Need Wiring for A/F ratio gauge. Please Help

[Coupe_Devil]

I need a wiring solution for a A/F (Air/Fuel) ratio Gauge. any help would be great. thnx.

[niznos]

Should be basically 3 wires: switched power, ground, and O2 sensor, don't know the model of gauge you are using, or the model of car, so this is as good as an explaination as it's going to get.

[Coupe_Devil]

I'm trying to install an APC A/F ration gauge in my nissan 240sx. The 5 wires are as listed...

(1) white ALONE(1) green ALONE(1) black ALONE(1) black RAN WITH RED(1) red RAN WITH BLACK

the red and one black are ran together with a harness at the end. The other have of the harness came with it with some wire so you can splice and have as much wire as you need.

[niznos]

First, you'll want to look in your install guide that should have came with your gauge to see what each color goes to what. If it does not come with a guide, you'll want to get a hold of the manufaturer or the seller of the gauge.As far as the wiring goes, you'll certainly have a ground wire. This ground should be ran to any good ground in the dash or engine bay. Easiest would be in the dash, and it can be shared with the radio head unit and devices like that. Same goes for the power. Your radio head unit will most likely have 2 power sources. One is constant, and the other switched, you will want to power the gauge with the switched power wire. 3rd would be a signal wire from the oxygen sensor. Do not splice this one in at the sensor, run that wire to the ECU and splice in at the ECU harness. If you splice in at the sensor it will introduce a non-shielded wire where it matters most. That non-shielded wire will pick up interference from the ignition system and make your readings off at best, or your car will not run at all in the worse case senario.As for the 4th and 5th, you'll have to check the guide once again. I used an Autometer gauge and it only needed 3 wires. My guess is that they are for the intrument/ dash lights so the display lights up for night driving.