Still having speedo issues... Interfereance?
Thread Starter
TECH Regular
Joined: May 2005
Posts: 406
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From: Bay Area, CA
Still having speedo issues... Interfereance? Well, decided I would try to tackle my speedometer issue again today. Some of you may remember my frustration from a few months ago. Basically, at idle or driving below 10MPH the speedo acts erratically, bouncing between 140-160MPH, and then corrects itself at speeds above 10MPH. Today I discovered that if I shut the engine off while driving, and leave the ignition on, the speedo reads correctly even at speeds below 10MPH, perfectly smooth as it should be. So, that leads me to the possibility of something creating harmful interfereance while the engine is running. What could do this? Crank position sensor? Coils? Ive swapped wires with the Z06, so I don't think its bad wires. Sure wish I could get this solved... 
Thread Starter
TECH Regular
Joined: May 2005
Posts: 406
Likes: 0
From: Bay Area, CA
Originally Posted by LS1MCSS
My kind of speedo are you using and does it get the signal from the VSS or the PCM?
If I tap into the VSS high wire to get my signal, the speedo will work at all speeds but the transmission will not shift. If I use the PCM signal (pin 50) the speedo only works above 10MPH, but the car drives perfectly. Below 10MPH it bounces between 140MPH and 160.
