Guides Parking sensors fault finding guide

Discussion in '1st Generation (2004-2011)' started by MichaelG, Monday 16th Apr, 2018.

  1. MichaelG Junior Member ☆ ☆ ☆ ☆ ☆

    Ireland Gman London
    Hi all. I recently bought an FR-V. The previous owner said the parking sensors stopped working years ago. I thought I'd look at it and try to figure out what the problem was.
    The symptom was; When placed in reverse the system would make its startup beep followed by a constant tone for about 30 odd seconds before going silent.
    The first step was to confirm the parking sensors were all working. Turn the ignition on but do not start the engine. Place the car in reverse gear. One by one bring your ear up to each sensor. You should hear a ticking noise if it's working. Mine all were, though I noted they seemed very quiet. For good measure I got under the car, unplugged the sensors and squirted some WD-40 in each connector block to ensure the connections were sound.
    Now it was time to hunt for the controller. I followed the wiring loom which you can see in the back wall of the spare wheel well. The controller is mounted behind the offside boot panel, just below the speaker. You must first remove the alarm sounder.
    Alarm sounder.
    Remove the bottom bolt and loosen the top two using a 10mm socket. Simply slide upwards to remove and then unplug the connector.
    Mounting location. Mounting full view.
    The controller can now be removed by removing the three 14mm nuts and reaching behind the cavity to get it out. You will find a Bosch controller.
    Bosch controller.
    I investigated the wiring connectors. Their functions are as follows. Black connector. Power feed in 0V = Black, + = Brown/red stripe, sounder feed = Green & yellow . Brown connector. Red & Yellow/green = Common power feed to all parking sensors. The remaining 4 cores are the sensor return signals, one from each sensor.
    Wiring connectors.
    The sounder is mounted just inside the boot pillar. The connector feeding it can found on the wiring loom.
    Sounder location. Sounder connector.
    The positive power for the controller is fed directly out of the reverse light bulb feed. The negative supply can be seen as the top black core bolted down with all the other negative wiring near where the controller was mounted.
    Positive power feed. Mounting location.
    I used a voltmeter to confirm that the supply to the unit was good, it was 10.5V odd which is probably fine. This points unfortunately to a failed controller.
    The unit is a Bosch 0263004147. This one was manufactured in August '07. Disappointing considering it is something that is only powered up very occasionally. I suppose I'll have to keep my eye on fleabay for a controller and hopefully once replaced the actual sensors will be fine.
    I'll update as and when I get it swapped.
    andy83, AlwaysTired and Ichiban like this.
  2. Ichiban Founder Staff Team

    England CJ Leeds
  3. MichaelG Junior Member ☆ ☆ ☆ ☆ ☆

    Ireland Gman London
    After a good amount of googling I managed to find a fault finding guide on a Honda Civic forum which seems to use the same dodgy Bosch afterthought system.

    To enter diagnostic mode connect the red cable coming out of the black block to 0V. It's the one that's taped to the loom doing nothing. Seen in this picture.
    Wiring connectors.

    Turn ignition on but do not start the engine. Put car into reverse gear.
    You will hear 7 beeps. Their meaning is as follows;

    Beep1 / Initialisation of diagnostic mode. Low tone (2s) + Pause (1s)
    Beep2 / ECU failure / Low tone=error, high tone= no error / Tone(1s) + Pause (0.5s)
    Beep3 / Power supply, Sensor supply, WD supply failure / Low tone=error, high tone= no error / Tone(1s) + Pause (0.5s)
    Beep4 / Sensor 1 failure / Low tone=error, high tone= no error / Tone(1s) + Pause (0.5s)
    Beep5 / Sensor 2 failure / Low tone=error, high tone= no error / Tone(1s) + Pause (0.5s)
    Beep6 / Sensor 3 failure / Low tone=error, high tone= no error / Tone(1s) + Pause (0.5s)
    Beep7 / Sensor 4 failure / Low tone=error, high tone= no error / Tone(1s)
    It then pauses for a couple seconds and repeats.

    You apparently can also set the speaker volume by disconnecting the red diagnostic mode cable from 0V while the diagnostic is running. It will then cycle through the loudness levels. Connect the cable back to 0V when the desired volume is sounded.
    Remove the car from reverse gear and then tape the red core back up to the loom when finished.
    I also learned that the sensors should be fitted to the back bumper with the connector plugs facing the following directions:
    If your bumper was ever removed I doubt they'd have been put back that way.

    All this work has taught me that just as I suspected, the controller has failed. But at least the knowledge is now on here for everyone in the future.
    Looking at the price of a new Bosch system compared to the many other seemingly better but cheaper options I can't help feeling I'll probably be ripping this one out and putting something else on instead.

    I'll post it if it happens but for now the controller is removed so no annoying beeps.
    Nels and AlwaysTired like this.
  4. AlwaysTired New Member Getting Started

    Brilliant Michael, an excellent guide.

    I've just managed to fix my rear parking sensors after reading this.

    The ECU needed replacing, just £27 for a used one from ebay.

    Many thanks.
  5. MichaelG Junior Member ☆ ☆ ☆ ☆ ☆

    Ireland Gman London
    I'm delighted it was of assistance. The FR-V isn't too easy to reverse due to bad rear visibility. I think because of that parking sensors are essential so I'm glad I helped you get them going again.
    AlwaysTired likes this.