The Disclaimer: This is a write-up of what I did. If you try this on your own truck, I cannot take any responsibility for any damage you may incurr. If your try this mod, you do so at your own risk.
First, I would like to thank rcbs204 for the idea of making a circuit board using LEDs. I would have never thought a circuit board could fit in the switch housing.
For those of you who do not want to tackle this yourself, rcbs204 will be selling an easy to install kit once his through R & D is complete. Click on this link for more info.
For those of you who like the challenge of doing it yourself, here's what you'll need:
1) Copper Clad Board (To make the circuit board)
2) Copper Etchant (Aluminum Persulphate)
3) Etch Resistant Pen
4) 6 LEDs I used the following.
Type - NTE Part No. 300335) Resistor - 470 Ohm
Size - 3mm T1
Colour - Clear Orange
Brightness - 100 MCD (I Think)
Forward Voltage (VF) - 2.6V
Forward Current (IF) - 25mA
Viewing Angle - 10 degrees (A wider angle would be preferable)
6) 2 female crimp on connectors - Molex 16-02-0103 (I could not find these connectors locally, so I used Molex 39-00-0039 and used a dremel tool to make them fit.)
7) 2" OD hole saw
8) 0.033" drill bit
9) Tapered Drill Bit (To enlarge centre hole)
10) Drill (Preferably a drill press)
11) Small plastic container
13) Soldering Iron
14) 22 Ga wire
15) 18 Ga Wire
16) Wire Cutter
17) Wire Stripper
18) Crimping Tool or Pliers
19) Neoprine weatherstripping. (You can probably use something else, but it worked for me.)
Use 2" hole saw to cut out a circle from the copper Clad Board.
You will end up with a 45.7 mm (1.8") circle which will fit inside the 4X4 switch. Some filing may be required.
Use the tapered drill bit to enlarge the center hole to 18 mm (0.7").
I made the centre hole too small and ended up grinding it bigger with a Dremel tool. The centre diameter must be large enough to clear the switch shaft.
Cut the circular circuit board in half.
I used a utility knife to cut the circular board in half. This took a bit of work. I'm sure a fine toothed saw would have been quicker, but I wanted a really clean cut.
File two notches into the round edge of the circuit board.
The notch on the left is approximately 17 mm up from the flat edge, and the notch on the right is approximately 13 mm up from the flat edge. You can adjust these measurements to suit. The notches are there to clear two ribs inside the switch housing. You will be able to see the ribs in a picture below.
Step 4: Draw the circuit using the etch resistant pen.
The circuit is simply 6 LEDs and a resistor in series.
The diodes that light the "H2", "H4", and "L4" will be near the outer curved edge of the circuit board. The centre of each of these LEDs must be 2.5 mm from the outer curved edge. The LEDs that light up the pointer are the ones closer to the inner curveed edge of the circuit board. Their center is spaced 12.5 mm from the outer curved edge of the circuit board, or 100 mm away of the other LEDs.
Drill 0.033" holes to mount the diodes, resistor, and connecting wires.
Use a drill press, if available, to avoid breaking the fine drill bit.
In a small plastic container which is big enough to hold the circuit board, mix etchant solution as per instructions that came with the etchant.
Emerse circuit board into etching solution until unprotected copper is etched and the drawn circuit remains.
Insert components, and solder.
The diodes that light up the "H2", "H4", and "L4" should stick up above the circuit bord no more than 19 mm. The other diodes which light up the pointer should stick up above the circuit board no more than 14 mm.
Note the flat side of the doide lens denotes the cathode. That is the negative side. Make sure the diodes are oriented to allow current to flow from one end of the circuit to the other.
Notice the circuit board on the side with the components also has copper trace where the connecting wires will attach. This will allow the ends of the wires to be soldered on the component side of the board, allowing the wires to exit the back side of the circuit board.
Trim off excess leads from components.
Remove 4X4 switch from dashboard.
I just slid my fingernails where my finger is pointing in the picture below and pulled.
