So why doesn’t my timer count down?
It's an HKS type 0.
All settings, functions, & voltage display, seem to work.

Wired:
red - batt
green - IG1
blue - Acc
gray - handbrake
brown - cruise control green/red

So- What am I missing?

 

Only thing I can think of is to make sure the ignition wire you have it hooked to is a cranking power and "ON" power but no power when key is removed.

 

The circuit I'm suspicious of is the hand brake wire.
The RX-7 hand brake signal grounds with the brake off, but I have no idea if that’s what the HKS needs.

 

Well, in both of the cars I have used with turbo timers I didn't even bother with the hand brake wire. Try grounding it and then try taping it off and see if it works. I dunno about you but if the car is ever running I remember to set the brake anyway.

 

holy, it is THE Cosmo Donk also known as fujikotddfshgh..... ?

 

I have tried with the hand brake (gray) wire connected, open, grounded - still no countdown.

The brake warning light still lights until the hand brake is released, so I assume the switch is good.

I'm not very confident with the hand brake "scotchlock" connector.
I probably should solder it like the others..