Vito Speedometer Fault

[GTC]

Our Mercedes Vito has a very tempramental Speedo, The first time this problem had occured last november Our local Merc dealers replaced the Speedometer, it has since twice been put into a Mercedes Specialists, yet the problem still persists. The first time she went in, they said they could find no fault after road, and tacho roller testing, yet the second time it went in the speed readings were completely different at:

• 
  70mph the speedo reads 80mph,
  60mph > 52mph
  40mph > 33mph,
  20mph > 17mph
  10mph > 7mph

However when taking the van down for repair i was accompanied by another driver who advised to flash my hazard lights at 60mph so we could compare speeds, which i did, he was doing 65mph when i thought i was doing 60mph

 

[pascal]

Pretty sure it's an electronic speedo on the vito.

It sounds like speedo pointometer thingy may be faulty/sticky as the problem is not consistant. Usually speedos are set to go slightly slower than the speedo suggests.

Just one thing though, have you put different wheels/tyres than original?
What was the result of the second rolling road test?

 

[woodturner-fran]

Em.. it woudln't be a kilometers/miles thing? 40kph is approx 32mph and so on? (computer in dash set to wrong system)


Fran

 

[GTC]

The main dealers have said that they tried a Vito of there own, and the same same results were produced, so maybe the KPH/MPH settings could be wrong. :roll:

I'll keep you informed how this progresses. :?

 

[pascal]

I re-read your post.

You say when your doing 70 the speedo reads 80 (over-read)

And when you were doing 65 the speedo said 60 (under-read)

If it was a KPH reading, at true 62 the speedo would read 100
and at 31 the speedo would read 50.

If it is still covered under warranty, the dealer may want to fob you off, so they won't have to fit a new instrument panel

 

[SLinKyjoe]

altho the speedo may read over...the law is quite clear..they are not permitted to under read..ie, you have a road illegal vehicle if you are doing 65mph and the speedo says you are doing 60mph...

you really need to have this looked into quickly as now that you are aware of the fault, if you are stopped you, as the driver, are responsible for the roadworthyness of the vehicle you are driving.

 

[GTC]

If it is still covered under warranty, the dealer may want to fob you off, so they won't have to fit a new instrument panel

The speedo was replaced last November due to the same fault, but like i say the main dealers said they got the same readings from their own Vito (over read), and said that its perfectly fine. maybe their Tacho Rollers need calibrating ??