Slightly dodgy second hander - speedo fault

[marrow85]

Just bought a 406 estate lx vreg. The milage has been change and reads 208k and the speedo drops to zero and bounces back now and again, jolting the car seems to fix as does stopping and poking about under the bonnet at random wires, or just leaving it for a few miles. Anyone got any more methods for finding and repairing the fault?

Also pops out of first gear sometimes when pulling away do you think this means the whole gear box needs replacing? everything else seems good.

[omega]

petrol or diesel

[marrow85]

Petrol

[Harshan]

Speedo issue can be a loosen connector where speed sensor connects to loom via a three pin connector. If not this is a typical sign of a failed speed sensor.

About gear issue, is it only the first gear or both first and second? Could be synchronizer unit for 1st and 2nd gear.

[ally406]

The speedo drive sensor is located on the gearbox differential. Disconnect the plug from it, give it a squirt with WD40, and connect and disconnect it a bunch times to clean the contacts. Try that first, solved exactly the same issue for me on a petrol 406.

[marrow85]

Thanks guys, haven't noticed 2nd gear playing up, as long as I hold it in when I start to move it stays in fine from then on. Where exactly should I look for a gearbox diff?

[Harshan]

Thanks guys, haven't noticed 2nd gear playing up, as long as I hold it in when I start to move it stays in fine from then on. Where exactly should I look for a gearbox diff?

if it's D8, worth looking at gear links, a simple adjustment might be able to sort it out, if the issue is due to not engaging the gear properly.

[marrow85]

Don't think its a D8 - new car and all - read up on gear linkages though and could be that, the gear stick has to be way forward to engage 1st, so far your hand knocks the dash. Got some WD40 so off to find the connectors!

[Harshan]

Don't think its a D8 - new car and all - read up on gear linkages though and could be that, the gear stick has to be way forward to engage 1st, so far your hand knocks the dash. Got some WD40 so off to find the connectors!

if it's way forward, I assume there's a bit of a free play. If it's D9, then it's gear cables to check

[steve_earwig]

Are 3rd & 5th the same? If it's just 1st I'd suspect a bent selector fork

Do you notice a drop off in performance when the speedo drops? If it does nothing it could be a joint on the back of the instrument panel. If it does suspect the transponder connection or the transponder itself.

[marrow85]

No third and 5th are fine, still not been our to drive it but had a good poke and squirt yesterday. I noticed that their was a rod on the right hand side of the engion, coming from the middle, roughly where the gear stick is, running to the side of the engion - where I presume the gear box is located, it attaches to a lever type thing and has a plastic bit on the end where they join. Odd description I know but this appears to be held together by some rather well placed cable ties. Any idea what this is and what it does?