Volvo VNL 780 loss power and speedometer

Discussion in 'Volvo Forum' started by JayFlow116, May 22, 2017.

  1. JayFlow116

    JayFlow116 Bobtail Member

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    I have 2006 Volvo VNL 780, am getting sudden power loss and loss of speedometer, engine brake and loss of cruise control. I heard speed sensor could cause symptoms except, I am not able to throttle at all and engine stays in idle range with no pedal response what so ever.


    Any help?
     
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  3. JayFlow116

    JayFlow116 Bobtail Member

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    Side note: read in other threads that engine could rev up to 1500 rpm. Not mine
     
  4. boneebone

    boneebone Road Train Member

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    Your Accelerator Pedal and/or your Pedal Position Sensor could be bad or going bad.

    The symptoms you are describing are common when those parts are failing.

    It could also be your Speed Sensor failed, in that case your Speedometer will not work and your truck will go into Limp Mode, but your truck should still accelerate.
     
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  5. JayFlow116

    JayFlow116 Bobtail Member

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    This is what my tech is saying, speed sensor should not affect throttle input. Says ecu may have bad pins or broken solder. Could ecu malfunction like so if the power is not returning out from ecu? He says ecu is not outputing 5v when condition occurs, but all wiring and plug is giving 5v into ecu but not responding back to truck
     
  6. Snailexpress

    Snailexpress Road Train Member

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    Johny41 Thanks this.
  7. JayFlow116

    JayFlow116 Bobtail Member

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    Thank you. Im going to check out the issue with the terminating resistors.
     
  8. nasriza

    nasriza Road Train Member

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    What's the code that's popping up when this is happening first of all please check u don't have a shorted Qualcomm cable for one maybe an old one. Second make sure the plug in the speed sensor it's making proper contact. I've never replaced one accelerator pedal in 10 years working of Volvo they almost never go bad
     
  9. JayFlow116

    JayFlow116 Bobtail Member

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    I changed engine Ecu and problem continued. Getting a Vehicle ECU code as MID 144 PSID230 FMI4 , simultaneousley with an Engine ECU code of MID128 PID95 FMI0. At the time of occurence a check light module alert comes up and then thes codes come up.
     
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  10. boneebone

    boneebone Road Train Member

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    I guess you've been lucky, I had to replace mine about 5 years ago because it would intermittently cause my cruise control and engine brake not to work.

    When that happened, the check engine light would come on until I pressed on the pedal again and the ECM received a signal again and it would start working normally again until the next time.

    It eventually got so bad I finally replaced it and it has been fine since.

    My friend's 200O Volvo Accelerator Pedal is starting to go out on him too, same symptoms that I had and his code says Accel Position Sensor.

    It ECM doesn't set a hard code at first, but it will eventually.
     
  11. JayFlow116

    JayFlow116 Bobtail Member

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    I changed the Accel Position Sensor first. It temporarily helped, but was still loosing the accelerator response along with speedometer signal
     
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