79 Z/28 windshield wipers won’t stop

Discussion in 'Troubleshooting & Diagnosis' started by Daniel I, Dec 26, 2019.

  1. Daniel I

    Daniel I New Member

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    Hi,
    So recently I put in a new windshield wiper motor because my other one was shot, but after installing the new one no matter what position the switch is in it doesn’t stop, in high it will go faster but in the other two positions it stays in low. I tested for voltage at the connector and there’s 12 volts in all three positions. Would this be a bad switch?

    thanks,
    Daniel
     
  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    The wiper system is fairly complicated. A number of different things can cause the wipers to continue running. Usually it isn't the fault of the switch. The washer section has the ability to override wiper motor shutdown if the wash cycle doesn't complete. If you have delay wipers, the park switch inside the wiper motor can do it too.
    The wiper motor gets 12 volts anytime the ignition is on. The wiper switch then supplies ground to the various windings to make it run at a specified speed.
    Some of the GM service manuals have a step by step procedure for troubleshooting wiper problems. The best on I ever found was the GM factory manual for a 1979 Impala/Caprice. I no longer have that manual, but other manuals should also have that information.

    I suggest getting a good factory manual and troubleshooting step by step. The other way to do it is the shotgun approach which gets expensive and gives poor results as you never know for sure if any parts you replace are any better than the ones you take out.
     
  3. Daniel I

    Daniel I New Member

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    Ok thanks! How do you know if you have delay wipers?
     
  4. Gary S

    Gary S Administrator Lifetime Gold Member

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    Does the wiper switch had a rotary knob to set delay time? If so, it is a delay system. If the switch is a simple slider, it doesn't have delay.
     
  5. Daniel I

    Daniel I New Member

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    Oh ok, it’s just a slider so no delay, thanks!
     
  6. Daniel I

    Daniel I New Member

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    So I’m the off position would it cut out both grounds? Because after reading it again with a multimeter it still is grounding it.
     
  7. Gary S

    Gary S Administrator Lifetime Gold Member

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    This is where you need the service manual. It describes step by step how you put the system through tests to determine where the problem is.
     

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