Solved! Car Audio Issue - Pioneer DEH-S31BT

May 19, 2020
I installed the Pioneer DEH-S31BT CD receiver into a 2006 Ford Focus SE. I used the proper harness, etc., and the radio operates fine except that it loses it's memory (Date, Time, Presets, EQ Settings, etc.) when I turn the ignition off. Originally, it had an in-dash 6 CD Changer in it. The car battery is fully charged. The only thing I can think of is that I used the ground on the harness instead of straight to the chassis of the car. Could the car ignition be cutting off the ground? I double checked the wire diagram from the harness manufacturer and from Pioneer. There is nothing listed for radio memory on the wiring harness diagram from Pioneer. I used every wire on the radio's harness to the car harness I purchased except the blue one for the power antenna/amplifier PW Switch. The old radio had an additional connector for the 6 CD changer that is unused. I figured the other small harness was just because it was a 6 CD changer and that maybe it needed additional power? The 6 CD changer is stock in the 2006 Ford Focus. It seems as though when the ignition is off, it is cutting all power to the radio.


Both red and yellow are 12v. Red is 12v from the ignition so the deck turns on with the key and the yellow is the constant 12v(from battery) to keep memory and the clock from resetting. If they are reversed that's likely the problem.
May 19, 2020
Sounds like the 12v constant(usually yellow) is not hooked up or has a bad connection.
Well, I did solder them together. However, I think I figured out the issue. I think I misinterpreted Pioneer's directions and had the yellow and red wires flipped between the harnesses. The pioneer's directions has the Yellow as 12volt and the Car harness end had the Red as 12volt. So I thought that maybe they were reversed between the car harness and stereo. So I wired the Yellow to Red instead of Yellow to Yellow and Red to Red. I'll have pull everything out and un-solder then re-solder them again. Thanks for the nudge in the right direction.

Sonic Illusions

Feb 16, 2019
Sounds solved! BTW... the ignition doesn't shut off ground. Everything is connected to "COMMON CHASSIS GROUND" in a car. It's called common because the battery and all electronics, including the engine block, refer to NEG COMM GND and are connected to the chassis in some way. Electrical current flows from - to +, so that's why in high-current car audio installations, the negative chassis ground must be as heavy gauge conductor as the positive, collectively.
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