Selectable quad wiring; with diagrams & example pics

[satrya]

If you have space for 2 pairs of HID projectors, and want to be able to use each pair on demand, this is an example of how it can be done. I did this for my 2nd bugeye retrofit, but didn't have much detail in the build thread.

What do you need:

• Two sets of HID set (harness, ballasts, projectors, HID capsules) in the same way you'd build regular quad biX setup; plus:
• One 3 way switch
• Two relays with an "always connected" pin
• Cable and connectors (I chose 16 AWG thickness; these are probably more than enough for "signal" level wiring for this DIY; might not be thick enough for "power" level wiring)

Since we will be creating a new harness that builds on top of the existing 2 harness sets, some crimping tool, heatshrink, etc. that you prefer for installing connectors at the ends of wires will be needed. For some of the ends, I also soldered the wires inside the crimped connectors for good measure.

Table of contents

• Parts list: posts #2-#5
• Example OE connector check: post #6
• Steps for dual filament OE bulbs (e.g. 9007 & 9004): starting at regular biXenon, post #7, to reqular (full-time) quad, post #8, to 3-way switchable quad, post #9.
• Steps for single filament OE bulbs (e.g. H7 low + H1 high): starting at regular biXenon, post #66, to regular (full-time) quad, post #67, to 3-way switchable quad, post #68.
• Example switch setup through the firewall, post #10 - 14
• Discussion on what 3-way switch to choose, post #31
• Variations for the dual filament bulb, post #38 - 40

[satrya]

Examples for the parts on the list above:

For the 3-way switch, I chose this "Sierra International RK19460 SPDT Illuminated On-Off-On Marine Rocker Switch" from amazon. See post #17 on what to look for, and examples of what not to get.

Here's the bottom view of connector I got, placed on top of the labeling that came with it:


In addition to the single pole ("SP", i.e. one channel) dual throw ("DT", i.e. 2 switch positions) pins, it has an additional pin that illuminates any 1 of the 2 positions that are closed. Given the location of the switch on the dash I plan to install, which is a few inches below the steering column axle, I didn't want to be bothered with another light in my instrument cluster.

The switch has a different enough texture and shape compared to oem switches nearby, that I could just use tactile feedback to find the switch and know which position is selected based solely on touch. So, I modified the switch not to light up. There are 3 springs inside that serve as the connector for the bulbs. I simply removed them.

[satrya]

Relay with "always closed (=connected)" pin

Next, is the 2 relays. There are 2 reasons for these 2 relays

The primary reason, is that I want the 3 way switch to allow for:

1. Only the primary biX pair lit up
2. Only the secondary biX pair lit up
3. Both pairs lit up

The 3rd one is there when I want to transition from one pair to another, but don't want a sudden illumination drop because the new pair still needs to warm up. That way, if I switch from highway to surface street, and want to use the pair that best suits the condition, I can "warm up" the proper pair while still keeping the current pair on.

A regular 3 way switch only allows the first 2 options above, but not have the "both" (/quad) option.

Most relays, however, come with an "always open" pin (numbered 87). Here are 2 examples of relays with an always closed (numbered 87a) pin. They happen to also come with the more common pin 87, but we will ignore this pin for this DIY.

Absolute RLS125 12-VCD Automotive Relay SPDT 30/40A (from amazon):

Note the circuit diagram on top of the package, with both pins 87 (-->ignore) and 87a (-->use).

[satrya]

Another relay

Here's another relay model that also has 87a. I bought both types just in case.

Omix-Ada 17237.02 Relay (from amazon):

The diagram on the packaging is a little easier to see from this picture.

[satrya]

Socket for the 5-pin relay

Since relays can fail over time, it is a good idea not to hardwire the relays into the custom harness. A socket for the relay helps. Most local stores only sell sockets for the more common 4 pin relay (that doesn't have 87a pin), so here's another amazon buy (I could've used Digi-Key, Newark, or other electronics component sites):

Absolute SRS105 5-Pin 12 VDC Relay Socket Interlocking Style

[satrya]

Starting point: single biX pair

If you already have a single biX pair setup, ignore this step.

