauge in bar? If it is 5 bar, it sounds like you are pulling the 12V across the gauge, maxing it out at 5 bar when the ignition is on. I would guess if you disconnect the sensor from the circuit you still get the 5 bar showing.

Rscocca

Original Poster:

127 posts

123 months

Thursday 18th December 2014
quotequote all
Macgtech,
You are correct.
I ran new wires from battery + and - to gauge and a new run to gauge.
Same result.

Sensor is mounted on the output side of a remote filter housing. An fittings are grounded thru housing I assume( Yes I know its bad to assume.)
I tried a different gauge with similar results.
I have confirmed good pressure with mechanical gauge.

Edited by Rscocca on Thursday 18th December 19:09

macgtech

997 posts

158 months

Thursday 18th December 2014
quotequote all
Rscocca said:
Macgtech,
You are correct.
I ran new wires from battery + and - to gauge and a new run to gauge.
Same result.

Sensor is mounted on the output side of a remote filter housing. An fittings are grounded thru housing I assume( Yes I know its bad to assume.)
I tried a different gauge with similar results.
I have confirmed good pressure with mechanical gauge.

Edited by Rscocca on Thursday 18th December 19:09
How many wires are coming out of the sender? Do you have a link to it online?

GtrMan

134 posts

148 months

Thursday 18th December 2014
quotequote all
could it be you have a floating ground sensor were the other terminal has to be grounded.

Edited by GtrMan on Thursday 18th December 22:39

macgtech

997 posts

158 months

Friday 19th December 2014
quotequote all
A traditional 4 wire sensor has your power +ve and power -ve, along with signal +ve and signal -ve.

The more usual 3 wire approach has a single earth (-ve), a power +ve and a signal +ve.

Two wire devices either change resistance (so you have a -ve and a +ve only and measure the voltage pull) or earth through the body.

Rscocca

Original Poster:

127 posts

123 months

Friday 19th December 2014
quotequote all
An update to everyone, Problem found, I was having a near senior moment.
Basic principals of electricity. It will always be searching for a GROUND.
I had everything going thru an adaptor for the sensor that was not getting a proper ground.

Moved sensor to a different location and what ya know, it works.

Gotta learn to walk away every now and again.

Stubborn mule.