Relay Wiring harness for auxiliary lights and more

I’m a self professed penny pincher. I don’t like spending more money than I have to especially if I think I can DIY a solution. @crashnburn80 has several ongoing threads dedicated to upgraded halogen lighting for 2nd and 3rd gen tacos, and one of the parts frequently mentioned is an upgraded wiring harness. There’s no plug and play solutions for 3rd gens yet, so since I’m adding fogs and auxiliary high beams (Hella 700FF’s with 100w bulbs) to my SR I’ve decided to try out a Amazon parts experiment.

MICTuning makes a 12 gauge wiring harness for adding two light bars or other high powered lights to the truck for $20.

MICTUNING HD+ 12 Gauge 600W LED Light Bar Wiring Harness Kit w/ 60Amp Relay, 3 Free Fuse, Rocker Switch Blue(2 Lead)

$19 MICTUNING HD+ 12 Gauge LED Light Bar Wiring Harness Kit with 60Amp Relay, 3 Free Fuse, Rocker Switch Blue(2 Lead)

https://www.amazon.com/dp/B06WVWH5W4/ref=cm_sw_r_cp_api_i_ySOKCbP6QXQZ8

So I purchased on with the intention of using it for the Hellas, but I wanted to use it switched solely off of the stock high beams and not use the included rocker switch.

Here’s the harness out of the package


I disconnected the switch wiring and was left with these three wires. Blue should be switched positive, black ground, and white is a constant 12v from the battery and what needs to be removed.


Time to open things up:




I used a small Allen wrench to pop the terminals out



clipped the white wire, then I wrapped the negatives and the clipped white end in electrical tape and reassembled.





Now I just need to order an H9 pigtail so I can make a splitter to trigger the lights and get things wired up. To be continued...

 

are those black wires only held on by the wire jacket crimp?

 

I have my big 7" spot lights hooked up to my high beams as well. However in think the extra overide switch is important. When getting a inspection or if pulled over by a cop I have it turned off because those lights are for offroad use only.

 

I believe they are soldered as well, it's a tight connection.

As far as inspections, it's not a problem in Alaska.

 

Nice! That’s how I would set it up as well.

A common failure on those inexpensive harnesses are the Chinese relay. You might consider preemptively swapping to a high quality European Bosch unit. Double check prong orientation for fitment:

Bosch 332019150 Relay

$9 Bosch 332019150 Relay

https://www.amazon.com/dp/B0010ADJIE/ref=cm_sw_r_cp_api_i_r79KCbX34N35G

Hella bulbs can vary quite a bit in quality depending on who makes them, since Hella doesn’t manufacture their own bulbs. For the 100w H3s used by the 700FF I’d look at German made Osrams or Narvas when your up for replacement.

 

Success!



It took some more trimming but it all went together pretty seamlessly. There was just enough wire on the first lead to run the wires and connectors inside of the hella housing. I ended up using a positap to connect the blue signal wire on the high beam positive wire to trigger the relay.

 

I just bought a harness from mictuning to power a small led pod to light the bed of my truck. I'll see how long it lasts, but so far in all of two weeks, no issues. Time will tell

Probably overthinking, but why would they add a connector between the switch and the relay? Seems like to me that's just a point of possible of failure. Do you think there could be any issues of removing the connector and just soldering the wires together? Thanks!

 

Yes you can.
The point of the switch is so you can control when they are on or off. The relay is so it can't be left of when truck is off.

 

Cool thanks. I just dont understand why they would add this connector. Seems like a waste of time and money.

 

Because people like connectors. Most people are not capable of making a clean connection that lasts.

 

Cool thanks! I guess I can add this to the things to do on the truck list. I would rather have a direct connection instead of having that connector.

 

The connector seemed silly to me as well, but I think it’s to allow the manufacturer to supply different switches easily. There’s several different options on Amazon for the same harness. However the way it’s wired I believe that if you use the supplied switch and harness the light for the switch will always be on causing the battery to drain. Better to remove it altogether imo, but again I didn’t want, need, or care to be able to switch the lights on independently of my high beams.

I’ll probably order the replacement relay eventually, just to have a spare.

Regarding bulb performance, I did not measure the stock 55w H3 bulb that came with the lights but I did measure the 100w vs the stock low and stock high beams. Using a lux meter on my phone at 16’, which is as far back as I could get in the warehouse, taking several measurements at the respective hot spots:

Low beam, stock bulb 270 lux
High beam, stock bulb 360 lux
Hella H3 100w bulb, 480 lux

The left Hella 700 is covered in this photo, both high beams are on.

 

Another benefit of the switch is legal. All these lights are for offroad use only. When I go in for my inspection it is turned off. There are some times I might want just the highs without the blinding amount of light.

The little red light bn is only on when the big lights are on. That is the point of a relay. It kills all power to the circuit when the switched wire is off.