So I just installed a pair of DEFI BF gauges - oil and water temp. This system is controlled by the control unit II which has four wires for hookup.

1) Ground - tapped off the ground for the ashtray light
2) Illumination/Dim - tapped off the ashtray light power
3) Switched power - used a spade connector to plug into the switched power on the upper right of the kick panel fuse box

All of the above work perfectly. Now for #4 the constant power. While not absolutely needed (since you can just use switched power again which is how the gauges are working now), without constant power the gauges don't do their power down sequence and recorded data isn't saved on the control unit.

I was under the impression that the connection to the left of the switched power on the fuse box was supposed to be constant power, but either that is not true at all or it is not functioning on my car (checked with multimeter).

So where should I steal constant power from given that access to my radio wiring is not an option? I was thinking maybe a fuse tap, but which fuse?

 

Obviously, this question is close to this thread:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/defi-gauge-wiring-12v-constant-614747/

But the question is not answered there. They just say use the switched power off the fuse box (like in dgeesaman's writeup, which doesn't actually fix the problem) or radio wiring which isn't an option.

 

why can't you splice into your radio wiring?

 

I steal all of my signals from my ignition switch. As I remember, constant 12V is seen by the black wire with a green stripe.

 

Nice. I think you may have something there. . .

Thanks

 

Be careful when tapping into ignition wires, as this can cause intermittent starting issues if done improperly.