Can't lock doors with Remote

I assume you mean when you try to lock ... it goes through the locking motions and then a couple seconds later unlocks again.

That's what it does if it can't detect one of the doors going fully to locked ... usually because the lock motor on that door is worn out. If any door did not fully lock, the car unlocks again to make sure you don't walk away thinking it successfully locked.

Because the driver's door lock motor is the one that gets used most over the car's life, it is almost certainly the one that's shot. If you stand outside the passenger side of the car and watch through the window while you try to lock with the remote, you'll probably see the driver's lock button move only part way or even not at all. There's your shot lock motor for you.

Assuming you do confirm it's the lock motor on the driver's door, you've got some options:

1. Get the right part and replace it. Least fuss, all fixed, but the part's about $100.
2. Look on eBay for knockoffs of the same part. Strangely, you don't find many if you search for Prius, but the same part number is used in some Lexus GS300, GS400, and GS430 cars and if you search eBay for "left front lock actuator gs300 gs400 gs430" you'll find options for about $16. I just received one today and it does fit and basically work, but has a couple issues I still have to write up.
3. In many threads on PriusChat you'll see people buying just the electric motor inside the actuator (apparently it's about $7), carefully prying/cutting/dremeling open the sealed plastic actuator case, replacing the motor, somehow fixing the case back together and reassembling. That's the least money and the most fussing around.

-Chap

 

I finihed writing up what I found about the $16 eBay actuator I bought. You can see the write-up here.

-Chap

 

Chap, I had this exact problem on my 2010 (Gen 3) Prius on the driver's door. The part for the Gen 3 is $230 (69040-47060). I replaced it today, and the door will lock from the fob, the exterior door handle, and the lock button on the interior door panel. I have 71,000 miles, and about 5 1/2 years with the car.

 

Easy to test. Roll down drivers window. From outside reach in and hit lock button on drivers armrest. Walk around car and check doors. Did all lock? Hit unlock, walk around, did all unlock? If everything works here, problem is with wireless remote system.

If doors did not lock or unlock "manually" dong steps above there is something wrong with 1 or more door actuators.

 

of course with this car the engine has to be running in order to roll down the window!

 

Um, that's not true. With key in "accessory" position the windows are operable, even if car is not in "Ready" mode. I do know about the "open window with key" feature, but I've not tried on my '02.