Unplug the connector behind the switch and bring it inside.
Remove the small brown plug at the back of the switch by inserting a small screwdriver into the slot and turning counterclockwise 1/4 turn. The only picture I have of this plug is with the back already removed.
Insert two 22 Ga wires, one in each of the two holes in the plug. The wires are to be inserted from the side of the plug that faces inside the switch.
I used wires from a telephone cable.
Wrap each wire through each of the two slots, under the plug, and back up again. Wrap the wires as tightly and as deep into the slots as possible.
Remove the back of the switch by carefully prying the tabs with a small screwdriver. One of the tabs is shown on the picture below. There are four tabs. Be careful not to break them. Also be carful of the spring loaded shaft inside the switch. Do not pull off the front selector, as doing so will allow the narrower part of the two piece shaft to fall out and a spring loaded ball bearing to go flying and become lost.
Insert wire and plug back into the back cover of the switch. Turn the plug 1/4 turn clockwise to lock in place. If the plug does not turn, the wire is not wrapped flat enough on the plug.
Trim the 22 Ga wires to an appropriate length and solder them to the circuit board. Solder the red wire to the positive lead of the first diode in the series circuit, and the black wire to the negative lead of the last diode of the series circuit.
Look at where the brown plug was installed. Notice the 4 pinouts on the back cover of the switch. Take note of which pin is connected to the positive wire, and wich pin is connected to the negative.
In my case, pin 1 is negative, and pin 3 is positive. The polarity of the pins can be switched by removing, repositioning, and reinserting the plug.
Insert the circuit board into the switch. This can only be accomplished if the selector is between "H4" and "L4", closer to "L4". This is due to the tabs on the shaft of the switch.
Cut 3 small pieces of neoprene weatherstripping, and stick them inside the switch housing to keep the circuit board in place as shown in the picture below.
Snap the back of the switch back on, making sure the wires to the circuit board does not interfere with the operation of the switch.
Crimp the Molex connectors onto two stranded 18 Ga wires.
Inside the Tacoma, locate the connector for the 4 x 4 switch.
Using a jeweller's screwdriver, pry off the white retaining clip.
Insert the two Molex connectors into the empty slots. Take note of the polarity.
In my case, Slot 3 is positive, and slot 1 is negative. Slot 1 is the furthest slot to the right in the picture below.
Remove the HVAC control panel.
Remove the cover to the right of the stereo by prying at the top of the cover.
I used my fingernails.
Place your finger in the hole behind the cover and find the clip at the upper right corner of the HVAC control panel, and push. That corner of the control panel should pop out.
Place your finger in the hole where the 4x4 switch goes, and do the same thing for the left upper corner of the HVAC control panel.
Remove the HVAC control panel and unplug the connectors from the back.
Fish the two 18 Ga stranded wires from the 4x4 switch connector to the HVAC control panel location.
On the connector with the thinner wires, find the green and the green/white wire.
Remove the retaining clip from the connecting by prying it off with a jewller's screwdriver.
Then remove the green/white wire from the connector by inserting a jewller's screwdriver in the receptacle end and pressig down on the plastic retaining tab.
Piggy back the negative wire from the 4x4 switch connector to the green/white wire.
I losened part of the crimp on the green/white wire, place the negative wire from the 4x4 switch connector into the crimp, and re-crimped it.
Insert the two wires back into the connector.
Do the same with the solid green wire and the positive wire from the 4x4 switch connector.
Reinstall the plastic retaining clip.
Plug the connectors back into the HVAC control panel, and reinstall the control panel.
Plug the connector back into the 4x4 switch and reinstall the switch.
You're done: Turn the lights on, and the switch will look like this.
1) I find the lighting not very even. A wider angle LED would probably work better.
2) The LEDs are a bit brighter than the lights on rest of the dashboard. It also does not dim as fast. A larger resistor may help.
3) The clear orange LED matches the OEM dash colour perfectly.