Volvo: volvo 740GL, ohm meter, rear axle

Question
my boss has this 1989 volvo and a couple weeks ago the speedometer stop working, the car drives good but he cdoes not know how fast is going.how can we fix this problem?

Answer
Raul,
Look at the sensor in the cover plate of the rear axle to make sure that the wires are not broken at the connector.
Second pull out the clusster and identify the wires to the speedo using an ohm meter make sure they are good.
Third take the cluster to a speedo shop to have it tested.