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Just finished the rather long task of disassembling the drivers side interior panels and installing the wiring harness. I don't need trailer brakes or a trailer battery charging circuit right now, but I want to run the wires before I put all the panels back in.

Anyone know what gauge of wire I should use for trailer brakes and battery charging?

Thanks,
Craig

P.S. Thanks to all who have posted their experiences with installing the wiring harness - they all helped. That was a really "fun" task, especially pulling the first panel loose!
 

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I ran 10ga (black) for the battery charging circuit. 12 ga is big enough to carry the current but the voltage drop is less with 10ga resulting in a more complete charge on the trailer battery.

I ran 12 ga (blue) for the electric trailer brakes. 14 ga is generally used for single axle brakes and 12 gauge is used for 2 axles. My trailer only has a single axle but the cost difference is slight and it leaves my options open for the future.

Be sure to run a 10ga (white) ground wire as well. I ran mine from the factory ground screw behind the left rear interior side panel. This is the same screw that the factory harness uses for the ground connection.
 
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Thanks! I'll pick some wire up tomorrow and put my RAV back together.

P.S. I had guessed that you, Harold, would be the one to give me an answer :) You seem to have answered lots of peoples questions - we all appreciate it!
 

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Harold said:
I ran 10ga (black) for the battery charging circuit. 12 ga is big enough to carry the current but the voltage drop is less with 10ga resulting in a more complete charge on the trailer battery.

I ran 12 ga (blue) for the electric trailer brakes. 14 ga is generally used for single axle brakes and 12 gauge is used for 2 axles. My trailer only has a single axle but the cost difference is slight and it leaves my options open for the future.

Be sure to run a 10ga (white) ground wire as well. I ran mine from the factory ground screw behind the left rear interior side panel. This is the same screw that the factory harness uses for the ground connection.
I'm thinking about having Toyota install the OEM wiring harness. I'm wondering if I can ask them to pull extra wires at the same time while the panels are off. Just so I'm clear, there are only three wires needed? Each of the two circuits use the same 10 ga white ground?

Do you know the approximate lengths of the 12 ga (blue), 10 ga (black) and 10 ga (white) ground wires I would need to get?

I'm assuming if they pull the wires they are going from the battery to the rear left panel. Is that right? Where would the controller be mounted?
 

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I think 12 AWG is fine for battery charge (the length is short enough that the voltage drop isn't that significant), and it has the advantage that you can "just" fit two 12 AWG wires side by side into a 1/4 inch split loom. If you go with a bigger gage you will have to use 3/8 inch loom and it's a little harder to route through the vehicle.

One problem with this large gage is finding long enough lengths at the auto store - typically they are 16 ft in this size. Buy off the bulk rolls at NAPA and you can get 25 feet of each and have enough to not run out 6 inches short of your destination!

Seems like more folks are starting to install controllers. There are a couple of other threads around.

Check here for some ideas

http://www.spokanister.net/Vehicles_RAV4_Brake_control.html

Good luck... it's a big job.
 

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John E Davies said:
I think 12 AWG is fine for battery charge (the length is short enough that the voltage drop isn't that significant), and it has the advantage that you can "just" fit two 12 AWG wires side by side into a 1/4 inch split loom. If you go with a bigger gage you will have to use 3/8 inch loom and it's a little harder to route through the vehicle.

One problem with this large gage is finding long enough lengths at the auto store - typically they are 16 ft in this size. Buy off the bulk rolls at NAPA and you can get 25 feet of each and have enough to not run out 6 inches short of your destination!

Seems like more folks are starting to install controllers. There are a couple of other threads around.

Check here for some ideas

http://www.spokanister.net/Vehicles_RAV4_Brake_control.html

Good luck... it's a big job.
When looking at the Techonsha P3 there is a Toyota OEM connector. Where does this connector connect to the Toyota harness? It is where you spliced the brake wire near the bottom of your instructions?
 

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bluenoser613 said:
When looking at the Techonsha P3 there is a Toyota OEM connector. Where does this connector connect to the Toyota harness? It is where you spliced the brake wire near the bottom of your instructions?
That one is for the trucks only (Tacoma/ Tundra, maybe 4Runner etc). The Tekonsha lady I talked to assured me it would work on my '07 Ltd: "Just plug it in under the dash." That made me feel really good until I actually looked under there. There is NO socket under the RAV4 dash for any aftermarket (or OEM) brake controller harness.

I really wonder about those engineers at Toyota sometimes: "So sorry... must use trailer brakes if over 600 pounds, but must figure out controller yourself."

Rant over.

Bottom line: you must string heavy gage wires all over the trucklet and make some splices to get the controller to work. There is, however, a cute connector on the front (hidden) side of the controller.
 

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John E Davies said:
bluenoser613 said:
When looking at the Techonsha P3 there is a Toyota OEM connector. Where does this connector connect to the Toyota harness? It is where you spliced the brake wire near the bottom of your instructions?
That one is for the trucks only (Tacoma/ Tundra, maybe 4Runner etc). The Tekonsha lady I talked to assured me it would work on my '07 Ltd: "Just plug it in under the dash." That made me feel really good until I actually looked under there. There is NO socket under the RAV4 dash for any aftermarket (or OEM) brake controller harness.
Hmmm... I wonder if there is a market for a 7 wire harness, or if there is a 7 wire alternate harness that would work.
 

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Harold said:
I ran 10ga (black) for the battery charging circuit. 12 ga is big enough to carry the current but the voltage drop is less with 10ga resulting in a more complete charge on the trailer battery.

I ran 12 ga (blue) for the electric trailer brakes. 14 ga is generally used for single axle brakes and 12 gauge is used for 2 axles. My trailer only has a single axle but the cost difference is slight and it leaves my options open for the future.

Be sure to run a 10ga (white) ground wire as well. I ran mine from the factory ground screw behind the left rear interior side panel. This is the same screw that the factory harness uses for the ground connection.
Can I use the 12V from the accessory plug near the left cargo door for the battery charging circuit instead of running another wire from the battery?
 

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bluenoser613 said:
Can I use the 12V from the accessory plug near the left cargo door for the battery charging circuit instead of running another wire from the battery?
Nope... the Toyota wires are way, WAY too small for the electrical load. That socket is fine for a light load like a portable cooler or laptop charger.

You have to run a dedicated heavy wire all the way to the front for battery charging...
 
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