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Seat belt fastened circuit Answered

I have designed a circuit the intent of which is to control the seat belt fastened light on the dash.  There are two switches.  1. A pressure switch that closes when someone is in the seat.  2. A Reed switch that closes when the seat belt latch is latched.   Each works correctly separately.  I am using a standard 12V automotive relay to control the light, as below.  Let's just look at one side. 1. When the ignition on the 12V wire connects to the two leads, i.e., the pressure switch and the reed switch. 2. When someone sits in the seat the pressure switch closes and the dash light, which is connected to the relay at 30 and 87A comes on (relay not activated).  3. When the seat belt is latched, the reed switch closes, the relay switches and the current between 30 and 87A turns off. Diodes are introduced in the circuit as shown in the diagram.  The problem is that is does not work correctly.  Sit in the seat and the light comes on.  Buckle the latch but the light does not go off. There is still 12V between 87A and 30, but I don't know why.  I also tried putting a diode between 85 and 86 (pointing towards 86) but that did not help.  Suggestions please.


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