I have this discontinued HKS boost gauge, black face/ orange lettering, I got from JHOT on eBay. It came with everything, sensor, wiring harness, vac hose, etc. BUT some sort of wiring diagram/ manual.

Below are pics....
1st Pic: the gauge
2nd Pic: the plug leading to the sensor, which is already mounted

3rd Pic: MYSTERY WIRES---- Does anyone know where the BLUE, PURPLE, and BROWN wires go? Haven't found a thread with solid answers, nor is there a readily available online manual...

4th Pic: FYI the two blue wires in the 3rd Pic branch from one blue wire
5th Pic: these are okay, but correct me if I'm wrong----
Black = ground
Yellow = illumination
Orange = constant 12v
Red = switched 12v

The wires in the 3rd pic are my only roadblock.......

 

no help from me, just commenting on a nice boost guage.... matches the stock guages!

 

my guess is that those are for warning, playback, or something along those lines. the question is, where do I connect them?