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Oil sending unit

Oil pressure gauge is erratic. I disconnected wire at sending unit and checked for continuity. It shows wire is grounded. Should it be grounded and if not should I run new wire to dash gauge cluster?

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  • Steve Lucas Oct 29, 2012

    There is only one wire on the sending unit and it shows it is grounded when the key is off and I dont think it should be.

  • Steve Lucas Oct 30, 2012

    Thanks but I have replaced it twice, same problem.

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  • Cars & Trucks Master
  • 4,340 Answers

Hi Steve,

You may or may not have an issue with the wire, as per your description...
BUT, most issues are the sending unit. They are replaced diagnostically. You need a special socket to replace it, so buy one at the parts store. This need not be a dealer item. anyways, 99% of the time the sender fails.

Posted on Oct 30, 2012

Testimonial: "Thanks. will replace again."

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SOURCE: 1993 Jeep Grand Cherokee, V6. Oil Pressure Gauge Read High.

it could be the sensor you should look at the oil pressure relief valve

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SOURCE: 1984 Chevrolet 454 oil pressure gauge reads maximum all the time.

faulty gage,replace

Posted on Jun 17, 2009

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SOURCE: 2002 Jeep Grand Cherokee 4.0L oil pressure gauge reading too high

if the gauge starts a 0 - goes to 1/2 , than full - sounds like gauge is OK - seems to me like the sending unit is bad - you could try removing the sender and trying to clean out the port with "brake clean", letting it dry than re-installing it. the pressure switch is still the least expensive place to start

Posted on Oct 27, 2009

moparownr
  • 667 Answers

SOURCE: oil pressure gauge shows no pressure when its cold

Jim, I think your oil pressure sender is going bad, you should replace it and see that your oil pressure is in fact good, you can also check and verify the wires to it at the same time. It is located next to the oil filter. Hope this helps, let me know

Posted on Dec 09, 2009

Testimonial: "Thank's for the info, I installed a new oil sensor and it works great. Thank's again"

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1 Answer

Where is the oil sending unit on a 1996 mercury cougar xr7 ? Its cause my oil pressure gauge is bouncing up and down...i dont know why...can anybody please help me thank you so much


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The low oil pressure warning lamp will illuminate anytime the ignition switch is turned to the ON position without the engine running. When the engine is running, the light also illuminates if the engine oil pressure drops below a safe oil pressure level. To test the system, perform the following:
If the oil pressure light does not work, perform the following:
  1. Turn the ignition switch to the ON position.
  2. If the lamp does not light, check for a broken or disconnected wire around the engine and oil pressure sending unit switch.
  3. If the wire at the connector checks out OK, pull the connector loose from the switch and, with a jumper wire, ground the connector to the engine.
  4. With the ignition switch turned to the ON position, check the warning lamp. If the lamp lights, make sure the oil pressure switch is properly grounded in the cylinder block, and if so replace the oil pressure switch. If the lamp still fails to light, check for a burned out lamp or disconnected socket in the instrument cluster.
To diagnose an oil pressure light that stays on, perform the following:
  1. Check the engine oil level and top off as necessary. If the engine was 2 or more quarts low on oil, test start the engine after topping off the oil level and recheck the oil pressure light operation. If the light stays on, stop the engine immediately and go to the next step.
  2. Disconnect the wire at the sending unit, then turn the ignition switch to theON position. If the light remains on, check the wire from the sending unit to the gauge for being shorted to ground and repair as necessary. If the light goes out, turn the ignition switch OFF and go to the next step.
  3. Replace the oil pressure sending switch with a known good switch.
  4. Start the engine and check the oil pressure light operation. If the light stays on with the engine running, stop the engine immediately to avoid severe engine damage until the cause of the problem can be determined.

WARNING
If the oil pressure light remains on while the engine is started, stop the engine immediately. Do not operate the engine until the cause of the problem can be determined. Operating an engine with low oil pressure will cause severe internal damage.

