Jump to content


Photo

VDO Tacho Issues


  • Please log in to reply
25 replies to this topic

#26 toryman76

toryman76

    Forum Fixture

  • Members
  • PipPipPipPipPip
  • 1,082 posts
  • Location:Melbourne, Vic
  • Joined: 16-January 06

Posted 18 July 2017 - 05:49 PM

I believe your problem is that the HEI puts out a low voltage pulse, where as your VDO tacho requires a full 12 volt square wave to function correctly.
 
You should install a "pull up resistor" to the pulse wire.
 
Connect a 1K ohm resistor from the 12 volt+ ignition switch wire to the tacho pulse wire.
 
This should fix your problem.


I tried resistors and they didn't seem to help. They made the tacho not move at all or very little. I'm keen to understand why it never worked so one rainy day I will sit down and check how its was mounted into the cluster...




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users