When in gear at stop oil light comes on and engine stalls sometimes replaced sending unit no different where to go next?

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

Not exactly sure about 1999 model but It's usually located next to the oil filter with a wire coming out of it or with in the oil drain area. It's about $12 to replace.
For vehicles with an indicator light, the sending unit is like a simple switch. When the engine is off, or the pressure is too low, the switch closes, and illuminates the lamp. Under pressure, the switch is open and the lamp goes out. The only difference in the above test, is with the wire disconnected, the light is out, and with the wire grounded, the light is on. How an Oil Sender works

2005 Caravan, what engine? Has oil been changed lately? Is there any problem with performance, such as stalling, stumble, hard starting or anything abnormal happening?

LOW OIL PRESSURE WILL CAUSE OIL PRESSURE SWITCH OR SENDING UNIT TO DISABLE FUEL PUMP.CHECK FOR OIL PRESSURE.REMOVE OIL PRESSURE SENDING UNIT SCREW IN OIL PRESSURE GAUGE TESTER INTO BLOCK WHERE OIL PRESSURE SENDING UNIT GOES TURN ENGINE OVER CHECK FOR OIL PRESSURE SHOULD BE 18 PSI @ 2000 RPM. BESURE TO WRAP TEFLON PLUMBERS TAPE AROUND THREADS TO THE OIL GAUGE PRESSURE TESTER OIL WILL SPRAY EVERY WHERE.IF YOU ARE GETTING NO OIL PRESSURE.YOUR OIL PUMP FAULTY.YOUR ENGINE CRANKSHAFT BEARINGS WORN OUT.WORN DAMAGED CAMSHAFT OIL PUMP DRIVE GEAR OR OIL PUMP DRIVE ROD DAMAGED OR BROKEN. IF OIL PRESSURE OKAY OIL PRESSURE SENDING UNIT IS BAD.

Try replacing the oil sending unit, Some years had a fuel pump shut of built in to the switch so if the oil pressure went down it would kill fuel pump to stop engine damage. Yours may be faulty

Sounds to me like it could be a bad oil sending unit or gauge. I would take it in to a shop and have them test the oil pressure with their equipment.
If they tell you the pressure is good try changing the oil sending unit first then if that don't work, replace the gauge.

HI.There are only two possible issue here that will cause this to occur. The first issue will be a failing, or damaged oil pressure switch(sending unit). The sending unit is responsible for transmitting the correct information to the instrument that displays the pressure readings. If there is a wiring issue, or the sending unit has failed, this will cause the oil light to illuminate. In this case, the sending unit must be replaced. Ok, the next issue will be a failed oil pump. This will be the most common issue, in this case, due to the actual mileage on this particular vehicle. A oil pump can fail mechanically(gear failure). This device is not repairable, and must be replaced. The easiest way to isolate the issue, will be to preform a pressure test on the engine. There is a special tool, used by your mechanic, that will allow you, or him, to extract the true pressure readings for the engine, during idle. If the pressure test confirms that the oil pressure is low, or weak, this will lead to a failed oil pump. Now, if the pressure test indicates that the engine is running at optimal pressure range, this will indicate that the oil pressure switch(sending unit), is faulty. It must be replaced.

In order to troubleshoot this problem correctly,you need to clean the motor first.

An intermittent/shorting oil sending unit is the source of the problem.

You need to make sure it's not an oil leak into the oil sending unit first.


After you clean the motor then look for oil leak.


Also make sure the wire from the oil sending unit wire is not touching the engine block.


Oil sending unit is cheap. It's an easy job.


Change it at your next oil change.

It's on the engine, right next to the starter, it has one wire going to it. You don't need to drain the oil. If the light is coming on, you may have bad seals in the oil pan, a fairly common problem, but replacing the switch is a good fisrt step.

when you press the brake pedal the brake master cylinder vacuum booster takes vacuum away from the engine and that slows the idle speed just enough to trigger the low pressure oil light. Pull the oil pressure sending unit out and hook up an oil pressure test gage, if the pressure is above 15 PSI hot engine idle in drive replace the oil pressure sending unit.