Possible causes for an oil pressure light to stay on are:


Pinched or grounded sensor wireDefective oil pressure sending unitRestricted or severely leaking oil filterExcessive internal engine bearing clearance.Insufficient or severely contaminated engine oilBlocked oil pump pickup screen or severely worn oil pump

Mar 31, 2016 | Mercury Cars & Trucks

1 Answer

Having oil pressure problems


The sending unit is a variable resistor. When the oil pressure is normal only a small amount of voltage goes to ground through the sending unit. As the oil pressure goes down, more voltage is shunted to ground reducing the sending unit voltage and causing the gauge to indicate a lower pressure. If the oil pressure falls very low or disappears the sending unit shunts all the voltage to ground which causes the dash indicator to show no oil pressure.
Now if the wire to the sending unit gets nicked, melted or cut and finds a short circuit to ground, or gets disconnected in a junction point between the gauge and the sending unit, you will get the same no oil pressure indication from the gauge.
Check you wiring for a short to ground or an open connection.
The same

Aug 25, 2012 | 2004 Chevrolet TrailBlazer

1 Answer

2005 Chevy Silverado show low/erratic (0-20 lbs) oil pressure.


More then likely the sending unit is faulty, but to be safe hook up a mechanical test gage at the oil pressure sender port and check oil pressure hot engine, if it is steady then replace the sending unit.

Jul 28, 2017 | Chevrolet Silverado 1500 Cars & Trucks

1 Answer

Where is the oil pressure switch/sendor located?


Oil pressure can be checked at the sending unit passage with an externally mounted mechanical oil pressure gauge. To get accurate results from the test, make sure you follow the manufacturer's recommendations and compare your findings to specifications.
Testing the Oil Pressure Gauge
  • Test the gauge by grounding the wire that leads to the sending unit on the block.
  • When the wire is disconnected from the sending unit with the key switch on, the needle on the oil pressure gauge should be either all the way high or all the way low. Grounding the wire should make the needle move to the opposite side of the gauge from where it was before the wire was grounded. If the vehicle is equipped with an oil pressure light, touching the wire to ground and then removing the wire from ground should turn the light on and off.
  • If either happens, the gauge and wiring are good and the sending unit is at fault.
Testing Oil Pressure
Pressure can be tested by temporarily installing an oil pressure gauge in place of the sending unit. Before testing, look up the oil pressure specifications for your vehicle in the appropriate service manual.
  • Bring the engine up to operating temperature.
  • Now shut the engine off.
  • Locate the oil pressure sending unit; usually it is on the lower side of the engine block.
  • Disconnect the wire from the sending unit and use an open ended wrench to remove the sender. Using pliers can damage the unit.
f43-19.jpg An oil pressure sending unit is removed with a special socket. Courtesy of Chrysler Corporation.
  • Tighten the oil pressure test gauge into the hole in the block where the sender was removed.
f11-15_3184.gif Measuring oil pressure. Reprinted with permission.
  • Check the engine's oil level and fill, if required.
WARNING Be extremely careful when working near a running engine. Always wear safety goggles or glasses with side shields when working around moving machinery and be sure that your clothing is not loose.
  • Now turn the engine on and check the oil pressure on the gauge.
    • Watch as the engine warms to note any excessive drops due to temperature.
    • Make sure the engine speed is set to specifications for testing pressure.
    • If necessary, us a tachometer and adjust the engine idle speed.
  • Record the measured oil pressure, then turn off the engine.
  • Compare the test results with the manufacturer's specifications.
    • If the oil pressure is within specifications, this shows that the oil pressure sending unit may not be working correctly.
    • In many cases, replacing the oil sending unit will correct the problem.
  • After the test is complete, reinstall the oil pressure sending unit, start the engine, and confirm there are no leaks.

Nov 20, 2010 | 2002 Pontiac Bonneville

2 Answers

My h2 oil pressure gage goes up and down from cero to 80 while runing, is this normal???


OIL PRESSURE GAUGE SHOULD HAVE STEADY READING.IF FLUATING I WOULD HAVE OIL PRESSURE CHECK SOUND LIKE FAULTY OIL PRESSURE REGULATOR.

Aug 22, 2010 | Hummer H2 SUT Cars & Trucks

1 Answer

02 cherokee losing oil pressure when accelerating, fine at idle.


Was the sending unit an aftermarket part?We like to install the original part back into most vehicle, but because of people price shopping, this can cause some issues. If the switch is working properly, the gauge should rise as the engine RPM's increase as you stated. With the key on and the engine off, disconnect the sending unit wire and ground it. The gauge should go to the highest reading, and that checks the wire, and the gauge. I suspect that the sending unit is failed or not the proper one for your vehicle.

