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How does oil pressure sensor work?

How does oil pressure sensor...

How does oil pressure sensor circuit work? The sensor has a 5 volt power supply, signal wire back to the module and another wire acting as a ground, but also connected with the engine temp sender.

With the connector on the oil PSI switch disconnected from the sensor, with the key switch on, should the oil psi light be "on" in the dash, or should it be off?

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Answered in 11 minutes by:
12/5/2012
TIM
TIM, SERVICE MANAGER
Category: Jeep
Satisfied Customers: 6,277
Experience: CHRYSLER SERVICE MANAGER 20 +YEARS
Verified

OPERATION

The oil pressure sensor uses two circuits. They are:

  • A signal to the PCM relating to engine oil pressure
  • A sensor ground through the PCM's sensor return

The oil pressure sensor returns a voltage signal back to the PCM relating to engine oil pressure. This signal is then transferred (bussed) to the instrument panel on a CCD bus circuit to operate the oil pressure gauge and the check gauges lamp. Ground for the sensor is provided by the PCM through a low-noise sensor return. When unplugged -- light should come on. Any more info required--please let me know?

Customer : Should the light come on without the engine running, but with the key on ? My problem is this. I have a 2002 Jeep Liberty Sport, and the engine oil light started coming on intermittently. I made sure that the engine had enough oil. It did. I visually checked the engine oil pressure sensor, and found that it was leaking engine oil. Based on past experience, an external leaking sensor could also mean that it is not functioning properly. The oil was leaking "through" the sensor. I installed a manual pressure gauge, and with fresh 5w-30 engine oil and a filter change, with hot oil, the pressure reading at idle was 30psi, and at 3000rpm it measured just under 90psi. The engine appears fine. I replaced the sensor with an aftermarket unit from Canadian Tire. The problem seemed to go away, until I went for a little road test. The engine low oil light came on again together with the chime, and would continue to do this intermittently every 5 minutes or so. The sensor plug in was soaked with oil, which I cleaned out with component cleaner, but there is s till some engine oil in the connector. I am unsure as to where to go now. How sensitive is this 5 volt system, with an oily connector? Should I try grounding the one wire separately? What do you suggest?

TIM : -- Ok this is a exactly what is going on -- engine oil pressure is fine based on readings-- issue is the connector with oil in it or possibly the new sensor--clean connector good and try it again-- you are %100 on the right track. Please let me know after cleaning it again if it solves your concern?

Customer : Is this sensor fussy as to orientation when screwing in into the block. What I mean is, does the lock on the connector need to be facing upward, or downward, or does it matter ?

TIM : Sensor location as far as screwing it in does not matter. I would just clean connector and sensor-- plug it back in and see what goes on -- if it still acts up-- have them give you another sensor-- sometimes aftermarket parts are not the greatest. Keep in mind-- as with all engines-- if we have oil light on and REALLY lost pressure it would tick/knock--- so this is just a sensor issue. It will be the sensor or the connection.

Customer : I cleaned the connection thoroughly and put in some dielectric grease, but it did not fix the problem. I guess the next step will be to try a new "genuine" Jeep sensor. However I would sure like to know what the Harness connection readings "should" be with the harness connector unplugged and the key "on" ? I have ground on the LH wire, but I have a 5 volt reading on both the center and RH pins. What should the readings be ? Also, is there any way to turn that light off ? Which wires should you be able to cross to turn the light off ? I tried some combinations last night, but to no avail. Only created some new faults in the system causing the check eng light to come on, in addition to the low oil psi light. Last but not least, is there more than 1 pt# ***** the sensor ? I only have an idiot light, not a gauge.

