Technical Erratic Speedo

[Alwaysared]

I've done a search but can't find anyone with the same problem as me, only non working speedo etc.
Anyhow I have a 2006 X244 2.8JTD Ducato and the as the title suggests the speedo is working along with the odometer but once the needle goes above 30mph it starts jumping up and down between 40mph and 70mph, the speedo has never been accurate and can be 10mph higher at a steady 60mph (measured using my satnav) which has never worried me but I have an after market cruise control and since this problem started it won't work, it gives an error tone that says it's detected a sudden increase or decrease in speed. Could it be the electronic sensor or the cable? Any help is greatly appreciated.

Regards,
Del

 

[Communicator]

I've done a search but can't find anyone with the same problem as me, only non working speedo etc.
Anyhow I have a 2006 X244 2.8JTD Ducato and the as the title suggests the speedo is working along with the odometer but once the needle goes above 30mph it starts jumping up and down between 40mph and 70mph, the speedo has never been accurate and can be 10mph higher at a steady 60mph (measured using my satnav) which has never worried me but I have an after market cruise control and since this problem started it won't work, it gives an error tone that says it's detected a sudden increase or decrease in speed. Could it be the electronic sensor or the cable? Any help is greatly appreciated.

Regards,
Del

I was thinking that another possible cause could be the instrument panel itself, but if your cruise control taps into the pulses to the ispeedometer, then this tends to point away from the instrument panel. A cable fault seems less likely than a sensor failure.

There is another possibility. The sensor is supplied via fuse F11, secondary services. F11 supplies several items , including the oil vapour heater iwhich can go short circuit, and kill the speedo indication. I am wondering whether something similar is happening to the sensor supply.

I also have a 2006 x244 2.8jtd, and given your problem, I think that I would start by changing the sensor. If undertaking this work, take care not to lose the fixing bolt which is M7, not a common size. It needs an 11mm spanner.

Attached below is a selection of annoted eLearn drawinngs, together with some of my own,

 

[Alwaysared]

Thank you for your reply @Communicator I'll look at those links and let you know how I get on

Regards,
Del

 

[FreeSpirit]

Hi
When the speedo on our X244 2.8JTD started jumping & reading OK one minute or either not working at all, I diagnosed it as a faulty transducer (speed sensor). They are available on ebay as well as Fiat dealers & that fixed it.
Reasonably easy to replace, - disconnect the wiring connector & remove the bolt holding the transducer, making sure you don't lose that & the thin washer.
Now comes the DANGEROUS part, with extreme caution lift the transducer straight up until the METAL pinion is clear of the hole. The pinion is only held in place by oil suction to the transducer assembly, so any bumps on the side of the gearbox or sudden movement whilst removing or replacing could cause it to drop into the diff assembly, there's also a thin steel washer between the metal pinion & the bottom of the transducer, so another thing to watch when removing & replacing the pinion.
If it does drop into the diff housing with luck you will need a strong magnetic pickup tool to get it out !!! ( if that happens don't forget to check that the washer didn't go with it)
Cheers