speedo repair info

[1979jimmy350]

Does anyone know of where i can find info on fixing a electronic speedo for my k-5. When i start moving the needle jumps to 85 mph then goes to zero and once in a while decides to move. I know the sensor is working becasue i get the correct speed from the data link connector so i know the problem is in the speedo head

thanks

 

[sweetk30]

might be the drac is going bad ? i dont know for sure. but thats the busser convorsion unit from signal to speedo head.

i have extras that are modifyed with dip switches for custom gear/tire combos for correct speedo read out.

mabye 4x4high scott will post up. he has been working on the electric speedo system with his custom dash. he might know more.

and here is a good place i hear of for cluster work. http://tachman.com/

 

[1979jimmy350]

might be the drac is going bad ? i dont know for sure. but thats the busser convorsion unit from signal to speedo head.

i have extras that are modifyed with dip switches for custom gear/tire combos for correct speedo read out.

mabye 4x4high scott will post up. he has been working on the electric speedo system with his custom dash. he might know more.

and here is a good place i hear of for cluster work. http://tachman.com/

Thanks for the link, I dont have a DRAC so i know that's not the issue, I am running a LSx so my vss signal goes to the pcm then i am able to specify the digital output for the speedo and i have that correctly set to 4000 digital pulse per mile

 

[sweetk30]

o.k. then i have no clue sorry.