Jan 07, 2010 | 2002 Jeep Grand Cherokee

1 Answer

Oil light blinks on and off could pressure switch be bad if so where is it located on a 2000 ford windstar 3.0


Oil Pressure Switch Operation:
00134_oil_pressure_switch_gauge.jpgInformation relay unit for the indicator light or gauge on instrument panel. It contains a diaphragm that responds to changes in oil pressure. When the oil level is over a pre-set limit, the diaphragm opens the switch, turning off the light. When level is below the pre-set limit, the dash light comes on. In later model cars, if the oil pressure drops, the switch turns off the fuel pump, to stop the engine and limit damage to internal parts. Oil pressure switches can be grouped into two categories, units for electrical gauges and for mechanical gauges.

Oil pressure can be checked at the sending unit passage with an externally mounted mechanical oil pressure gauge. To get accurate results from the test, make sure you follow the manufacturer's recommendations and compare your findings to specifications.
Testing the Oil Pressure Gauge
  • Test the gauge by grounding the wire that leads to the sending unit on the block.
  • When the wire is disconnected from the sending unit with the key switch on, the needle on the oil pressure gauge should be either all the way high or all the way low. Grounding the wire should make the needle move to the opposite side of the gauge from where it was before the wire was grounded. If the vehicle is equipped with an oil pressure light, touching the wire to ground and then removing the wire from ground should turn the light on and off.
  • If either happens, the gauge and wiring are good and the sending unit is at fault.
Testing Oil Pressure
Pressure can be tested by temporarily installing an oil pressure gauge in place of the sending unit. Before testing, look up the oil pressure specifications for your vehicle in the appropriate service manual.
  • Bring the engine up to operating temperature.
  • Now shut the engine off.
  • Locate the oil pressure sending unit; usually it is on the lower side of the engine block.
  • Disconnect the wire from the sending unit and use an open ended wrench to remove the sender. Using pliers can damage the unit.
f43-19.jpg An oil pressure sending unit is removed with a special socket. Courtesy of Chrysler Corporation.
  • Tighten the oil pressure test gauge into the hole in the block where the sender was removed.
f11-15_3184.gif Measuring oil pressure. Reprinted with permission.
  • Check the engine's oil level and fill, if required.
WARNING Be extremely careful when working near a running engine. Always wear safety goggles or glasses with side shields when working around moving machinery and be sure that your clothing is not loose.
  • Now turn the engine on and check the oil pressure on the gauge.
    • Watch as the engine warms to note any excessive drops due to temperature.
    • Make sure the engine speed is set to specifications for testing pressure.
    • If necessary, us a tachometer and adjust the engine idle speed.
  • Record the measured oil pressure, then turn off the engine.
  • Compare the test results with the manufacturer's specifications.
    • If the oil pressure is within specifications, this shows that the oil pressure sending unit may not be working correctly.
    • In many cases, replacing the oil sending unit will correct the problem.
  • After the test is complete, reinstall the oil pressure sending unit, start the engine, and confirm there are no leaks.




Nov 17, 2009 | 2000 Ford Windstar

1 Answer

My Oil Pressure gauge is working erratic, want to replace the sender, but where is it? V6 3.0 auto 2wd


It's on the right(passenger) rear corner. It has one wire connected to it. To verify that you have the correct sending unit, if you disconnect the wire and start the engine, the oil pressure gauge will either stay at 0 or will peg out.

Sep 24, 2009 | 1993 Ford Ranger SuperCab

2 Answers

Oil Pressure going up and down during acceleration and decel.


Check your oil level in the engine. Oil pressure will read this way when the oil level is getting low...

May 27, 2009 | 1987 Porsche 944

1 Answer

My 01 bonneville oil pressure gauge is showing 120 and my gas gauge is all over the place


HI, the oil pressure sending unit may be malfunctioning at this point. this will cause erratic readings. if your oil level is proper and there are no apparent oil leaks, you will need to replace the oil pressure sending unit. this will fix the erratic oil pressure readings.

Concerning the gas gauge. this device also has a sending unit that sends the correct fuel level reading to the gas gauge via wire transfer. this sending unit is located and attached to the fuel pump assembly inside the gas tank. replacing this device will fix this issue as well.

Please rate and god bless:)

Apr 28, 2009 | 2001 Pontiac Bonneville

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