2005 Toyota RAV4 Is the electrical system 12V/24V DC Negative Ground system?

In modern automobiles' 12V systems the positive is an isolated system and the negative uses the vehicle's chassis as the conductor. Since DC voltage is a two wire system there is no such thing as a ground per se. Any grounding that would be required would be referencing the negative terminal anyway. So you could ground anywhere there is bare metal in the car.

all of this work when all you need is the correct LED units
bulbs work which ever way the polarity is and bulb holders (sockets are always positive to the enter with the ground being on the outside)
by reversing the polarity at the battery terminals , other items that require a positive feed only , like the ignition module , converter etc will burn out
Flashers work through a relay and by reversing the polarity the coil used to close the points will not work
Replace all of the units that you have damaged by reversing the polarity and just connect the led 's up as you would a normal bulb
All of the rest is from you very limited knowledge of electrics

1997 Toyota RAV4 Car Stereo Wiring Diagram
Car Radio Battery Constant 12v+ Wire: Blue/Yellow
Car Radio Accessory Switched 12v+ Wire: Gray
Car Radio Ground Wire: Brown
Car Radio Illumination Wire: Green/White
Left Front Speaker Positive Wire (+): Purple
Left Front Speaker Negative Wire (-): Violet
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Blue
Left Rear Speaker Positive Wire (+): Black
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Red
Right Rear Speaker Negative Wire (-): White

REVERSE YOUR LEADS AND TRY AGAIN

When you go pos to neg from one battery to the next it increases voltage, pos to pos just increases amperage. You would want to wire 2 in series, just imagine stacking batteries in a flash light, pos from one to neg on next. Remaining pos and neg are 12v now. Run both remaining pos to starter and ground both negs. your pushing a lot of amps with the batteries and doing 12v, and your charging system is 12v. If you do another series from there, you have to regulate the voltage when the starter kicks in...you risk burning every light and electric component...just like running 12v in 6v system... You can also use 4 12v batteries and run all pos to pos and all neg to neg and have mega cranking amps...that is how all modern big trucks are set up. Your pushing around 7k cranking amps that way(1500 per battery)...plenty to start the healthiest cat... And don't have the worry of dual voltages or running in series. You really don't need 24v to start and unless you have a 24v alternator, these are your 2 options. Best bet if your not sure is to try with 12v...no risk of frying anything even on 24v system. 24v on 12v system is, on the other hand, a big risk.

PYLE, 3.5 MONITOR INSTALLATION INSTRUCTIONS, INSTALLED IN SUV. As others have mentioned ThePyle Instructions are pretty much non-existant. As a formerly ASE Certified mechanic I am posting this to try to help others.THE PYLE KIT: Monitor + Camera Mount + Wiring Harness for hard wiring into vehicle electrical. --- Additional Materials Required to Install: 3ea. coils of automotive 18 ga. wire. One red, one black, and one white. 1/8" non insulated wire but connectors, wire shrink wrap (1/4", 3/16\', 5/16" AND 3/8" best to get assort. pack). Self taping sheet metal screws 1/2" long. Roll of electrical tape, Barbed Butt Connectors (2ea.- see illustration wiring Monitor posted this site). Rubber wire grommet 3/8" outside, 1/8" for wire, 1ea. req. Pull ties. --- Tools Required: Utility Knife, Drill w. phillips bit driver, wire tripper, volt meter, small pry bar. + Misc. ---

FIRST THING TO DO IS ALWAYS CHECK THE FUSES FOR THESE SYSTEMS AND THE RELAYS. TO TEST A RELAY GET A ELECTRICAL TESTER FOR A CAR, AND TURN IT TO 12v AND PLACE ONE LEAD ON ONE BLADE OF THE RELAY AND ONE ON THE OTHER BLADE, IF THE METER GOES UP THEN IT IS OK. SOME RELAYS HAVE MORE THEN ONE BLADE, ONE NEGATIVE, ONE POSITIVE AND GROUND. YOU WILL HAVE TO TRY ALL THREE, BUT IF THERE ARE THREE THE BLADE THAT IS THE OPPOSITE WAY THEN THE OTHER TWO IS USUALLY GROUND.

12V DC negative ground...for what reason?

In 12 volt DC automotive electrical systems black is always the ground wire or negative. Make sure you disconnect the battery before doing any electrical work (unhook the negative cable first). Don't splice into any wires under the dash, use a piggyback fuse connector on one of the accessory fuses eg; cigarette lighter.