GM Inside - Muscle Cars - Jeep

Support FSC and see no ads! - Click Here
Results 1 to 5 of 5

Vss Buffer

This is a discussion on Vss Buffer within the Technical / Maintenance forums, part of the General Discussion category; I have a Z71 1994 5.7L., and the speedometer is not working. The PC diagnostic indicates a VSS 024 failure, ...

  1. #1
    Registered User
    Join Date
    Sep 2005
    Location
    Central America
    Age
    43
    Posts
    9

    Question Vss Buffer


    Support FSC and see no ads! - Click Here
    I have a Z71 1994 5.7L., and the speedometer is not working. The PC diagnostic indicates a VSS 024 failure, and, after a slow check, we detected the failure in the VSS buffer. The chevy dealer, canīt find this part, they said they donīt have it. Does anybody know, where can I find the VSS buffer ?? And, whatīs wrong with the engine, if this electronic card is dead ??

  2. #2
    Loves GMT400 haters someotherguy's Avatar
    Join Date
    Aug 2005
    Location
    somewhere else
    Posts
    11,099

    Re: Vss Buffer

    That's your DRAC, and it'll be located behind the glovebox in the same area as the ECM. It's a small circuit board that is cased in plastic. You can get them from the junkyard all day long out of other trucks for next to nothing; maybe $25 max. The trick is picking one that comes from a similar truck as yours with hopefully the same transmission and rear end (check the RPO codes in the glovebox) - the DRAC is "adjustable" for the differences and with the wrong settings your speedo will read incorrectly. There's a tech article here on FSC that describes modifying the DRAC with a dip switch to make it easier to adjust, as the factory used jumpers that have to be soldered/cut/etc. to make changes.

    Also don't rule out the sensor in the transmission tailshaft.

    Richard

  3. #3
    loves Mickie James oldred95's Avatar
    Join Date
    Mar 2004
    Location
    Kiowa, KS
    Age
    26
    Posts
    11,561

    Re: Vss Buffer

    Quote Originally Posted by Z71SSilverado
    I have a Z71 1994 5.7L., and the speedometer is not working. The PC diagnostic indicates a VSS 024 failure, and, after a slow check, we detected the failure in the VSS buffer. The chevy dealer, canīt find this part, they said they donīt have it. Does anybody know, where can I find the VSS buffer ?? And, whatīs wrong with the engine, if this electronic card is dead ??
    Your truck has a VSS, its located under the trucks ECM (computer) which is located behind the glovebox. You will have to take the glovebox insert out to get to it. If its fried then yea that will make your speedometer stop working. GM is full of crap if they can't find it. Actually its called a VSSB. Vehicle Speed Sensor Buffer. Maybe this will help you out a little.
    1995 Silverado - ported vortec heads, 4L80E, efans, LT4 Hot Cam, Rear disc brake conversion w/drilled and slotted rotors
    1999 NBS Silverdo - transgo HD2 shift kit, 3 inch dynomax ultra flow, Ford keys and 305/70-16 Mickey ATZs

  4. #4
    loves Mickie James oldred95's Avatar
    Join Date
    Mar 2004
    Location
    Kiowa, KS
    Age
    26
    Posts
    11,561

    Re: Vss Buffer

    Quote Originally Posted by someotherguy
    That's your DRAC, and it'll be located behind the glovebox in the same area as the ECM. It's a small circuit board that is cased in plastic. You can get them from the junkyard all day long out of other trucks for next to nothing; maybe $25 max. The trick is picking one that comes from a similar truck as yours with hopefully the same transmission and rear end (check the RPO codes in the glovebox) - the DRAC is "adjustable" for the differences and with the wrong settings your speedo will read incorrectly. There's a tech article here on FSC that describes modifying the DRAC with a dip switch to make it easier to adjust, as the factory used jumpers that have to be soldered/cut/etc. to make changes.

    Also don't rule out the sensor in the transmission tailshaft.

    Richard
    On the trucks equipped with a 4L60E transmission its called a VSSB (93-95s and some late 92s use the 4L60E). Yes it is easiest to find a truck with the same rear axle ratio but its not manditory like you said. And switching jumpers around to make the speedometer read right is really pretty simple. I corrected my speedometer reading this way and it took about 30 minutes from start to finish.
    Last edited by oldred95; 09-25-2005 at 03:40 PM.
    1995 Silverado - ported vortec heads, 4L80E, efans, LT4 Hot Cam, Rear disc brake conversion w/drilled and slotted rotors
    1999 NBS Silverdo - transgo HD2 shift kit, 3 inch dynomax ultra flow, Ford keys and 305/70-16 Mickey ATZs

  5. #5
    Registered User
    Join Date
    Sep 2005
    Location
    Central America
    Age
    43
    Posts
    9

    Re: Vss Buffer

    Thanks, I solved my problem. I replaced the drac, now my truck is the same again.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •