Installation of a Tekonsha Primus IQ brake controller on Toyota FJ Cruiser 2007

Published 09/22/2014

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Adapter 4-Pole to 7-Pole and 4-Pole

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Tekonsha Primus IQ Trailer Brake Controller - Up to 3 Axles - Proportional

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$87.67

Question:

I recently purchased a Tkonsha Primus IQ brake controller and ETBC7 installation kit. The installation was easy but time consuming. With the exception of the final step #16 - Inside the cab, only one connection remains. Find the the wires connected to the brake stop light swithch at the top of the brake pedal. Using a circuit tester, test the wire to locate the wire that carries a signal only when the brake pedal is engaged. Using a Quick Splice Wire Connector, conect that wire to the brake controller red wire. Problem, there are multiple wires coming out of the switch. I did find one that was hot only when the brake pedal was depressed. It is a very small guage wire 16 or 18 gage and I would using the splicer on it along with a 12 gage wire from the controller. Will the differnece in size cause any issues making a good connection? Are you sure that splicing into that wire and using it as the signal to the brake controller will not damage the Toyota wiring circuits? Just dont want to damage the electrical system. I had purchased the OEM trailer 4 pin wiring harness and installed it a few weeks back. Is there anyway to splice into it for the brake controller? It used the factory installed wiring harness and I did not need to splice any factor wiring. Just concerned about splicing into the factor wiring. Any guidance would be apprciated. Thank you,

asked by: Richard

Expert Reply:

Sounds like you did find the correct wire to use for the stoplight switch for installing a brake controller on your 2007 Toyota FJ Cruiser. It can be difficult using a quick splice for a thicker gauge wire on a thinner wire like the 16 or 18 gauge wire on your vehicle. What you could do is strip back a section of the wire on the brake switch and then solder the connection. Soldering connections is often times the more recommended method anyway.

What I like to do to strip back thin wire is use a lighter to melt the insulation and then peal it off the wire. This way you don't run the risk of cutting an already thin wire. Once done you would want to cover the connection with electrical tape.

This won't affect your vehicle wiring either. This signal wire won't put any draw on your brake light circuits.

I attached a two part video series that shows this kit being installed on a 2008 FJ Cruiser like yours for more info.

expert reply by: Jameson C