Oil pressure safety switch wiring help
06-23-2018, 09:51 PM
#1
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Oil pressure safety switch wiring help Today I tried my hand at installing a fuel pump relay and oil pressure safety switch, but didn't quite get the result I'm looking for. The fuel pump isn't supposed to run until the oil pressure sensor hits 5 psi, but right now the pump turns the second I hook the ground cable up on the battery, so obviously I've got my constant wrong, but not sure how to make it all work together. This is how I have it right now:
From the relay:
30 - to battery +
85 - to ground
87 - to fuel pump
86 - to "C" on oil pressure switch
From the oil pressure switch:
NC - to starter solenoid
NO - to ignition wire
Any ideas would be great. Thanks.
From the relay:
30 - to battery +
85 - to ground
87 - to fuel pump
86 - to "C" on oil pressure switch
From the oil pressure switch:
NC - to starter solenoid
NO - to ignition wire
Any ideas would be great. Thanks.
06-24-2018, 01:10 AM
#2
TECH Addict
NC and NO may ground ground through the pressure switch not to each other,, they come in single pole single throw or double pole single throw. Use the oil pressure switch to control the ground for the relay not the actual direct power to the pump...
06-24-2018, 05:58 PM
#3
Restricted User
Its not, pin 86 on a typical relay is power for the relay. So he's just powering up the relay and not the fuel pump.
However, I would also agree to using the oil pressure switch for ground and not relay power.
Your relay wiring seems to be fine, so I would guess that the your oil pressure switch wiring is incorrect. You have the NC to the starter solenoid.
NC is normally closed, or the circuit that is connected at all times.
This means its passing power from the starter solenoid through the pressure switch at all times.
However, I would also agree to using the oil pressure switch for ground and not relay power.
Your relay wiring seems to be fine, so I would guess that the your oil pressure switch wiring is incorrect. You have the NC to the starter solenoid.
NC is normally closed, or the circuit that is connected at all times.
This means its passing power from the starter solenoid through the pressure switch at all times.
06-25-2018, 09:43 PM
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Ok so I did some resistance testing, results were as follows:
NC to NO = 1
C to NC = 000
C to NO = 1
Switch housing to frame = 001
I also did some other testing:
With ignition wire (86)(yellow) disconnected from C on the oil switch, there is no power to the purple (87) or yellow (86) wires at the relay. Not even when cranking. Nor is the fuel pump kicking on.
When I attach 86 to C the pump turns on, and 87 and 86 get power at the relay.
When 86 is disconnected from the oil switch NC and C have power when the key is off.
When the key is on, all three terminals on the switch have power, C, NC, and NO.
All this said, it didn't lead me to any conclusions, but I'm no electrician either. Does this lead anyone to a conclusions?
NC to NO = 1
C to NC = 000
C to NO = 1
Switch housing to frame = 001
I also did some other testing:
With ignition wire (86)(yellow) disconnected from C on the oil switch, there is no power to the purple (87) or yellow (86) wires at the relay. Not even when cranking. Nor is the fuel pump kicking on.
When I attach 86 to C the pump turns on, and 87 and 86 get power at the relay.
When 86 is disconnected from the oil switch NC and C have power when the key is off.
When the key is on, all three terminals on the switch have power, C, NC, and NO.
All this said, it didn't lead me to any conclusions, but I'm no electrician either. Does this lead anyone to a conclusions?
07-12-2018, 09:38 PM
#5
Oil press fuel pump relay...
pin...
C- to ruel pump . Gets spliced with pin B from Fuel pump relay (fuel pump signal [power])
D- fused 12v
A- pressure signal to guage
Fuel pressure relay....
pin...
D- 12v pos
C- ground
B- spliced together with pin C from oil press relay. Gets wired to fuel pump. (Fuel pump signal (power).
A- fuel pump relay signal from pcm
these are based on factory gm diagrams for 82-92 s series trucks... obviously you can adapt to use with newer lsx pcm and engines...
pin...
C- to ruel pump . Gets spliced with pin B from Fuel pump relay (fuel pump signal [power])
D- fused 12v
A- pressure signal to guage
Fuel pressure relay....
pin...
D- 12v pos
C- ground
B- spliced together with pin C from oil press relay. Gets wired to fuel pump. (Fuel pump signal (power).
A- fuel pump relay signal from pcm
these are based on factory gm diagrams for 82-92 s series trucks... obviously you can adapt to use with newer lsx pcm and engines...
