Back Up sensors - erratic?

Discussion in 'LR3' started by sunlion, Sep 13, 2007.

  1. sunlion

    sunlion Member

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    Has anyone else noticed erratic behavior with these sensors? They do not engage every time the truck is put in reverse. I've had the dealer look into it and they said it functioned properly. It seems that a sequence of steps needs to be followed for the sensors to turn on, namely step on the brake, move from P to R then manually release the parking brake. It often does no engage going from D to P or if the gas pedal is pressed to disengage the ebrake. I have had not one but two encounters with my brother's mail box because of this, the last of which left a nice dent in my lower tailgate.
     
  2. schafari

    schafari Full Access Member

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    Erratic and ultimately failing backup sensors is not completely uncommon. IIRC, there is a speaker relaated failure and a control unit failure. Regardless, anytime you move into reverse, the sensors should activate. If they don't, there is a problem. If you don't get the "I'm on" chime when you move the gear shift to reverse, there is a problem. Look at the button, is it flashing or steady? If it is flashing, that indicates a failure. If you have intermitent problems, has the sound of the beep or chime changed? That would indicate eventual failure likely.

    (Not to be a jerk. . .but do you really depend on the sensors to gaurantee you don't hit anything while backin? If they don't warn you. . .you proceed to back into a mailbox. . . twice? As a father of three very small children that may or may not set off the sensors. . .this scrares me to no end. . .)
     
  3. grommet

    grommet Full Access Member

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    sunlion, what year? The logic has changed twice. The 2nd version just turns on when you drive very slowly. The original version only activates when you do a specific park/reverse manuever. For the 3rd version (default on 2007+), it's back closer to the original logic... since people complained the 2nd version activated too much by stray noise.

    At least on the 3rd version, you can press the button to force an activation. (The button will light to confirm.)
     
  4. sunlion

    sunlion Member

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    My LR3 is 2005. I don't depend on the sensors alone but they should pick up things below the view of the tailgate. I have a lot of small children around also and I make sure none are anywhere close when I'm backing up.
     
  5. grommet

    grommet Full Access Member

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    If you have a 2005, the PDC can be upgraded to the improved logic. (Via module replacement.) There is a TSB article for 2005 about the PDC not activating all the time; just take it in with this specific complaint. If you are still in warranty, you'll be fine. I'm not sure if you'll get the 2nd or 3rd version of the logic now... either one will be better than the 1st flawed implementation.
     

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