crazy speedo

[Musogen]

Speedo is going crazy, all over the dial whether the vehicle is moving or not (but only with engine running)! Sometimes rests on zero for a while, sometimes even shows the correct speed for a while, then goes crazy again. Have just replaced the display with the same Ford part code and it behaves the same way. On VCDS lite the engine, central electrics and instruments controllers all show the same erratic pattern as the speedo.

Engine gives fault 17948 P1540 35-10 vehicle speed signal: signal too high
Instruments gives fault 01086 speedometer/6-10 vehicle speed sensor (G22)

Does all that sound like the VSS or dodgy wiring/connections?
If VSS does anyone have a part number, and how easy is it to change (for a musician with delicate hands!)

2002 1.9 TDI Zetec 6 speed manual

[insanitybeard]

It may be worth trying to get to the speed sensor if you can and disconnect it and see if the speedo drops to zero and stays there, if it's still misbehaving it could be a wiring short or earthing problem. I'm not exactly sure where the sensor sits on the gearbox I'm afraid but I think it has been mentioned previously that it's in the vicinity of the driveshafts where they emerge from the gearbox.

[Musogen]

Good thinking, will try later...
Thanks

[insanitybeard]

Ok, the speed sensor is number 22 on this parts diagram so it is on the rear of the gearbox on the 6 speed manual, on the engine side (closest to the offside drive shaft) by the looks of it.

[Musogen]

Thanks for help (6 months ago!). It was the speed sensor - when we found it it was broken on top. Eventually persuaded to come out, new one fitted and all is tickety boo!