Well I admit that I am too overworked, tired and lazy to search older posts or probe the fuse circuits but I'll ask anyway in case someone already has the answer on hand and or experience.

I'm adding a tekonsha primus brake controller to the 4runner, and the installation manual calls for a 20 or 30 amp fuse to power the brake controller.

I'll use 20 amp fuse, a mini atm ''add a fuse'' and hopefully piggyback into the interior fuses assortment under/left of the steering wheel. I have found a 16 awg one that should handle that kind of amp.

I would need a ''always on'' circuit since the brake controller needs current to keep its settings. Anyone has a suggestion on which fuse to tap in?

Always on..... [ Dome] light circuit

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I don't know about the Gen3 but the Gen4 has a connector in the left/driver's kick panel. It was tucked in there, just the wired connector and it fit my Tekonsha 3. I have the towing package, which probably makes a difference.

Brillo: problem there is the brake controller asks for 20 amps. I doubt that the dome circuit can handle unless it's paired with some other equipment, and there is certainly no dome light fuse in that compartment near your left knee.

and ArthurKotb; I am pretty sure the 3rd gen didn't have that, and also I've looked around in there just in case beforehand, and I have not found any trailer wiring connector unfortunately.

The cigar lighter, if you have one or if there is a place in the fuse box, should be a 20 amp fuse

Ah.. you maybe running a 12 gauage wire and making your own circuit.... You are correct you not pulling 20 amps off your dome..

I figured the memory was a microscopic drain like are clocks and radio memory.

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Thanks buddy, I didn't think of that. If there is no fuse, I'll tap directly into the lighter circuit.

Brillo, it's probably a few milliamps only for the memory for sure, but sending the power to the trailer brakes' magnets is where it must be drawing so much.

Thanks guys

Why not just run an appropriate sized wire from the battery to the controller? 20a is a decent draw, and if I remember correctly the cigarette plug has a sticker on it saying not to exceed 10a.

Dome circuit rated 15A, if reading print correctly only load is dome lights.
Don't see controller being too much for circuit. LED's in domes less circuit load way brighter.
Who has all dome lights on at one time for extended time.
01-02's have 25A towing circuit from battery at rear quarter vent.

Brake controller? Run a 10 gauge off the battery to the controller. Use a second 10 gauge for trailer charge connection (if going to 7 wire). Don't try to hack it - none of the interior circuits have enough current to spare for what you want to do.

-Charlie

@phattyduck

This is what I've used to wire up a Tekonsha brake controller on my 97 Tacoma, and Dad's ford van:
Just a moment...

Came with everything needed to wire up the controller, easy to read instructions and fast customer service for questions when I was installing on the Ford.
Price today is actually $10 lower than what I paid back in 2016

As already mentioned the 4th Gen t4r and most newer Toyota's with tow abilities come with the plug under the dash and a pigtail to wire to the controller. This is what I used on my T4r and the Sequoia. If your rig came with factory tow bar you might check to see if you have the existing plug to tie into. I don't see that it was listed in the online images I read while searching for "1999 4runner wiring diagram" I understand that the late 1gen Tacomas 01-03 picked this up and IIRC my brother's limited 01 had it. Maybe the 4Runner picked it up sooner? Either way the images/PDF files found with that search should help you if you still want to tap into the fuse box.

Boort.

True, I finally figured that out after looking better through it. Didn't want to drill yet another hole through my firewall (have already 2 holes there for two amps). Fortunately my brain finally put itself out of neutral and thought of my amp installation under my driver seat which is wired with 4 AWG, so I got my power. I'll run 10 AWG from there to the controller and then the controller manual calls for 14 gauge for 2 axles control. Thanks for the help everyone.

My 2004 came with the brake controller tucked into the driver's kick panel. Those wires are 14 AWG and I have a 2-axle Airstream travel trailer. with electric brakes. My controller is a Tekonsha Prodigy P2 and I've never had any problems with it, but there is no 'memory' that I'm aware of. There's a dial to set the amount of braking needed and an emergency lever to add more if needed. It's pretty simple and does the job just fine.

That's a good solution! I'd still run larger gauge wire to the connector at the back of the truck, but that's just me. (that's what I did, though I used a Redarc controller so all I have visible is a simple knob on the dash)

For those with 4th gen or newer trucks reading this... the 3rd gen has no provisions for brake controllers from the factory. If it had the tow package, it was port/dealer installed with a plug-n-play style 4-pin harness in the back, nothing more. 01/02 got a factory installed 4-pin harness, but that's it. Nothing under the dash for brake controllers. 500lbs/5klbs tow rating with no extra rating with weight distribution.

-Charlie

just tried it yesterday with installation as told above. 10 AWG to the controller and 14 AWG to the back as per instruction. Working very well. Also installed a transmission cooler to keep that old 4 speed from overheating.

I really love the tekonsha primus, it's my second one, using the other on the jeep. It's relatively cheap, looks good, simple to operate and effective with the accelerometer built-in and the boost functions.