setting Speedo switches

Discussion in 'Trucks [ Eighteen Wheelers ]' started by special k, Oct 5, 2013.

  1. special k

    special k Light Load Member

    89
    38
    Sep 6, 2008
    Ontario Canada
    0
    My odometer started acting up on friday. The speedo is accurate but the odometer is only reading half of the actual distance. I already had new Speedo that I had aquired but it's in mph. Mine is in klms. I put it in and it was off as expected. I set the dip switches to my original settings but it's still off by quite a bit. local dealer says it's pain and doesn't have any ballpark settings. Does anyone here have any ideas? The truck has 24.5 tires and 3.90 rear ends. I drove around a bit changing settings with no real improvement. It was still off by like 50 per cent. Any help would be appreciated. Thanks
     
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  3. Heavyd

    Heavyd Road Train Member

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    Make, model, and year of truck please!
     
  4. special k

    special k Light Load Member

    89
    38
    Sep 6, 2008
    Ontario Canada
    0
    sorry about that its a 2000 pete 379 with an 18 spd if that matters.
     
  5. CondoCruiser

    CondoCruiser The Legend

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    Rideandrepair and olpa77 Thank this.
  6. CondoCruiser

    CondoCruiser The Legend

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    olpa77 Thanks this.
  7. Heavyd

    Heavyd Road Train Member

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    Not 100% sure on Petes, but most modern trucks with electronic engines the speed signal is sent electronically from the engine. All the diff ratio, tire size and transmission output calculations are done by the engine and the speedo basically just displays it. The dip switches are for mechanical engines.
     
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  8. CondoCruiser

    CondoCruiser The Legend

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    So far I figured your tires turn 823.6101 turns per mile. One turn 6.4108 ft.

    Need to know them teeth on the speed sensor.

    It is heavy but he has the dip switch one. It picks up the signal off the speed sensor on the transmission.
     
  9. special k

    special k Light Load Member

    89
    38
    Sep 6, 2008
    Ontario Canada
    0
    The replacement speedo is an oem peterbilt unit. I actually have the original box but there isn't any paperwork in it. I found that site earlier but I wasn't sure about the tooth count. I know my speed sensor is on the back of the trans. The box has every thing on it but the actual manufacturer. If it matters this one doesn't have tripmeter in it only a odometer.
     
    Rideandrepair Thanks this.
  10. RocketScott

    RocketScott Medium Load Member

    562
    892
    Apr 10, 2013
    Kentucky
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    If it would work for you we can trade speedos. Mine is an '89, originally Canadian, so is in kilos. I don't drive it much so it doesn't matter to me. I have no idea if they are compatible. Just thought I should offer.
     
  11. special k

    special k Light Load Member

    89
    38
    Sep 6, 2008
    Ontario Canada
    0
    If you weren't 3000 miles away I'd be tempted la. I'll get this sorted out today or tomorrow. I have check on the tooth count and try the formula that was posted. It'll be a pain having it in miles and not having a tripmeter though. That's the price you pay for being too cheap to pay 500 bucks for a new one! la
     
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