Previa Auxiliary engine oil reservoir operation?

[SamPrevia]

Hi all,

OK, this is embarrassing. I don't know the operation of the Previa auxiliary oil reservoir. I have checked the 1997 Previa Owner's manual but could not find any useful information besides checking and adding oil when needed.

So how does it work? Exactly when is oil pumped to the crank case? What triggers the transfer? If oil is transferred when needed, why the need for checking the crank case dip stick?

How often does the oil in the reservoir need to be changed?

Thank you in advance for your explanation.

[pdgizwiz]

There's a float-type oil level sensor in the sump. If the oil gets low in the sump, the sensor sends a signal to the computer and it turns the pump on until either the float switch changes state or some time interval goes by. Something like that.
Trouble is - the level sensor can fail. Toyota wants $350 for a new one, so at that point, rather than risk having the system over fill your crankcase, it becomes preferable to cheapskates like me to just get used to going through the odd but simple motions of accessing the dipstick and then just monitoring the oil level directly as if it was a normal car. The Previa isn't a normal car, but that's why I own so many of them!

[SamPrevia]

Thanks. So you disable the pump once the sensor fails?

[pdgizwiz]

To tell the truth, I never got around to doing that, although that's the next logical step. I just pulled the oil out of the reservoir and ignored the occasional whirring noise that the pump makes. After that I sold the van to a buddy and told him that if I ever found another float switch I'd swap it out for him. I have one now and am waiting for him to need an oil change, at which time I'll do the swap and cross my fingers.