Nissan Repair Questions? Ask a Mechanic for Answers ASAP
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The reversing sensor has a self test feature which will give the 3 second sound you are hearing, this tests the speaker and audio system and confirms this is working, but as it is sounding for three seconds this indicates that one of the sensors has failed. This may be a coincidence or it may have been fro a surge when the battery was connected. It is sometimes possible to test the sensors by placing the vehicle in reverse and the gently touching the sensor. an operating sensor can be felt to gently pulse, but sometimes this can be so gentle it is not always detected.
Another possibility is that the unit itself has failed, and again this may have been from a power surge, but that would be rare.
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