Installing a brake controller and hotwire

[sandshoe]

As promised, here is a description of how I went about installing a brake controller and 12V hotwire in my ZR6.

Brake controller:

I used a Tekonsha P3 (generally considered to be one of the best currently available). I used 4 square mm wire (not to be confused with 4 mm wire) for the connection, with a 30A self-resetting circuit breaker

Hotwire:

I used 6B&S cable (13 square mm) for this. I have seen recommendations ranging from 6 square mm to 3B&S, with the rule of thumb seeming to be to use the largest cable that you can fit into the vehicle. For me, that was 6B&S. I used a maxi-fuse holder with a 40A fuse. I also used a 100A solenoid (the sort used for dual battery set-ups in big 4WDs) to interrupt the power when the car ignition was off. Any caravanner will be only too well aware of what happens if you leave a 12V fridge running when the engine is switched off!

The following link was very useful:

http://www.spokanister.net/Docs/RAV4_Trail...ire_Harness.pdf

It is Toyota's installation instructions for their towbar wiring package, and details how to remove the trim panels. (Actually, I found that I didn't need the nylon trim removal tool that they talk about - firm pressure with fingers was enough to release the panels, with no risk of scratching anything.

Step-by-step:

I started in the passenger footwell, removing the trim. High up on the left side of the firewall is a large bundle of cables passing through a large grommet. Built into this grommet is a sort of nipple, projecting forward into the engine bay. I don't know what this is for, but it was perfect for me to get my wires through. If you reach behind the left side shocker mount from under the bonnet you can feel the end of this nipple thing. Using a small mirror I was able to snip the end off.

By taping the cables together to a guide wire and applying a bit of liquid soap I was able to pull them through from the footwell into the engine bay.

The engine bay connections are straightforward. I ziplocked the 30A CB to the cable next to the battery mount, and put the hotwire fuse in the space next to the air filter cover.

Mounting the P3:

This was tricky. In other cars I have had the brake controller under the dash near my left knee, but in the RAV there just isn't the room. Also, there is a knee airbag under there, and I certainly didn't want to mess around with that.

I ended up putting it in the storage compartment between the cigarette lighter and the A/C controls. I had some guidance from this link:

http://toyotaownersclub.com/forums/index.php?showtopic=77298

It is about handbrake adjustments, but it shows how to remove some of the console trim. The working space is tiny, and screwing in the pocket mount was very difficult due to limited access, but it is possible! I had to drill the pilot holes for the mounting screws by twirling a 3/32 bit between my fingers! You also need an access hole in the back of the compartment (there is about 1cm clearance behind!)

Despite all this I was pleased with the result: The P3 matches the other fittings very nicely, and you can even set the display colour to orange to match the other displays!

The brake controller has four wires: (1) positive, to connect direct to the battery via the CB; (2) negative also back to the battery; (3) a blue wire which has to run the length of the car and connect to the "service brake" terminal of the trailer connector. (4) The other wire (red) has to splice into the brake light circuit. Many people do this by connecting to the stop light switch above the brake pedal, but I didn't want to go near the airbag, so I ran this wire down the car with the others. Anyway, I've done it like this before!

All these wires fit in next to the others wires heading that way. It's a bit of a squeeze, but they fit.

In the rear compartment, the whole left side trim needs to be removed.

Brake controller connections:

Trace the corrugated conduit back from the trailer socket to where it plugs into the control box. Here I found the blue wire from the trailer socket hanging in mid air - I gather that they never connect this. I connected the blue wire from the brake controller here.

Next I carefully cut into the corrugated conduit and found the red brake light wire. I used a Scotch-lock connector to splice the red wire from the brake controller in here.

That's the brake controller done!

Hot wire connections:

Just below the seatbelt reel there is an earth point. I interrupted the negative cable here, connected it to this point, then continued it on.

I located the solenoid switch in the space where the tool kit goes. The heavy positive battery cable connects to one of the switched terminals, then goes on from the other.

One of the smaller solenoid terminals connects to the earth point. The other small terminal connects to the 12V wire feeding the power socket in the left rear compartment. This wire is white with a black stripe, and is switched with the ignition. I connected this wire to the solenoid, then reconnected the downstream end to the cold side of the solenoid switch terminal.

The two heavy cables then go outside the car and run with the trailer socket wires to an Anderson plug.

I used a quite a bit of split conduit, electrical tape, and ziplocks to tidy it all up.

Here's a few pictures:

This is the left hand rear compartment, where the tool kit goes. The solenoid switch is at the bottom. Cable 1 is the two brake controller wires which connect to the towbar wiring loom. Wire 2 is a 12V wire feeding to the "aux" pin of the trailer socket from the hot side of the solenoid switch. Wire 3 is 12V from the accessory socket to the solenoid. Wire 4 goes to earth (I ran out of black wire!) You can see the main 12V hot wire on each side of the switch. The heavy earth cable isn't in this picture.

Under the bonnet:

1 is the 12V connection. The fat wire is the hotwire; the thinner wire is to the brake controller.

2 is the 30A circuit breaker for the BC circuit.

3 is the negative connection - again, one fat for the hotwire and one thinner for the BC.

4 is a maxi blade fuse holder for the hotwire.

This is the 7-pin flat trailer socket below and the 50A Anderson plug above.

The brake controller mounted in the front pocket.

Let me know if I haven't been clear, or if you'd like more detail.

[mmm]

Sandshoe,

Very good description and detailed. I will have a good read when I get a chance. You should go into buisiness. I will be looking at doing the same down the track. Don't suppose you are close to Newcaslte???

Cheers MMM

[sandshoe]

Sorry, MMM. I'm in Adelaide!

You're welcome to any help I can give over the net, of course.

[mmm]

Cheers Sandshoe