Hi all,

OK, so I'm in the process of wiring up my head unit and Defi gauges. Each call for an illumination wire, but as I understand it the FD uses PWM to modulate the pulses of the ground to control intensity of the lighting, which isn't what I want. I don't care about the dimming feature - in fact I want to AVOID it as I think it's annoying since I keep my brightness on full 100% of the time and never adjust it down. As such, there are two wires in the illumination harness: red/blue and red/green (see diagram below)

So here's my question: There's obviously a +12v that feeds all of the illuminated components, and then all of those components are grounded out back to the PWM controller where the signal is modulated. So, I don't want to be connected to the modulated ground side, I want full +12v brightness all of the time regardless of the dimmer strength. If I tap into R/B, will that achieve the desired effect?

Thanks in advance, you're all sexy.

 

This may or may not help: I have SPA gauges. I bundled together the hot leads in a spade fitting which I installed in the unused hot slot at top right of the fuse box by the dead pedal. Then I grounded to the chasis behind the kick panel by the dead pedal. Simple, quick and fully powered when the key is in the run position.

 

I went through all of the previous threads about illumination when I hooked up my DEFI racer boost gauge. I finally decided to use the illumination wire from the ashtray and it works perfect!

 

^ What he said, I use the same method to feed all 4 of my gauges, works great!

 

the ash tray wire is the way to go

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/some-defi-standard-gauge-install-%2Afacts%2A-239260/

 

Not helpful but I appreciate it.

Why is everyone saying "ash tray wire". There are TWO ashtray wires: red/green and red/black. If you inspect it, they turn into the same red wire after the connector due to lack of polarity needed for bulbs. I guess since everyone is parroting the same thing I'll just try one and hope it works. I think I'm going to pick red/black after studying the schematic.

 

filament bulb doesn't have polarity, you are supposed to wire your bulb in parallel with the ashtray bulb instead of taking just one wire.

 

I just wired in two pillar mounted gauges. I took the earth from the new gauges and ran it under the dash to a well grounded small bolt, with an eyelet/loop crimp end.

Then took the 12V +ve wire and ran it to the ashtray bulb. I found that of the two red wires on the ashtray bulb, one was earth, and wouldnt work. So tried the other wire, and hey presto, 12V +ve, switched on/off with the rest of the instrument lights. Couldnt be easier.

Not sure about the pulse-width-modulation comment by the OP. Doesnt seem to be a contributing factor for me. I run my autometer gauges with the ashtray 12V +ve and a good earth. With the instrument cluster on full brightness, the illumination is the same brightness across all the gauges. I hate seeing different color instrument cluster gauges and aftermarket ones, so my Autometer Sport-Comps use the red bulb covers and they match the red instrument cluster illumination really well.