Electrical problem
1997 Ford Taurus 6 cyl Front Wheel Drive Automatic 150K+ miles
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First problem: courtesy lights above RView Mirror occasionally won't go off after car is put in drive; concurrently, the automatic electronic door locks fail to lock. I gave up and disconnected the wires, as it posed a safety issue at night.

Second problem: P155 error reported; sensor was replaced, but the error persists. I was told it should clear after some driving time, but it's still there months later.

Third problem: On occasion, Speedometer suddenly cuts out, dropping to zero while car is still going. Turning cruise control on doesn't provoke this, and it had been working reliably prior. But now attempting to engage the cruise control after powering it on provokes the speedometer to cut out. Loss of speedometer also affects automatic transmission behavior, since it clearly has no idea what speed the car is actually moving at.

Fourth (and biggest) problem: Engine will periodically refuse to start. It turns over, but no spark is coming to the plugs. Let it sit for 10 days or so, and it miraculously resurrects to life and will start. I'm convinced this has to do with a defect in the cruise control and how it affects the car's main computer, but Ford will not acknowledge such a defect exists in the Taurus.