A/F Gauge Install [Archive] - SaabCentral Forums

: A/F Gauge Install

20th February 2003, 10:36 AM
Anyone know how to hook up an A/F gauge for my 99 9-3S, like which wires go were.

20th February 2003, 02:52 PM
It is relatively simple. Basically you want to tie into your O2 sensor. So locate the first one coming off of the exhaust right b4 the cat. Follow those wires up until you find an area where they can be accessed (see pictures for where I tied in), and then just splice into it. In the directions for installation it asks if your O2 sensor is heated or not. You have a heated one, like I do, it will have either 3 or 4 wires coming off of it. The wire you are looking for is the signal wire. Most likely that wire will be black in color. If you have 4 wires coming off of it there will be one grey, one black, and 2 white. 3 wires will have 2 white, and one black. Again, you are looking for the black one. I then followed the wire up so that I could find the optimal place to splice into it. Spliced in and then ran the wire through the firewall. If you pull up your carpet where the pedals are, back underneath and behind the pedals you should see a rubber stopper that plugs a hole in the firewall. I just popped it out and ran my wire and my hose through that hole. Finally I tied into the dash lights for the 12V power supply and that was it. I used the dimmer switch so that I could control them with the dash lights. Once you pop out the dimmer switch there are wires that you can splice into. Use any one of these:
Grey/Red - Interior Lighting
Violet/White - SID
Violet/White - Instrument Illum.
Grey/White - Interior Lighting
Grey/White - Heater Illum.
Green/White - Power Supply to Switch
Black - Ground
Here's a link to my pictures:

Hope this helps,


21st February 2003, 12:46 AM
Thanks very much for your info and help, i finally installed it, I had it sitting around and decieded to install.