Hello, I have a toyota previa 94, How the reservoir oil tank works, this appears to have no function, The level does not change. The engine has an oil leak but the reservoir level remains the same while the engine level is down.

Did you prime the new pump with some engine oil? Another trick is to use some light grease to coat the pump gears so they will seal against themselves. If you primed the pump and are sure the pump is working, you may have worn out engine bearings or some internal oil leak that is keeping the oil from getting pressure.

looks like you have it full. it should hold between 4 and 5 quarts. your problem is elsewhere.

most of these models have 2 oil lights.The red one is oil pressure,if flashing or on when engine is running,it is usually serious.check oil level,but usually caused by blocked pickup screen(a common toyota fault) when services aren't done.The orange oil light is tripped by an oil level sensor on the side of the sump when the oil level is low.If the oil level is ok,note this is a common fault especially if oil changes have been missed,and/or a petrol engine oil used and sludge builds up,sometimes using an additive for flushing prior to oil change can help,but may not work on 1st oil change.

No, this is a power steering issue. Are you certain the power steering fluid level is correct? The squeeling noise is caused by air in the power steering pump. The leak must be repaiored, usually by replacing the pump, unless it is just a leak in the reservoir.

tienes alguno problama con el flotador para el nivel de aceite automaticl,creol el grifo de nivel automatico falten nuevo juntas tambien el flotador es roto despuces el aceite llenado el motor

Hello. Welcoem to FixYa.

Unfortunatly, the answer is no.

Toyota does not fit oil level sesnors to any of its passenger automobiles.

The only Toyota product that did have an oil level sensor installed was the Previa model.

If the light is flashing there could be problems with the electrical wiring. The easy places to check are at the bottom of the oil reservoir (pass. side under the hood) and at the driver side of the oil pan under the vehicle where the wires plug into the sensor. If this doesn't resolve the problem then it isn't easy, and testing the circuit will have to be done by someone who knows their electrical "stuff." Even the pump motor for the reservoir could be out.

If the Oil Level Sensor light stays on and you have already checked to make sure the oil level read on the dipstick under the driver side seat engine compartment is reading adequate, then you have a sticking oil level sensor float. Replacing the oil level sensor is easy, but extremely expensive ($485 in 2012). You can try to clean the plastic spool that the float slides on, but the problem is usually that it has swollen or expanded (likely from heat in the oil). One could try to sand it down but this would be difficult. I have made a new part out of nylon 6/6 on my lathe and replaced the plastic spool so far with excellent results. I'm considering selling it as an aftermarket part when I see if mine works. It would be a lot less than $485 dollars from Toyota. Or possibly have people send it to me and I'll repair the sensor myself.

the oil should be black,brown or gold(new) with no other colors in it. shouldnt be milky or streaky. the trans fluid should be light red or semi light red.as for the engine being oily its hard to discern unless you rinse it off to metal and drive it. if you mean the oil pan has black oil on it then it may be ok.

If you are takling about the external oil tank, you don't need the pump, you need to replace the oil tank level sensor.
Common problem.

When you say "warning light is on", I assume you are not talking about the oil pressure gauge...
If not, here is your solution:
What you have is a very common problem: The oil LEVEL sensor has failed. Previas have 2 sensors; pressure & level of the oil in the pan...What you need to do is replace it, Toyota part number : 89491-28030.
BUT...This part is $380.45. Not cheap; Sorry but true.