VP Calais Speedo Problem

[Duph83]

Hey All.. I have a 1994 VP Calais (supercharged V6 (3.8ltr.)) ... My Problem with the speedo is as follows...


When I am Driving above 90km/h, the speedo will drop to 0, then jump back up to the speed I am doing, then wait a second, drop back to 0 then back to my speed, wait a second, then do it again.. and it keeps doing it.. Now it only Does it if I am accelerating (above 90km/h don't forget).. but if I take my foot off and let it roll.. it will stay at the speed.. however if I accelerate hard (foot to the floor) the speedo wwill climb as per normal until I back off to a normal rate of acceleration, but once again, if I don't accelerate at all it will work normally while I just roll.. I have replaced the Speed Sensor in the back of the gear box (Turbo 700). Holden have also pluged their computer into mine, and gone for a drive with me.. and the computer is recieving the same signal, of which I am seeing displayed on my Speedo.

They say that the speed sensor goes into my computer, then computer to the speedo. Has anyone has this problem with their VP .. or know of a way to fix this problem? I cant use my cruise control above 90 becuase the car believe's I'm always stopping, and my trip computer (distance travelled) gets thrown out because it thinks I'm not travelling at a constant speed. Plus it's damn annoying.

can Anyone offer some advice? Cheers..

Ben