A/F Gauge install

[xk49]

I have an AutoMeter AF guage I'm installing, but I'm a little confused with some of the wiring. There are three "hot" wires illustrated in the diagram, but I can't understand why in the world there would be three. It's asking for the following:

12v Ignition (red)
12v Dash Lighting(white wire)
12v Direct to Battery(brown)

The white and red make sense, but the brown has me stumped. There's a toggle switch in the diagram between the battery and gauge for the brown wire. Under the toggle switch it says optional. Not sure if they are referring to the switch of the wire?

In the description for the brown wire it says, "Heater Overide for applications that provide less than 12.5 volts with engine running".

Electronics if by far my weakest point, so bear with me as I'll probably have some more questions flooding through.

[CamaroCracka]

without looking at it, it sounds like there is a relay in place. The brown wire provides the power to system. Installing an arming switch is optional so you don't always have to have the gauge on (probably extends sensor life). When the red wire gets power from the ignition circuit, it closes the relay completing brown wires power circuit. The system probably pulls too much current to safely place the brown wire on the ingnition circuit. The white wire just makes the light come on so any circuit that in only on when the key is turned will do. Hope that helps.

[1KillerSS]

Thats normal for a gauge, you have power that's on all the time, then switched for ignition, then night time lighting. You dont have to wire in the white wire on some gauges.

[Camaro_Custom_Painted]

You only need the brown wire if the red wire power is not connected to an adequate power source, that is, one that cannot supply the required voltage. If you are going into the fuse box (with the red wire) for power then you can simply ignore the brown one. The white wire, for lighting, should be tied into your dash lighting so that its dimmable. I can tell you the wire to tap for that once I get home and look at my files. PM me if you want to know.

[1KillerSS]

This from Autometer's website, in the instructions section.

Brown Wire(Optional Peak/Recall & Warning WOT Switch):
Connect to Wide Open Throttle Switch. Required for
Peak Recall Functionality.

[1KillerSS]

Originally Posted by 1KillerSS

This from Autometer's website, in the instructions section.

Brown Wire(Optional Peak/Recall & Warning WOT Switch):
Connect to Wide Open Throttle Switch. Required for
Peak Recall Functionality.

Sorry, I don't think that is applicable for your model number. That's for another one of their gauges. This one is for you.

Brown Wire (Heater Override):
Connect to a normally open switch. Connect the
other switch terminal to battery positive (+).