help!!!
i'm new here and i just bought my first volvo. i love it, accept for my speedometer problem. i can not figure out why it is malfunctioning. the speedo reads about half of my actual speed. i have replaced the speedo itself, however it was out of a 740. i don't know if the difference in model matters. i have also replaced the speed sensor in the real axel. again i used a salvaged part, out of a 900 series. i also checked the wires and the appear to be getting power. speedo, wire, sensor......what else is there?!!!if anybody has any ideas please leave a comment. thanks.

Does the speedo function reliably otherwise? It's very important since you may just have a working speedo and a working speed sensor but the speedo is calibrated for different rear end ratio (or somesuch in effect).

1. What did the previous speedo do (before you replaced it). Was it dead? Were readings steady or intermittent? Whenever the reading would be there, was it correct or some percentage of the actual speed?

2. Does the replaced speedo do exactly the same thing as the one before replacement?

3. Does the trip meter work correctly? Find a stretch of highway with half-mile marks on it, or just use a decent map, gps if you have one or simply mapquest to figure how long a way it is before two strategically chosen intersections on a straight road nearby. Then just zero it at one point and read it after driving the distance you know from your chosen source.

Cheers, Kuba

kuba,
i will try the trip meter, i believe it is working properly. also, to answer your question, the first speedo did the same thing. however it also could have been a secondary choice. someyone told me today that if i did not have the sensor shimmed out properly it would not read correctly. what are your thoughts? thank you for your help.