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radiator fan run non stop after engine off

Discussion in 'Gen 2 Prius Main Forum' started by Sun Chanras, Jan 3, 2018.

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  1. Sun Chanras

    Sun Chanras Junior Member

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    My Prius 2007 has a problem with radiator fan, it still running when engine turned off. I removed all the three relays that control the fans. But the fan still running until I unplugged the 12v aux battery at the rear of the car.
    Any possible short circuit or other problem?

    Thanks
     
    #1 Sun Chanras, Jan 3, 2018
  2. valde3

    valde3 Senior Member

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    If you pulled the three correct relays and fan(s) still run there has to be a short circuit. Any modifications or accident damage to the wiring? How long have you had it? When did the problem start? Do the fans start to run as soon as you plug the 12V battery back?
    Try to pull the 30A RDI, 30A CSD FAN, or 7,5A ECU-IG fuse and see if it stops.
     
    #2 valde3, Jan 3, 2018
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  3. Sun Chanras

    Sun Chanras Junior Member

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    @valde3
    I have it 4 weeks ago after I came back from a long holiday trip, I turned off engine but the fan still run full speed, at that time I thought it was because the engine still hot and the ECU need to keep fan run little bit more to keep the engine temperature down, but it was not, it was running until the aux 12v battery dead. next day, I have to use my neighbor's car battery to jump start the car. After jumping start, the car still runs with fan at full speed, I got the car to 3 nearby mechanics but they got no clue. The fan still run full speed and I have to use the car to work every day when I stop the car I have to unplug the aux 12v battery to prevent it from dying. One week later, the fan back to normal until today, the fan starts getting stuck again and I have to unplug the aux 12v battery to keep it from dying.

    @valde3
    Yes, the fan starts immediately when I plug the 12v aux battery back.
    I will try to pull 30A RDI, 30A CSD FAN, or 7,5A ECU-IG and will update you the result.

    Thanks
     
    #3 Sun Chanras, Jan 3, 2018
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  4. edthefox5

    edthefox5 Senior Member

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    You have to identify which of the 2 fans is constantly running, there’s the radiator fan and the ac fan.
    The 30ARDI FUSE is the radiator fuse. The 30ACDS is the ac fan fuse

    If it’s the rad fan has to be a bad Fan relay 1 if it’s the ac condenser fan there is a water temp switch that if on will turn the ac fan on until the engine is cooled. Your engine maybe oveR heating. Or that switch s bad.Do you smell any burning. Is the water pump belt intact and is that pump ok and is there coolant in the engine. You have to take the black plastic cover off the top of the rad and open the rad cap for coolant level.
    The temp sensor is mounted to the rad on the passenger side below the horn but can’t remember if it’s on the front or the back of the rad. I think it’s the back. I do know it may have incurred damage to the swx wiring if the car has had front end Collision damage. Seen that before on this site.
     
    #4 edthefox5, Jan 5, 2018
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  5. valde3

    valde3 Senior Member

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    It was mentioned in that pulling the three fan relays won’t stop the fans from running. That basically means that the problem has to be with the actual wires going to fan(s) not the control side of relays.

     
    #5 valde3, Jan 5, 2018
  6. edthefox5

    edthefox5 Senior Member

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    Yes I saw that but looking at the print that’s not possible so I think he’s not pulling the right relays.
    Unless they have been rewired.
    Let’s see which fan it is by pulling the correct fuse.
     
    #6 edthefox5, Jan 5, 2018
  7. valde3

    valde3 Senior Member

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    Yes that’s why I asked in my first post if he’s pulling the correct relays. I also asked about pulling the fuses. And he did already tell that he will tests pulling the relays.
     
    #7 valde3, Jan 5, 2018
  8. edthefox5

    edthefox5 Senior Member

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    I saw that question you asked and I agreed. Just wanted him to confirm for sure by pulling the fuses. I bet its a salvage car.
     
    #8 edthefox5, Jan 5, 2018
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