Could it be an electro-magnetic malfunction?

Dear Car Talk

Dear Car Talk | Jun 01, 1991

Dear Tom and Ray:

My 1989 Toyota Camry station wagon with automatic transmission and overdrive has a flaw. Occasionally, and randomly without warning, the transmission will go into Neutral! This occurs when the car has been run and is hot, and then is parked for some time. Then, when starting to drive again, as the speed increases, it goes from first, to second, and into Neutral. I can get it to go back into gear by disengaging the overdrive. The Toyota people say they have no idea what could cause this, and can't fix it unless they can make it happen while in service (which, of course, it never does). They have promised to fix it for free even after warranty if it ever becomes a more consistent problem, but I'd like to fix it now. This car has otherwise been an excellent performer. Any ideas?

TOM: Well, Peter, we got a letter earlier this week from the Toyota dealer in your town asking the same question, and we couldn't help him either.

RAY: Actually, Peter, it sounds to us like one of the solenoids inside your transmission is sticking. Your transmission is electronically controlled, and there are two solenoids that make the gears shift while you're driving.

TOM: If you were out the day they discussed that in General Science class, solenoids are electro-magnetic switches that make things move when electricity is sent to them. In this transmission, they're used to move the things that make the car shift.

RAY: We don't have enough space here to explain exactly how they work, and besides, it would require us to use our hands. But what we think is happening in your case is that one of these solenoids is sticking. The result is that it's telling the car to go into first gear instead of overdrive when the car is going too fast to be in first. The transmission knows the car is going too fast, so it shifts into neutral to protect itself.

TOM: Ask your dealer to try replacing the solenoids. That's our best guess. If that doesn't fix it, write back and we'll put out an all points bulletin.

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