J Sweet: question on speedo sender

I found that the wires to the sender connector had been poorly repaired, and both had corroded through, breaking connection. But after repairing the connector, the speedometer still doesn't work. SO now I need to get to the connections at the back of the instrument cluster and check continuity through the sender circuit. I don't know anything about what a good sender is supposed to read...if it reads open, I will put a jumper in the sender connector and then I should read continuity if external wiring is good. Do you know of anyway to test the sender...perhaps it is supposed to read so many ohms static? No doubt in operation it is generating some type of pulses, maybe a scope is required. If the wiring to the sender checks out good all the way to speedo, then probably it is the speedo itself, I guess. A rebuilt one for my Mercedes was about $150....would it be about the same for Volvo?