Otherwise, this is probably an important step: figuring out if the biX harness pins are correct. Possible issues include physical connectors compatible with more than one system (such as the 9004 and 9007, which shares an identical harness but the pins could be incompatible), and whether the oem wiring is switched ground or switched positive.


Model year 2002-2003 Subarus, for example, is a 9007 switched ground, which requires this check.

Take one of the oem connectors that feed your oem low/high halogen bulbs like this one:


Then, go through all the oem headlight switch positions: off, parking light, low beam, high beam, and flash-to-pass. For every position, probe the oem connector pins to see which pairs give out positive and ground using a multimeter.
High beam and flash-to-pass should produce identical results.

Here's an example of how it looks on the 2002 bugeye wrx (Subaru)


Then, using an independent power supply (in the comfort of your home), feed the "signal" connector of your regular biX harness with those combinations, and check to see if the ballast ignites the HID and/or if the solenoid is activated.

For one of my 9004/9007 harnesses that came from TRS, the pin assignment started with (left to right) red-white-blue:


Try all possible combinations, and note which ones have both low and high beam working properly. There are combinations where low beam activates solenoid, or only the high beam setting can turn on the HID. Keep going until you find the right combination. Keep a note like this to make sure you're not going in circles:



And the winner: red-blue-white (your harness may vary)

[satrya]

Single biX pair setup

If you already have a quad setup, you will have this and more already.

Otherwise, following the previous step, you should end up with this:

The 3-way switch behind the firewall is for later. The parts boxed within "BiX pair #1" should be your regular biX pair setup. There is an additional box called "switched positive" that provides +12~13.8V only when the engine is running. We'll use this later.

[satrya]

Common quad biX setup

The common quad biX setup simply replicates the first biX pair. If the first pair uses the driver side oem low/hi beam connector as the signal input, then the second pair could use the passenger side.

[satrya]

3-way switchable quad biX setup

With the additional parts described, we will end up with a setup that looks like this:


Note that one of the pins on the "signal input connector" for both Harness#1 & #2 (e.g. 9004/9007 harness that TRS sells) gets cut, and re routed to the "power" side of the 2 new relays. One side connects to pin 30, and the other connects to pin 87a. If you put a connector, then this change is reversible.

On the 2 new relays, one of the "signal" pin, i.e. pin 85, connects to the switched positive source, and the other "signal" pin 86, connects to the new SPDT switch behind the firewall.

[satrya]

For the 2002-2003 Subaru Impreza (and possibly up to 2009), there is a reasonably accessible grommet on the firewall just above one of the engine mounts. In my case, it is inconveniently hidden behind the top mount intercooler and strut tower bar:

[satrya]

With the bottom of the driver side dash panel removed, the wire is snaked in from the engine bay via the firewall. The grommet is located approximately behind the center console (yellow x). The tip of the insulated cable is covered to prevent the 3 individual wires from snagging and not making it through.

[satrya]

There's a blank panel next to the oem foglight and cruise control switch. Popping the panel out reveals a hole, whose height needs to be extended by about 3mm to accommodate for the 3-way switch chosen.

[satrya]

The 3-way switch installs by interference fit onto the opening, like so:


The 3 wires coming out of the cable snaked through the firewall connects to the switch via spade connectors:

[satrya]

Recalling this diagram:


I chose to route the switched ground for the low beam signal (right most on the table above) to the custom wiring. Cut that line on the TRS harness side, and add a connector so you can revert to regular TRS harness mode:


Do the same on the other TRS harness.

[satrya]

That is all. With this, the 3-way switch allows for one or both biX pairs to turn on, and the appropriate biX set will operate low and high as needed.

Primary:


Transition (both on):


Secondary: