I'm not sure if this is the same but the ground wire going to the stereo is not really ground! Try running the hot wires for your new stereo right to the fuse box or straight to the bat and see if that cures it. I had a problem that was very similar but it wasn't a Tacoma.
I suspect the switch is bad.
How do I change the dimmer switch on my 1993 corvette?
help mower!
how to change dimmer switch on 1997 Honda accord
To change a light switch to a dimmer, first turn off the power to the switch at the circuit breaker. Remove the existing switch and disconnect the wires. Connect the wires to the dimmer switch according to the manufacturer's instructions. Install the dimmer switch into the wall box and secure it in place. Turn the power back on and test the dimmer to ensure it is working properly.
a dimmer
A beam of light becoming dimmer is a physical change since it is reversible. Recharging its source will make the light beam bright again.
Usually a switch will only let you choose between ON and OFF, but a dimmer switch will let you change between Brighter or Darker.
A "dimmer" switch will change the brightness of lights.
To change a light switch to a dimmer switch, first turn off the power to the switch at the circuit breaker. Remove the existing switch cover and switch. Disconnect the wires from the old switch and connect them to the dimmer switch according to the manufacturer's instructions. Install the dimmer switch into the electrical box and secure it in place. Finally, replace the switch cover and turn the power back on to test the dimmer switch.
To change a dimmer switch to a regular switch, you will need to turn off the power to the switch at the circuit breaker, remove the dimmer switch, and install a regular switch in its place. Make sure to follow proper safety precautions and consult a professional if needed.
To change a regular light switch to a dimmer switch, you will need to turn off the power to the switch at the circuit breaker, remove the existing switch, install the dimmer switch according to the manufacturer's instructions, and then turn the power back on to test the dimmer switch. It is important to follow all safety precautions and consult a professional if needed.