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Discussion Starter #1
anybody know backup light pin out for an 03?

Hi everybody, I am trying to tap directly into the wire harness that runs into the tail light provide power for my backup camera. It has 5 wire.

So I turned on my car and put it in reverse... and check it with a multimeter... So I figure out that the red wire is the pos for the backup light. Now... the interesting thing is that the rest of the wire seem to be grounded when the other light are off and seem to be switched on depend on what light is on. So now my concern is that which wire is really the ground for the back up light.

I don't know if I am making any sense but it seem like the whole vehicle is grounded together when it's turn off... and depend on whatever got switch on then that wire become "live" but as soon as it's off the wire seem to be grounded. If anybody can shred any light into this I would really appreciate it.
 

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Toyotas are wired with switched grounds instead of switched power. Power is run to the accessory and the return loop to ground contains the switch.
 

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Discussion Starter #3
A10GAC, Thanks for reply... I am still confuse of how every wire is grounded when it's off and become live when it's switched on.

If I understand your explaination right then I should be able to detect a live current leading to the accessory when it's off... instead everything seem to be grounded when it's off including the hot wire.
 

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You will only be able to detect voltage at the accessory when it's off, since the accessory is off and not drawing any power there will be no current. In a switched ground system there will always be power at the accessory but since there is no path to ground until the switch closes the accessory will remain off.

Without knowing how you are hooking up the meter I can only speculate that you are either 1) reading a ground through another component in the system or 2) completing the circuit through the meter and getting a false reading. If you remove one of the back up light bulbs and leave the truck in park (or 1st gear if it's a standard) you should be able to meter from the socket to the chassis ground. One terminal should be a short to ground and the other should read open. According to the Haynes manual I have the backup circuit from 1996-2000 Toyota 4Runners used a Red/Black power lead and a White/Black ground lead. No telling if Toyota is still using the same color codes in 2003.

Hope this helps.
 

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Discussion Starter #5
Interesting... I on the other hand I detect no voltage what so ever when everything is off... Here is how I got my meter set up...

With the wire harness disconnected and everything off.

First I set my meter to check for voltage. I checked the 5 pin against a good ground (the car body) and got 0 voltage across the 5 wire.
I then set the meter to check for continuity... interesting thing I found that the 5 pin and the ground is connected...

Now with the key on and the car in reverse.

I found the meter report 12 v for one of the pin (the red wire) and the car body. Now the interesting thing is that I also got 12 v on the meter when I checked this pin against all the other pin.

Now I turn on the light... and one of the other pin (let call it pin 2) become hot and this pin 2 also report 12 v against the body of the car or against the other pin...

Any thought?
 

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At this point you might want to drop by the local Barnes & Noble or auto parts store and see if they have a Haynes or Chilton manual for your vehicle. Both will include a circuit diagram with color codes for the lighting system. Just having them for the torque value list is worth the $20-25.

Best of luck with the camera system, post and let us know how it works out.
 

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Discussion Starter #7
I did look for Haynes or Chilton manual at Pepboy and on the net for my 2003 4Runner but I couldn't find any... I think the latest they got was 02 which is the 3 third gen. Anyway I have decided to tap into the accessory power in the back and use the backup wire to switch on the relay. I probably will do this on Wed or so... So I'll be back to let you guy know how it all goes. Thanks for the help again.
 
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