speedo problem

Help! I have a 940 with an electronic(?) speedometer which is spasmodic.
Sometimes it will only go to 78kmph. other times it works, sometimes the
hand doesn't move at all. and today it is showing 118 standing still with
the ign. on with or without the engine running.
Could you please give me information to where I should start to look for the
problem. Could it be a sender or the speedo?. Where is the sender?, Who
would be able to remove the dash to take the speedo out to have it repaired,
if that was the problem?.
Any help would be greatly appreciated.

 

Check on the rear end/differential.

Looked at from the rear, should be on left upper side of pumpkin.

 

The sensor wiring is shared with the ABS (for rear wheels). Your problem
could well be due to the connector on the rear of the instrument panel
having worked loose or similar caused by the speedo sensor input plug (four
pin with plastic clamp).

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).