Here's the circuit we're building.
The headlight switch and the passing switch both turn on the headlight. The dimmer switch and the passing switch both flip to the high beam.
To make this work we modify the Mazda wiring in two places. One is on the car side of the connector to the steering column. The other is in the instrument cluster circuit board.
Steering column connector, before:
Steering column connector, after:
At each headlight:
On the instrument cluster, the ground side of the high beam indicator lamp needs to be disconnected from ground (by cutting the trace on the board) and reconnected at "beam indicator output" on the steering column diagram. If you do not make this change, the high beam indictor will turn on whenever the headlights are on, high or low.