T7 Towing Brake T harness info

For those who don't tow as much and for those who do. Tap for a "hot" 40A fuse (add a fuse holder for your toys), acc illumination and a ground.

Didya @tonered ?

 

That looks like it. Good power.

 

Since this thread is so tight, should be perhaps add links to "places to buy"?

Extreme Terrain
Parts Geek

$29 Tekonsha Trailer Brake Controller Harness, Compatible with Select Toyota Tacoma, Tundra

Amazon
Auto Anything

Any others?

 

Oh and it looks like most of these aren't fully pinned? I thought I read somewhere that this plug also has dash illumination? Would be sweet to get one harness which can light switches _and_ tap aux power. Still hunting for something like that but not totally sure the factory connector supplies all of the pins?

 

Sure. For me though, I just jammed a spade in there. It has worked beautifully.

 

Oh, a DIY harness with spades jammed in, I could do that, sounds like a good option if it doesn't fall out...

 

It has been great for a long time. With it behind the kick panel, no unintentional problems.

 

Most Electronic Brake Modules don't use the Illumination Circuit, but the vehicle side has it. It uses a 090/2.3II terminal. Look at first post.

Vehicle Side...

 

Yeah, I'm hunting for something I can buy which would be pinned there b/c I am trying (and it seems like I'm losing) to avoid buying a crimper and proper terminals...

So Power, Ground, Brake, Tail, Stop, one of those is illumination? The green one marked tail? I assumed it was for taillights, brake for brake lights, but then I wasn't sure what's different between brake and stop unless stop is for controlling the force to apply to the trailer brake?

 

Oh man. I just did that for my Viair project. Freaking satisfying to have the proper tools. Just get 'em!

https://www.tacomaworld.com/threads/viair-automatic-mod-vam.680478/

Honestly, they have me thinking about re-crimping this power tap just for the fun it.

 

Tail is same as Parking. If you connect the negative of an added switch to the beige, it'll dim. If not, then it will just illuminate with "regular" ground.

Stop is the input to the Break Controller.

 

Ah, I get it now, trailer harness has undimmed illumination via (+) lead for parking lights. What it doesn’t have is dimmer ground (-) to complete the circuit for dimmed switch illumination. And the beige wire for that is a TBD for me. Makes sense now.

Since this is 40amp max, what would the relay recommendation be? I could get an 80 amp relay for a safety margin or a 20/30 or a 30/40. I assume I ought to go with the 80 to be safe but not sure if brand matters in terms of quality?

So it mostly boils down to a question of mounting locations for relay and fuse block.

With all that said, I am planning on bringing in 4 gauge from the battery for my amplifiers to under the seat so if I were to ignore illumination then I’m not sure the trailer harness buys me all that much extra. Perhaps the biggest reason to use it is that the wire size is already good for a connector to the relay vs a distribution block to reduce the 4 gauge to 12 or 14.

 

Just to close out the loop on this if anyone else stumbles on it in the future. Caribe Makaira redirected me to an earlier post on my build thread where he had spelled this out for me. I'm nearly complete and have tested and confirmed all works properly.

Specifics as follows:

1. I purchased a Tekonsha brake controller harness. I noticed it had blue and black colors reversed and I wanted a clean setup for this work so I de-pinned everything and re-pinned the blue to match OEM blue so it'd all be blue and removed all other wires from the connector.
2. Purchased 25' of blue 12 gauge GLX wire to extend to under the cupholders.
3. Purchased a blue sea maxi fuse holder to install in the driver's kick panel and a blue sea compact 8 circuit fuse block for under the cupholders.
4. Purchased a Tyco high current relay model 23232 A 0001 X003 to turn brake controller +12V to ignition switched (75amp max)
5. Recycled the leads from POUTLET2 which fed the center console 12v power connector after removing them from the plastic connector to trigger the relay
6. Various heat shrink, loom, fuses and two sizes of ring terminals, using the obvious ground, mounted the fuse holders and relay, test fit.

Using a maxi fuse holder in the driver's kick gives me maximum flexibility if, in the future, I need to add a brake controller. I can simply run a new 12 gauge (or 10) lead from the battery directly via one of the firewall grommets without disruption to the downstream components. It also allows me to join the rather short brake controller harness wire to the longer wire needed to reach the destination location without soldering or crimping and burying that joint inside the dash. So, it's strategic for me but entirely not necessary for anyone else as this circuit already has a fuse upstream.

NOTE: It is possible to re-pin and tap into the light circuit for power to switches but the Tekonsha doesn't have a lead pinned for that by default. Since I wasn't going to use that harness for actual brake controller duty, the red wire would have worked well for this. I'm planning to tap illumination from the A pillar harness instead so I can get dimmed illumination, leveraging a DSIM T harness for that.

Photo is prior to final wire routing and zip ties, also I'm still waiting on some ring crimp connectors and that blue GLX wire to complete this.

 

Not a location I'd choose but...

 

Where would you want this stuff? Somewhere where the fuses would be more accessible? Or somewhere less prone to accidental short?

Thanks for the suggestion on insulating, I wonder how best to do that with this relay and still allow disassembly without cutting. Seems like a slide-on boot would be best.

 

Boot would be great, tight.
Location would've been near the other fuse panel in the cab..Driver Kick panel.

 

I'm planning to use this as power for a heated seat install. I had to repin the plug. Does this look right? Black is ground, blue is power and white is illumination for the switches?

The power and illumination will be run through a simple fuse box for a clean install. Should also leave me an extra constant 12v source (each seat will have it's own fuse and one for illumination). I plan to grab a switch 12V from the fuse panel. https://www.dormanproducts.com/p-16556-85668.aspx

 

So, on my Tekonsha, blue and black were reversed vs the colors Caribe used in his diagram. I'm not sure if mine was a one-off goof though.

The black is not ground. Ground is pin 5 and on the Tekonsha it was white with an extra ring terminal. If yours was a Tekonsha too and you've re-pinned and swapped blue and black then it looks like you are set on +12v and parking lights but the black wire in pin 7 is not ground and you want to either de-pin or tape/heat shrink it off. Since it looks like you've already shuffled I would de-pin.

The ground from the factory harness is tiny and not worth tapping into IMHO, better to use a ring terminal to vehicle chassis than go through the connector to what looks like 22 gauge or at best 20 gauge.

 

Ah, thanks. I see that now looking at the first post (what I get for "working" and doing this at the same time). I just looked a the bottom pic and saw both 5 & 7 as black and thought both were ground. I went with 7 for exactly what you're saying. 5 wiring gauge was too thin for my liking. I removed pin 7 and will use 8 for power and 3 for lights. I'll ground to the chassis.

Too bad there's no switched 12v on here.

 

Agreed would be nice to have switched power too.

I have an extra high current relay which I'm not sure I'm going to use quite yet but I _might_ try to use it for switched power in the bed down the road.

I think the only useful pins in this connector for aux switches/fuses are +12v and parking lights. I was actually working on my heated seat switches last night/this morning and I'm pretty close to adding the parking light tap for them, should have just done that up front.