Dash speed error - 2008 Ducato 160 multijet

[sidi1000]

Hi All, anyone had same problem as this and point me in the direction of things to check.


Have a converted camper based on a ducato 160 multijet L4H2 and as a result it has a Altia digital tacho fitted. For some reason the dash speed has recently started to show a higher speed than actually being travelled at. If doing 60mph which is correctly shown on tacho and verified by gps speed the dash shows around 80mph!


From what I can find the gearbox speed sensor should go via ECU, output to Tacho then output from Tacho to dash. If logic wins over am I looking at it being the Tacho at fault or does dash speed actually come from wheel sensor and not from the tacho?


Under normal circumstance would not be a problem to live with but with this also meaning the mileage is out by some 25-30% its going significantly higher than it should if I don't get it fixed!

 

[s130]

Speedometer drives/signals come from one, either or both of the following:

o Final drive from the gearbox differential
o From the ABS / wheel sensors

Have you actually checked the odometer is reading incorrectly as well. Just because the speed in 20mph high it does not mean that the odometer/distance is similarly high.

Also if you can find someone with diagnostic kit near to you they can check what the various systems are reporting for vehicle speed.

 

[sidi1000]

Mileage is out by same % so it needs fixing ASAP as got some long trips over the next few weeks/months. Will see if diagnostic check comes back with anything.