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CAVCIRCUITFUNCTION
1K6 18VT/WTSENSOR REFERENCE VOLTAGE B
2G60 20GY/YL (DIESEL)ENGINE OIL PRESSURE SENSOR SIGNAL
2G60 18GY/YL (GAS)ENGINE OIL PRESSURE SENSOR SIGNAL
3K4 18BK/LBSENSOR GROUND

this is connector pin out

CAVCIRCUITFUNCTION
1K6 18VT/WTSENSOR REFERENCE VOLTAGE B
2G60 20GY/YL (DIESEL)ENGINE OIL PRESSURE SENSOR SIGNAL
2G60 18GY/YL (GAS)ENGINE OIL PRESSURE SENSOR SIGNAL
3K4 18BK/LBSENSOR GROUND
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OPERATION

The oil pressure sensor uses three circuits. They are:

  • A 5-volt power supply from the Powertrain Control Module (PCM)
  • A sensor ground through the PCM's sensor return
  • A signal to the PCM relating to engine oil pressure

The oil pressure sensor has a 3-wire electrical function very much like the manifold Absolute Pressure (MAP) sensor. Meaning different pressures relate to
different output voltages.

A 5-volt supply is sent to the sensor from the PCM to power up the sensor.
The sensor returns a voltage signal back to the PCM relating to engine oil
pressure. This signal is then transferred (bussed) to the instrument panel on
either a CCD or PCI bus circuit (depending on vehicle line) to operate the oil
pressure gauge and the check gauges lamp. Ground for the sensor is provided by the PCM through a low-noise sensor return.

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Customer reply replied 4 years ago

Thanks for all your help, but can you tell me what the voltages should be on the pins on the harness plug that you just identified, "unplugged"?

I know that the one pin is ground, and it is. The center pin that you identified is 5V sensor "in" voltage, but I am getting 5V on the third pin as well! This is with the key switch "on", and the harness "disconnected" from the sensor.

5 volt on two and ground on black wire when unplugged.

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Customer reply replied 4 years ago

Well I guess I have a wiring problem then, "or" a module problem, because I have 5 volts on cavity 1 "and" cavity 2, when unplugged. Any advice for that? I think I may need to get this thing scanned by my local Dodge dealer.

Then that is correct-- the wires are touching -- if you have an ohm meter - you can verify this== also trace wiring back from connector to see if damaged (touching together).

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Customer reply replied 4 years ago

Where exactly is the PCM, so that I can disconnect the harness from it and perform the test properly with the ohm meter. Not sure if it is a harness or the PCM. More specifically, which connector on the PCM would be the one carrying these wires.

POWERTRAIN CONTROL MODULE C2 (GAS) - WHITE 32 WAY

CAVCIRCUITFUNCTION
1--
2--
3--
4K11 18WT/DBFUEL INJECTOR NO. 1 DRIVER
5K13 18YL/WTFUEL INJECTOR NO. 3 DRIVER
6K38 18GY (3.7L)FUEL INJECTOR NO. 5 DRIVER
7--
8--
9K17 18DB/TN (2.4L)IGNITION COIL NO. 2 DRIVER
9K92 14TN/PK (3.7L)COIL ON PLUG DRIVER NO. 2
10K20 18DGGENERATOR FIELD
11--
12K58 18BR/DB (3.7L)FUEL INJECTOR NO. 6 DRIVER
13--
14--
15K12 18TNFUEL INJECTOR NO. 2 DRIVER
16K14 18LB/BRFUEL INJECTOR NO. 4 DRIVER
17K173 18LGCOOLING FAN RELAY CONTROL
18--
19C18 18DBA/C PRESSURE SIGNAL
20--
21--
22--
23G60 18GY/YLENGINE OIL PRESSURE SWITCH SIGNAL
24--
25--
26--
27--
28--
29--
30--
31K6 18VT/WT5 VOLT SUPPLY
32--
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The PCM is located in the engine compartment near the battery graphic

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This is the middle connector.

graphic

TIM
TIM, SERVICE MANAGER
Category: Jeep
Satisfied Customers: 6,277
Experience: CHRYSLER SERVICE MANAGER 20 +YEARS
Verified
TIM and 87 other Jeep Specialists are ready to help you
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Customer reply replied 4 years ago

Thank you so much for all your help.

I will try to resolve based on your information.

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TIM
TIM
TIM, SERVICE MANAGER
Category: Jeep
Satisfied Customers: 6,277
6,277 Satisfied Customers
Experience: CHRYSLER SERVICE MANAGER 20 +YEARS

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