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AEM Air/Fuel gauge wiring issue

28 April 2011
Santa Fe, NM
(this is also posted in forced induction, but I think it belongs here.)

I have an AEM air/fuel gauge wired to my cigarette lighter power and ground. This creates a VERY annoying high pitch coming from my speakers. When the radio is off, or the the wires are unplugged the sound is gone.

There is only a red and a black wire to hook up.

My question is where else can I connect the wires to power the gauge?

The instructions read:

Connect to a switched 10-18 volt power source utilizing a 10A fuse.

For those using a gauge, where do you have yours hooked up?


Finding a better ground point is the first thing I'd do. Don't cheap out on the wires either. Use at least the same gauge or thicker. It's probably a 16gauge or thicker.

If that still doesn't solve it then run the both +/- wire directly to the batt terminal even outside the car just to test with. See if that still makes noise. If not then you know it's a wiring issue.
RYU is right, find a better ground. The lighter gets it's ground from the under dash fuse box and that's probably where the sound is being induced. You can try wiring the 12v lead to the top of the fuse box but hook up to chassis ground somewhere.

I ran both red and black directly from battery. Then pink wire to ign switch from cig