MAKE pal Douglas sent in this awesome Prius “Stealth mode” mod – check it out!Move the steering wheel tilt lever to the unlocked position. Remove the screw which it previously covered…
Turn the steering wheel 90 degrees right of center. Remove the screw on the right side of the face of the steering column, behind the wheel. Turn the wheel 90 degrees left of center and remove the similar screw on the left side.
Press inward on the lower half of the plastic steering column cover, just below and forward of the control stalks to disengage the fasteners. Pull gently down; the lower half of the cover should come loose and move down 3-5cm. It requires some wiggling but little force.
Unplug the white connector leading to the turn signal stalk by pressing in on the latch while pulling down.
Remove the cover from the connector by gently pulling the two retaining tabs outward.
Remove one of the unused pins from the connector by pressing gently inward on the metal retaining tab with a small sharp object. The pin should slide out easily. Set the pin aside and re-assemble everything else.
Remove the lower glove box using the procedure in the owner’s manual. (See the section which explains how to change the interior air filter.) Remove the vent panel on the far right of the dash by pulling straight toward you; it requires considerable force. Remove the small lower panel by reaching behind it and pushing down on the retaining tabs.
Remove the vent panel on the far left and one of the two blank switch plates.
Inside the rightmost portion of the dash you should see three ECMs with many wires leading to them. Unplug the lowermost of the four connector plugs from the rightmost ECM (designated H14).
Using a curved wire hanger or similar object, pull two-conductor 24ga. wire from the left side of the dash to the right. Work carefully to avoid damaging factory wiring. Leaving at least 20cm extra on each end, secure the wire to the existing harness or other convenient structure.
Mount a normally-open SPST momentary-contact switch to the blank faceplate, and connect it to the left end of the wire.
Connect one of the conductors on the other end of the wire to any conveninent ground. I used a spade lug under the 10mm screw just left of the ECMs.
Attach the other conductor to the pin removed from the steering column. Test continuity with a multimeter. Though the pin is designed to connect to unstripped wire, I could not get a reliable connection without the proper crimp tool. Stripped wire and a tiny dot of solder did the job. Hold the ECM connector with the wires up and the white retaining strip toward you. Pry the retainer toward you with a small screwdriver; it will only move about 1mm. Insert the new pin, open side toward you, in the second hole from the right on the row closest to you (designated #27). Push it down until the head of the pin is just below the connector housing.
Push the retaining strip back in place. Plug the ECM connector back in, pushing firmly until you hear and feel a click. Verify correct operation then re-assemble the dash. Thanks to Evan Fusco for the documentation I used during this project.
Douglas Henke – firstname.lastname@example.org