When I open the front left door, the interior light flashes on and off repeatedly. Where is the sensor that triggers it?

 

Your door latch switch has failed.

 

The switch is adjacent to the door latch?

 

The switch is incorporated in the latch assy.

 

Well it seems to have fixed itself after a long drive on a warm day, may be just a poor connection.

 

The problem is worse when the switch acts up in the later cars with electric 'memory' steering columns and seat 'egress'.
When set to 'AUTO' the steering column jumps up and down, driver's seat moves back and forth along with the flashing interior lights.

Customers 'freak-out' at the bizarre column, seat and light show.