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It is unlikely any bad electrical problems or computer problems. First has any after market alarm systems been installed? If there has been 90% of the time this is the root cause of the malfunctions. If everything is factory and nothing has been modified You need to focus on the unlock detection switches in the doors. The computer is seeing the switches shorting to ground and the computer sees this as someone trying to lock or unlock the door. Usually I find corrosion or water contamination in the detection switches or the connectors. Depending on your exact configuration( theft deterrent or wireless door locks) you may have detection switches in all four door actuators or just the front doors. I have seen the rear door actuator detection switches go bad before. They cause all kinds of weird locking and unlocking scenarios like you are describing and they can be difficult to diagnose and determine which one is causing the problem. Click the link below for the wiring diagram.
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Thanks for the downloads. I'll bring them to our car place. There is no alarm system, and the locks don't even work with the factory remotes. From what I understand, they did check all switches and connectors in each door after they were going to replace the accuators, but the same problem occurred. They worked....and then they didn't.
We weren't aware of the problem when we bought the car, but it had a short bumper to bumper warranty so we thought we should get it fixed while the warranty was still good. Since they couldn't fix the problem, they sent the car to a Toyota dealer...where they couldn't find or fix the problem and came back with wanting to replace the computer! The place where we bought the car is actually willing to buy the car back from us if we want. Although a bit irritating and a little inconvenient, power locks aren't a big deal to me. My concern is the possibility that it could lead to bigger problems...as I stated before, as I had read that this was a pre-cursor to automatic acceleration. YIKES!
I would take the buy back If I were you.
I will be off line and unavailable for any follow up questions or replies from 9/11 until 9/22. I am in Iquitos Peru and headed out in the morning on a medical missions relief team into the Amazon jungle. Thanks for your patience while I am assisting those in need.
PS I have not found a way to get the Internet in the jungle. YET!