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Howdya recalibrate your electric speedo?

Discussion in 'The Garage' started by angrysnowplow, Jul 31, 2003.

  1. angrysnowplow

    angrysnowplow 1/2 ton status

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    Can't find much info on this...Anyone know how to correct an electric speedometer in a 90 K5 with a NP241?
     
  2. K5BLT4FUN

    K5BLT4FUN 1/2 ton status Premium Member

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    I had a 91 Suburban with a 241. The 241 has a electronic pulse generator in it. This signal is sent from the 241 to a device called a Vehicle Speed Sensor (VSS) buffer. You can order a new VSS buffer through your GM dealer. You will just have to tell them what your gear ratio is and the true diameter of your tire while on the truck. It cost me $100.00, but it works great.
     
  3. angrysnowplow

    angrysnowplow 1/2 ton status

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    Thank you sir! /forums/images/graemlins/thumb.gif
     
  4. K5BLT4FUN

    K5BLT4FUN 1/2 ton status Premium Member

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    No problem. Let me know what gear ratio and tire size I may have the one you need. I went through several differnt tire and gear combinations while I owned my Sub.
     
  5. K5 NUTT

    K5 NUTT 1/2 ton status

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    Parts are NOT serviceable thru GM anymore...

    Call Instrument Sales And Service...info they will need..

    1) Gear Ratio
    2) Tire Circumfrance..make a mark on the tire and let it roll one revolution...measure and record...cal ISS with this info and they will burn a new calibrated drac for you. Drac (Digital Ratio Adapter Controller). You might ask if they can burn your current drac... located directly under the radio....

    DW
     
  6. K5BLT4FUN

    K5BLT4FUN 1/2 ton status Premium Member

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    K5 NUTT, Thanks for the correction on the name. I alway referred to it as a VSS, but after digging last night you are correct. It is called a DRAC.
     
  7. K5BLT4FUN

    K5BLT4FUN 1/2 ton status Premium Member

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    I looked last night and I have two DRAC's from my old Sub. One is for 3.73 gears with 35" Tires and one is for 4.11 gears and 35" tires.
     
  8. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    Any idea on the cost?

    Great info guys!! /forums/images/graemlins/thumb.gif
     
  9. angrysnowplow

    angrysnowplow 1/2 ton status

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    I currently have 3.73's and 35's, but my 4.56 axles are going in soon. Thanks anyway.
     
  10. K5BLT4FUN

    K5BLT4FUN 1/2 ton status Premium Member

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    No problem. Hopefully this info helps.
     
  11. 79Silv4x4

    79Silv4x4 Registered Member

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    Does anyone have a phone number or email for Instrument Sales & Service?
    Thanks
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    If this is for the same thing, search for my "end all DRAC VSS" post I made not too long ago. You can fix it yourself for nothing.
     

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