HFS3/Summer unit installation queries on a 1995 FD3S Mazda RX7

[bdarepat]

I'm just finalising the installation of a HSF3/Summer system in my 1995 FD3S Mazda RX7 and would like to clarify the power connections to the system.

In the schematic diagram below from the Aquamist Forum website, it indicates to connect the red wires of both the HSF3 and Summer unit power connectors to pin 4B of the vehicle EMS connector and the black wires and white wires to pin 4C of the EMS.

However, this does not tally with the EMS pin out of the vehicle wiring diagram for my 1995 RX7, also reproduced below, as on there, pins 4A and 4C are both grounds. I have physically checked the vehicle EMS cable connectors and they agree with the drawing.

Could you please indicate where I should be picking up power and ground?

Also, can you please indicate from which pin on the EMS the 12V@PRE-CRANK signal should be tapped?

The other signals all seem to tally.

N.B. There were at least two versions of the EMS on FD3s RX7's over the time it was in production , (they went to a 16bit ECU post 1996), so perhaps this is where the confusion lies.

Many thanks in advance, Mike Allward

v3-H3 wiring

1992-95 RX7 FD3S ECU pinout

[Richard L]

Any switched 12V at "pre-crank" or "run" key position can be use for the Aquamist red power supply wires.

[bdarepat]

Thank you for the clarification Richard