DIY: Add Steering Wheel Controls

If you can strip wires and unscrew things, you can do this. Depending on your choices, cost is as cheap as $150 or as much as $900. First, the before/after:

exist on this topic, but when I did the mod, I found them difficult to follow. If this works or doesn't work, please add to this thread with photos and sugggestions and I will edit this original post to make it clearer to future DIYers.

Overview:

1. Run three wires from your steering column to a harness behind the stereo.
2. Disconnect the battery and remove the airbag. Plug in the steering wheel controls.
3. Cut your airbag cover to fit the new shape of the steering wheel controls. Then, add a cover hide the modified airbag cover, which won't be perfect. Alternatively, you could buy a used airbag for about $300-$350 and resell your existing airbag to recoup some of that cost.

Stuff you need:

• 9 feet of small-gauge wire
  $14 BNTECHGO 18 Gauge Silicone Wire Spool Red 25ft and Black 25ft 2 Separate Wires Flexible 18 AWG Stranded Tinned Copper Wire
  such as this.
• Steering wheel controls in black (part #842500C010C0) or brown (part #842500C010E0) to match your wheel. These are about $100 used on ebay but they show wear easily so they might look crappy. The type with temperature controls work but do not seem to control the temperature, so look for the type with the blank above the right side controls.
• CHEAP PATH ($50): A stick-on cover for your wheel (black, carbon fiber) and optionally steering wheel controls (black, carbon fiber). You'll cut your airbag cover to fit and hide it with the cover. I can't address how the cover might impact safety during airbag deployment, so use at your own risk. You don't need the cover if you don't care how it looks.
• EXPENSIVE PATH ($300+): An airbag with the attached cover. I bought mine from airbags-usa.com. Ebay has them, just be sure to get the type with the cut-outs for the controls.

Step 1: Running the Wires
All Tundras are pre-wired for steering wheel controls from the steering wheel to the steering column. However, Toyota didn't run the wires all the way to the harness behind the stereo, so you have to do that now.

1. Cut 3 lengths of 3ft small-gauge wire and strip back both ends about an inch.
   
2. Start the engine so you have power steering. Turn your steering wheel to the left and right to expose the two screws on the upper sides of the steering column. Remove them. Turn off the engine.
   
   
   
3. Pop those plastic side panels off the steering wheel column. They just pull down once the screws are removed.
   
4. Find the J45 black harness on the right side of the steering wheel column closest to the wheel. Unclip it and pull it out. Next is someone else's pictures. It's the black harness on the left, also shown in the following diagram.
   
   
   
5. See the three pins marked on the above diagram at positions 4, 5, and 6? The right side of the bottom row when J45 is installed. Those are the pins you need to run to the harness behind your stereo. You might or might not have wires in them.
   
   IF YOU HAVE WIRES (like in the above picture): Pull back the cover from the wires in positions 4, 5, and 6. Use a
   $10 Quick Splice T Tap Wire Connectors for Wiring Self Stripping Disconnect Electrical Connect Assortment Kit 22 20 18 16 14 Gauge Car Speaker Taps Insulated Terminal (120Pcs) lkelyonewy
   vampire tap or T-tap to connect 3ft of small-gauge wire separately to the wires in positions 4, 5, and 6 as shown in the diagram.
   IF YOU DON'T HAVE WIRES: Fold the end of the stripped wire over to make a "good enough" harness connector. Push them into positions 4, 5, and 6 in the J45 harness and verify that you can kinda see the wire on the other side of the harness. Use a zip-tie to bundle your new wires with the old wires and stop them from pulling loose.
   
6. Pull out your stereo without disconnecting the wires.
7. Find the K3 harness connected to the back of the stereo. It has 20 pins, 2 row of 10 each. Fold the other end of the three stripped wires over to make a "good enough" harness connector. Connect the wire from pin 4 of J45 to pin 6 of K3 (or ground). Pin 5 of J45 goes to pin 7 of K3. Pin 6 of J45 (light green) goes to pin 8 of K3. Zip tie your new wires so they don't come loose.
   
   This is the K3 connector:
   
   
   
   If you look in the radio part of the harness, you should see that it has some pins in positions 6, 7, and 8. That's what your new wires are connecting to.
   
   This is how mine looked. The red and black wires (in pins 7 and 8) at the top are the new wires. The third wire is missing because I ran it to ground, but it's probably easier for you to connect it to the harness:
   
   
8. Plug the harness back in and leave your radio loose in case the wiring didn't connect right.

The hard part is over!
Removing the Airbag

1. Use a pick or something to pull off the plastic panels from the sides of the steering wheel.
   
   
2. Use a T30 bit to remove screws from both sides.
   
   
3. Tilt the airbag cover forward from the top to expose the three wires holding it in place. Let's start by testing your steering wheel controls to make sure your wiring is good before going any further. Connect your steering wheel control harness at the top of the wheel. There will be one loose wire that doesn't go to the harness. If you touch it to ground, your truck honks. We don't seem to need this wire, so tape up the end and tuck it away.
   
4. Turn the key to ACC or whatever starts your radio. You don't need to start the engine. Turn on your headlights and check if the controls light up (they're dim). Make sure the controls work with your stereo. If they don't, it's likely a loose wire.
   
   You can test your connections by using a 12V DC voltmeter. Connect the positive clip on your voltmeter to the radio end of the wires going into pins 7 or 8 of K3. Connect the negative clip on your voltmeter to any ground on your truck. When you press the steering wheel controls, you should see the voltage change. If you don't see voltage change, that wire connection is probably loose. The left and right sides of the controls each use one of the two non-ground wires independently, so if one side works and the other doesn't, you know one of the two wires is loose and one is fine.
   
   
5. The controls work, so back to the airbag: Disconnect negative from your car battery so you don't accidentally pop the airbag in your face. Pull up the clips to remove the wires.
   
   
6. When removing the ground for the horn, you might need to use a tool to release it as shown here.
   
   
7. Set your airbag aside for now. Remove the left and right plastic pieces that were behind the airbag and set them aside.
   
   
8. Screw the steering wheel controls into the same spot where the plastic pieces were.

CHANGING THE AIRBAG
If you bought a new airbag designed for use with the steering wheel controls, connect it up and put everything back together.

If you're choosing to cut and hide your steering wheel cover, follow these additional steps:

1. Place your stick-on cover (black, carbon fiber) over the airbag cover and trace around it. Use a dremel or something to cut the airbag cover to the same shape as your stick-on cover.
   
2. Warm up the adhesive on the stick-on cover, remove the red strips. and stick it firmly on the airbag cover. If you want to also cover the silver emblem, buy a "black steering wheel emblem overlay".
   
   

If you've already done this, PLEASE double-check me and tell me any mistakes so I can correct them. If you do this yourself, please take pictures of anything that's not clear and add them so I can update the instructions. For example, I don't have pictures of the J45 harness with custom wires because I followed a different path.

 

Great write up, that’s how I did mine as well. It definitely seems more intimidating than it actually is to do!

 

Thanks for this super helpful writeup!

I am really considering the "cheap" route for this but I'm wondering how that airbag cover feels in real life? In the event of a crash are you afraid of getting a piece of ABS plastic to the face at 100MPH?

 

It feels ok to me. I assume it will flip up with the cover, but I'm not willing to test that.

EDIT: I contacted the seller to ask this question and updated the DIY with the potential concern.