My Apexi turbo timer will turn on for a split second when I start the car, but doesn't stay on.

I've got it grounded etc, where should I look for the problem?

Your issue might be around the ignition, did you use a harness? or did you actually splice wires, both? I guess if you offer more information on your setup trouble shooting for others would be easier.

Using the HKS harness. I've got three wires leftover after plugging into the factory harness: red, black, and grey. From what I recall grey is the ebrake cable, black is ground, and I'm not sure what the red wire is for.

Now does the grey ebrake wire need to be connected for it to run, or is it just a precaution?

I've read two different sets of instructions for where to plug the HKS harness into even, is it the plugs in behind the radio, or by the alarm module under the steering column?