Just a little aside here;
if you think that it may be the little transducer box that lives in the trunk; get one now, They are kind of like Rocking Horse Poop and Virgin's Tears.
Pretty much NLA.
Anywhere.

 

Tried a known working interface unit........still nothing from the speedo.

I give up!

 

Have you swapped in a known working speedo head?

 

Not yet. Need to find one first.......

 

Loads on ebay. or Andy Harvey at Just XJS for instance. The speedo is not a mystery, it just needs a signal from the gearbox/diff (depending upon model year) a good wire and a good head unit with a functioning PCB track and multiplug. Despair not!

 

OK, Andy at Just XJS is finding me a cluster, so fingers crossed!

Thanks for the tip, Greg.

 

is the pulse per mile on the pre diff speedo cars the same as the ppm on the later cars. IIRC the ppm on cars with diff mounted speedo was 8000.