The new-to-us Peugeot 807 is a rather big car, and the view to the rear when backing up is limited. Especially when someone is sitting in the middle back seat, and the car is loaded with a huge baby stroller. As is usually the case. So, when the neighbours related how their new car’s parking sensors rescued them from running over some small child in a parking lot, there was really no choice-our car needed that sixth sense.
I was surprised to find that after-market parking sensors are rather cheap, I paid about USD 20,- on ebay for a set that included four sensors, the main unit, a beeper, and the drill bit required to fit the sensors in the bumper. I chose a unit without a distance display, for two reasons. The primary purpose of this thing is to be an alarm that alerts you when you’re not paying attention. I wouldn’t be able to trust a displayed «5 cm», so that information would be almost useless, and clutter the dashboard. Also, I didn’t want the job of running a wire from the rear bumper to the dashboard.
Here is the step-by-step:
1. Locate the power source. Chose the left or right tail light to hook into. I chose the left one, but I imagine the right light will work just as well. Undo the light so you can inspect the wires to the reversing light. Mine were a black and one sky blue wire. Look inside the little compartment behind the light and locate the wires that feed the tail light unit. It will look something like below.
You can see the sky blue wire (+12V when reversing) is the third one from the top, and the black one (earth) is the fifth. Verify with a multimeter to make sure you fund the correct wires.
2. Connect the power. The power for the alarm unit needs to be connected to the reversing light’s power. The easiest is to use something like posi-taps. However I chose to open up the connector (just pull out the light blue piece) and soldered the power cable onto there. Black wire to earth (black) and red wire to +12V (sky blue wire).
3. System test. With the power in place, all the electrical work is done and the system can be tested. Hook up the beeper and sensors. You can fix the sensors tempararily with duct tape, and just check that it works as expected.
4. Remove the bumper pieces. The sensors will be installed in the three upper pieces of the bumper. First pry loose the two corner pieces on either side. Then undo the three torx screws that hold the longer center piece, and pry loose this also. It does take a bit of force, but they will come off.
5. Drill those holes. The poin of no return. At least in my bumper, the positions for the OEM alarm sensors were clearly marked. Two sensors go in the center piece, and one in each corner piece. Mark the center of each hole with an awl, then drill the hole from the outside.
The bumpers were made of too thick plastic for the sensors to be seated properly, so I used a dremel tool to grind off a bit of material from the inside.
6. Route the sensor wires. Push the cables into the hole in the bumper and down so they will appear under the car. Use a nylon cable tie to fasten the cable near where the sensor will sit, leaving 20 cm or so of slack. If you look from under the car there is a cable running up into the compartment where you hooked up the alarm unit’s power. There should be plenty of space to push the sensors’ wires up the same hole. Use cable ties to secure the wires under the car.
7. Reassemble. Mount the bumper pieces in reverse order as they were disassembled. Place the alarm unit somewhere safe inside the compartment, I found a perfect little pocket as indicated below:
Now only the beeper remains to be installed. You can probably put it right next to the main unit. I chose however to put it in the rear speaker compartment, fixed to the speaker with cable ties.
Finally, the end result looks like this: