Technical Speedo not working.

[Jayen4]

Hey all ! .....

Does anyone know how the speedo is driven on a '06 Doblo 1.9 , please ?? Is it from a mechanical or electronic unit on the gearbox or is it driven from a wheel sensor ? Anyone with specific knowledge on this please ?? Need to get it sorted....

 

[bugsymike]

Hey all ! .....

Does anyone know how the speedo is driven on a '06 Doblo 1.9 , please ?? Is it from a mechanical or electronic unit on the gearbox or is it driven from a wheel sensor ? Anyone with specific knowledge on this please ?? Need to get it sorted....

I think you will find it is from a electrical unit in the same place on the top of gearbox diff assembly area. Black plastic unit left front of this photo.

 

[Jayen4]

I think you will find it is from a electrical unit in the same place on the top of gearbox diff assembly area. Black plastic unit left front of this photo.

Thanks for that Bugsy..... I shall have a look . I'm not sure whether it's this unit or a broken wire , as I've just found broken wiring elsewhere on the car ( that controls other things ). .... Just as an aside...would the 'sender' unit be unique to the Doblo or could it be found on such as a Punto with the same engine ??

 

[bugsymike]

Thanks for that Bugsy..... I shall have a look . I'm not sure whether it's this unit or a broken wire , as I've just found broken wiring elsewhere on the car ( that controls other things ). .... Just as an aside...would the 'sender' unit be unique to the Doblo or could it be found on such as a Punto with the same engine ??

I would only be guessing, but assuming similar age 1.9 engine hopefully.
A lot of people on here swear by ePer details to identify parts so might be worth checking there.

 

[Jayen4]

Ok Update on this issue...... Today my local mechanic took out the the small electrical plug unit ( the one that Bugsy showed in the pic above ) and tried to test it for continuity.....couldn't get any readings from it . ( Apparently it should show either 12v or 5v , but getting nothing . ) . Have ordered a new one from the local factors . .... The other more concerning thing is that he thinks that the plastic drive gear , just inside the gearbox casing is worn out or chewed up ! Can that specific part be changed out / replaced , without having to remove and strip the gearbox ?? ....... Alternatively , does anyone on here have a suitable gearbox ( M88) to sell or even maybe a broken gearbox , that might have the speedo drive parts that I could use ??

 

[bugsymike]

Ok Update on this issue...... Today my local mechanic took out the the small electrical plug unit ( the one that Bugsy showed in the pic above ) and tried to test it for continuity.....couldn't get any readings from it . ( Apparently it should show either 12v or 5v , but getting nothing . ) . Have ordered a new one from the local factors . .... The other more concerning thing is that he thinks that the plastic drive gear , just inside the gearbox casing is worn out or chewed up ! Can that specific part be changed out / replaced , without having to remove and strip the gearbox ?? ....... Alternatively , does anyone on here have a suitable gearbox ( M88) to sell or even maybe a broken gearbox , that might have the speedo drive parts that I could use ??

That might be more of an issue if the problem is the drive on the diff gear assembly, normally they do not give a problem as nylon gears driving a very light load of the speedo sensor.
So unless speedo drive was forced in wrong in the past at an angle causing damage, in my mind the only other cause can be wear in the diff gear bearings causing slop so the plastic gears don't mesh properly.
I seem to recall early FWD Ford Escorts had a problem with that as they got older.

 

[Jayen4]

That might be more of an issue if the problem is the drive on the diff gear assembly, normally they do not give a problem as nylon gears driving a very light load of the speedo sensor.
So unless speedo drive was forced in wrong in the past at an angle causing damage, in my mind the only other cause can be wear in the diff gear bearings causing slop so the plastic gears don't mesh properly.
I seem to recall early FWD Ford Escorts had a problem with that as they got older.

Thanks for the reply !..... Hmmm..... I don't think that there's anything wrong with the diff gear bearings....Gearbox changes gears smoothly and no noises or vibrations from that department . I have ordered a new sensor plug/assembly....that is supposed to be here on tuesday , so I'll get that fitted and hopefully that will be the problem sorted . If that doesn't fix it , then I'm in trouble ! I will report back after I've got this sensor fitted .....

 

[bugsymike]

Thanks for the reply !..... Hmmm..... I don't think that there's anything wrong with the diff gear bearings....Gearbox changes gears smoothly and no noises or vibrations from that department . I have ordered a new sensor plug/assembly....that is supposed to be here on tuesday , so I'll get that fitted and hopefully that will be the problem sorted . If that doesn't fix it , then I'm in trouble ! I will report back after I've got this sensor fitted .....

The quick test is where the output drive shaft comes from the diff near the speedo drive , is see if excessive play up and down at that point.

 

[Jayen4]

The quick test is where the output drive shaft comes from the diff near the speedo drive , is see if excessive play up and down at that point.

I take it that you mean excessive play in the little shaft that connects to the sensor plug/assy ?? I shall check that before the new sensor unit is offered up..... Thanks for your help .