VS speedo jumps from 0 to 40

[jeepster]

I bought a VS V6 auto, and when accelerating from rest, the speedometer sits at zero, then jumps to
40 km/h. This seems to coincide with a gear shift. But when decelerating, the needle shows speeds
below 40 okay. Now my grandad has a VS and it started doing the same thing a few years back.
He drives pretty gently, not a leadfoot like me. So I thought this must be common fault. I searched
a bit, but most threads refer to totally dead speedometer.
Any ideas what causes this jerking?

[sleepa]

My girlfriends last 2 cars has this problem. The old car needed the speedo cable to be greased and retightened, but the new one is electronic and I have figured that out yet. Could be terminals need cleaning or something, electrical short?

[jay_wr8]

my last 2 VS's did this to, i wouldn't stress to much about it, not many places in echuca with under 40 zones are there?

[Brett_jjj]

It might be something to do with the speed sensor,or a bad connection like dry/broken solder on the circuit board at the back of the cluster.

[jay_wr8]

i always thought the needle just needed a clean and lube, prob best to pull the cluster out and inspect if your worried about it, does it do it every time or just sometimes? most probably a sensor if it doesn't read anything under 40

[88GreenVN]

As said above the speed sensor may be on the way out. The voltage regulator may have a cracked solder joint. If the PCB on the back of the cluster was briken - it would fail completly.

I dont think you can "lube" the speedo as such.

[pillzor]

mine sometimes does this sometimes but a gentle tap on the steering wheel kicks it into action.

[jeepster]

I tried the turning speed alert into a digital speedo trick, and it shows correct speed while the analogue speedo is still asleep.
Also the trip odomoter does not move until the needle jumps up. I guess that the speed sensor is okay and the fault lies
into the instrument cluster.