Chrysler Repair: 96 van speedometer doesnt work, electronic failure, cv joint

Question
i read your response to a question about the speedometer on a grand caravan, my vans speedometer is not working, and was wondering if you had anymore insight into what the cause could be. we recently replaced the cv joint, and now the speedometer is not working, i checked the gear that the speed sensor plugged into and it looked fine, i replaced the speed sensor, and it still is not working, i was wondering if you had any additional information on the subject that could help. thank you

Answer
Hi David,
If the trans is shifting normally that would indicate to me that the sensor and its wiring to the trans controller is OK. Aside from an electronic failure of the speedo head unit itself, the other possibility is that the needle for the dial is wedged on the wrong side of the pin at the "0" on the dial. When that happens of course it won't move. There is a simple fix that might work if that were the case: with the ignition 'off', press the trip and reset buttons and hold them, then turn the ignition 'on', then keep holding until the word "code" appears in the odo window, then release the buttons and the cluster will go through a set of calibrations and checks which will move the needle to the other side of the pin. The checks are over when '999' appears in the window, but then some other tests will run.
See if that corrects the speedo function. If not, then because the data to run the speedo comes into the cluster with many other data streams on a single pair of wires, and those others seem to be working, the only other possiblity I believe is that the speedo head in bad.
Roland