I had an aftermarket radio with GPS installed in my SUV 2 years ago, since that time I have replaced the battery 4 times, I have also had the truck in the Toyota dealership for an electrical diagnostic, they found no problems other than this, quoted from the dealership diagnostic test, " let electrical system go to rest, noticed consistent voltage draw, began removing fuses, when radio fuse removed draw stopped. Unplugged radio, let it sit over night only lost .04 volts with radio unplugged, next day plugged radio back in with center stack trim still removed from access. Found over 3 hour span voltage dropped.3 volts. Recommend replacement of radio. However radio store says there is nothing wrong with radio. Any suggestions or ideas on this matter.

  • Welcome to Motor Vehicle Maintenance & Repair! I'd suggest either replace the radio, or put the radio on a separate battery which is isolated from the main battery. That seems like a fairly serious power draw, though they don't mention the amperage which is getting used. Sep 28, 2018 at 21:22
  • What is the model of the radio? It might be wired incorrectly causing it to use more power all the time because it thinks the car is on the whole time not realizing it is running off the battery. There may also be settings that control it's behavior when the vehicle is off such as trying to keep an active GPS lock. Turning that off would reduce the power consumption but make it take a little longer to figure out your location when you start the vehicle. Sep 28, 2018 at 21:27

1 Answer 1


You have your 12 Volts of power hooked up, but the ignition wire is loose somewhere, recheck your wiring schematic, it should look something like this

When your ignition is turned to the off position, there should be no signals sent for power


12V Constant power/memory - blue/yellow

Power antenna - black/red - pink/blue

Factory amp turn on - pink/blue

Ignition 12V (key on) - gray

Illumination - green wire

Ground - Brown wire

Left front speaker (+) - pink
Left front speaker (-) - violet

Right front speaker (+) - light green
Right front speaker (-) - blue

Left rear speaker (+) - black
Left rear speaker (-) - yellow

Right rear speaker (+) - red
Right rear speaker (-) - white


12V Constant power/memory - yellow

Factory amp turn on - blue/white

Ignition 12V (key on) - red

Power antenna - blue

Ground - Black wire

Illumination - orange

Left front speaker (+) - white
Left front speaker (-) - white/black

Right front speaker (+) - gray
Right front speaker (-) - gray/black

Left rear speaker (+) - green
Left rear speaker (-) - green/black

Right rear speaker (+) - purple
Right rear speaker (-) - purple/black

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