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Oil pressure switch wiring

  • Tireman25
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19 Jan 2018 10:54 #17027 by Tireman25
Oil pressure switch wiring was created by Tireman25
Does a 04 silverado 5.3l oil pressure switch power the fuel pump? The wiring diagram looks like it does but mine only has two weird on it.

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19 Jan 2018 12:58 #17032 by arbez
Replied by arbez on topic Oil pressure switch wiring
I don't see anything in the wiring diagram that indicates that OPS has anything to do with the fuel pump. You should have prime when you first turn the key on & power while cranking.

Can you provide a little more information? 1500 2500 3500? Single or dual tanks. Maybe link us to your wiring diagram & we will try to help.

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19 Jan 2018 13:04 #17033 by Tireman25
Replied by Tireman25 on topic Oil pressure switch wiring
It's just a single tank. I know from watching the videos gm tied the power into the oil switch. It was just in case the relay failed. I got lean codes both banks. My pressure is low so I'm testing the circuit. I pulled the relay and it died. Which if the switch is tied in then it shouldn't have. Probably has nothing to do with low pressure. I'm just curious. I'll find a diagram

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19 Jan 2018 13:10 #17034 by arbez
Replied by arbez on topic Oil pressure switch wiring
Single tank .... 1500???

So the truck is running? Just with low pressure?

If the OPS was involved it would tell the computer if the oil pressure was low & the computer would shut off the pump. It is on or off, It would not cause a low fuel pressure condition.

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19 Jan 2018 19:59 - 19 Jan 2018 20:10 #17060 by graywave
Replied by graywave on topic Oil pressure switch wiring

It's just a single tank. I know from watching the videos gm tied the power into the oil switch. It was just in case the relay failed.

Not true actually. The Switch can not run the fuel pump. The relay is the only device used to supply power to the fuel pump. That is not to say that some vehicles MIGHT, big might, control fuel pump relay based on oil pressure/level signals. Low oil pressure and low oil level usually is not one of those.

I got lean codes both banks. My pressure is low so I'm testing the circuit. I pulled the relay and it died. Which if the switch is tied in then it shouldn't have. Probably has nothing to do with low pressure. I'm just curious. I'll find a diagram

Pulling the relay would have that exact symptom. So no problem there. May I ask how you came to the conclusion you have low fuel pressure?

If you do in fact have low fuel pressure, it could be related to the wiring to the pump, the relay or the supply power to the relay. Obviously the physical pump too. This is where voltage drop measurements would come in very hand. Voltage drop testing is absolute KEY to condoning bad components. Go to ScannerDanner on youtube and search for voltage drop testing. I think he has a video on it. You could search for "fuel pump" as well as he always does voltage drop testing before condoning a pump.

The Oil Pressure Sensor, remember a pressure sensor varies a voltage signal based on a fluid or gas pressure. A switch is ON or OFF like a oil level switch. The Oil pressure sensor is located on the top of the motor, drivers side at the rear. The voltage signal is sent to the pcm and then to the cluster to the oil pressure gauge. On your 2004 Silverado, the oil pressure sensor and the oil level switch have nothing to do with the fuel pump. They only alert the driver with either an OIL Light or a message saying "Check Gauges" or "Low Oil Pressure". Unplugging the oil pressure sensor will send a LOW OIL PRESSURE signal. I forget if high pressure equals low voltage signal or if its the other way around. The Oil Level Switch is located in the side of the oil pan.

I haven't seen a GM yet that will shut down the engine if the oil pressure drops or if there is low oil. Maybe they are out there but they would rather warn the driver and have the driver destroy the engine getting to safety then just having it shut down and potentially causing an accident and loosing a life.

Hope to hear back.

In the diagram below for a 2004 Silverado 5.3. The dark green / white wire to the relay is the PCM FUEL PUMP CONTROL. The Relay is power side switched meaning that dark green white wire will have battery voltage on it when its energized. If you have dual tanks, the second fuel pump relay will be PCM controlled as well on the TAN wire but it will be ground side switched from the PCM but power side switched from the main fuel pump relay on the GRAY wire.

Oil Level Switch has 2 wires
Oil Pressure Sensor has 3 Wires


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Last edit: 19 Jan 2018 20:10 by graywave.
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19 Jan 2018 20:28 #17063 by Tireman25
Replied by Tireman25 on topic Oil pressure switch wiring
I hooked a pressure gauge up to it and it's 55 psi at idle. Then on snap r throttles it drops to 30 psi. I really don't know where I should do a drop voltage test that's easy to access. I hooked up an amp clamp as close to the pump itself that was accessible. It only read 5 amps. With the oil pressure switch controlling the pump. I learned about that on scanner danners videos. In one of them he says if you pull the relay it will continue to run of the power supply from the oil switch. So if you ever do fuel injection cleaning at the rail you have to unplug the fuel pump harness. There are videos on YouTube of other people testing this circuit also.

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19 Jan 2018 21:01 - 19 Jan 2018 21:07 #17067 by graywave
Replied by graywave on topic Oil pressure switch wiring
That video is of a much older GM engine and does not pertain to yours at all. Don't follow that video, it will only confuse you. As you can see in the wiring diagram I supplied to you, there is no oil pressure switch that is involved. That oil pressure switch is a completely different design than what is on your truck. Yours does not have a oil pressure switch, it has a oil pressure sensor, very different.

Compare this 2004 5.3L engine to the engine in that video

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Last edit: 19 Jan 2018 21:07 by graywave.

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