300tdi Speedometer / Transducer

A few weeks ago the speedo cable failed so it was replaced ('97 300tdi defender). But with the new replacement it seems to bounce quite wildly up to 40'ish then works fine.

Since then I've got a clicking sound behind the dash of our '97 300tdi Defender. It seems speed related and I think it's the speedometer needle bouncing in the dial - I've also do a lot of rough corrugated tracks abroad recently so could just be something loose in the dash.

I've been told that it might be the transducer (?), never even heard of one of those - can anybody point me in the right direction of what it is, where its located, how easy it is to change etc.


































































I had the speedometer cable replaced a few weeks ago

The square bit of cable might not be inserted into the speedo head far enough which might be why it’s jumping and clicking

Are you sure the cable is fitted correctly into the back of the dash?
A few drops of oil down the cable might help as well.

The speedometer on a 300tdi is cable driven.
In the transfer box, behind the handbrake drum there is a plastic wheel, engaged with a cog that spins a pin which has a square hole in the middle.
The square cable that it spins fits into a square hole at the back of the speedo.

The cable spins and the speedo displays a speed.
On the newer Defenders (TD5 etc) the speedo is all electric and instead of a square cable there is a transducer that sits in the square holed pin (same place, behind the handbrake drum) and produces a voltage which is fed to the speedo.

The square cable can be easily dislodged and not sit in the square holes correctly causing it to jump and click and send the needle bouncing around.
Take it back to the person who fitted the new speedo cable - it's not right.