Toyota Prius 2004 EV Electric Vehicle Button PDF Installation Instructions

Time and Difficulty: I found the install to be moderately difficult and pretty time-consuming (about 3 hours); others have found it simple and report they have done it in as little as 30 minutes. Your experience will depend on your familiarity with the tools and electronics. I, personally, found insertion of the connection pin into the HV ECU plug to be difficult and almost got the first pin irrevocably stuck in the slot. I spent quite a bit of time with that part alone. I also found threading the wire behind the dash to be fairly tricky. I think the average person, not encountering any problems, could do this job in about 1-1½ hours.

Procedure in Brief:
1) Remove bottom cover of steering wheel
2) Locate and unplug flasher plug
3) Open plug and remove 1-3 unused connector pins
4) Reattach steering wheel cover
5) Dismantle part of dash (vents) and remove lower glove box
6) Locate HV ECU (gray plugs) and remove lower plug
7) Solder wire to connector pin and insert into ECU plug (#27)
Splice EV button ground wire into ECU plug ground wire (#1)
9) Plug ECU plug back into the ECU
10) Thread wire behind dash to opening near dimmer switch
11) Attach switch to cover and solder wires in place
12) Reassemble the dash
13) Test

Procedure in Detail:
*Review ALL steps before proceeding and be sure you understand all terms used and you’ve looked at all diagrams and pictures.
1) Remove the bottom cover of the steering wheel by releasing the steering wheel adjustment handle and unscrewing the silver screw in that recess Then, turn the steering wheel 90 degrees right and remove the black screw that becomes visible on the right side of the steering column.
Then turn the wheel 180 degrees left (90 degrees from normal position) and remove the black screw on the left side of the steering column. Carefully pull down on the lower portion of the steering column cover until it releases. Mine was a bit stiff/stuck to the upper part and you may need to carefully use a butter knife or screwdriver to start prying them apart.

2) Locate and unplug the white flasher plug visible just on the left side of the bottom of the steering column.
3) 2 little clips keep a cover locked in place. Pull those apart and remove the cover. Inside you’ll see lines of silver connector pins–some with wires attached, some without. You should remove between 1 and 3 of those pins–2 is probably safe, 3 might be better, since if you plan to install an OEM button at some point, you’ll probably need more pins for that. (You need one pin for the procedure, but it’s handy to have a back-up.) To remove the pins, you can use your paper clip to start the process of sliding them out, and then they just pull right out.

Stick them to a piece of tape or put them somewhere secure so you can find them later. Snap the cover back into place, and plug the flasher plug back in.
4) Replace the steering wheel cover by reversing the process. Be sure everything’s aligned properly and that there are no gaps.
5) Now you’ll need to dismantle part of the dash to get access to the ECU and other areas. First, open the top and bottom glove box doors. Squeeze the inside sides of the lower glove box together to get the catches past the portion of the dash frame that keeps the door from falling all the way open. Then pull the entire door straight toward you – it will unclip from the hinges at the bottom of the glove box.

You may also need to unclip the little hydraulic piston that keeps the door from falling open too quickly. Next, grasp the bottom of the silver vent piece next to the glove box. Pull it toward you firmly. It should unclip at the bottom first. Then pull the whole unit straight out. You’ll eventually need to remove the driver’s side (far left) vent piece as well. Finally, remove the smaller square plastic piece just below the passenger side vent–it pulls straight out…

There’s a small catch on the right side of the plug that you need to squeeze in to get the plug out. Remember the orientation of the plug so you can properly identify the holes where you need to insert the connector pin and wire. Once removed pull it carefully through the lower most opening (where you removed the square plastic piece below the vent piece),,

Download Toyota Prius 2004 EV (Electric Vehicle) Button PDF Installation Instructions