Speedometer and sender

#1
The VDO speedometer in my motorhome will read 15 mph when stopped and will read about 5-10 mph faster than my actual speed when underway. Does this sound like a bad speedometer, bad sender or both? If it is the sender, can someone tell me where it is located? The engine /transmission is a Cummins B5.9 coupled to an Allison MD3060.
The motorhome is a 1994 Gulfstream Scenic Cruiser.
Thanks
Jack
 
#2
Speedometer and sender

The sender should be in the tail shaft of the trans. It screws in and has a lock nut to hold it. With the speedo reading even when the bus is stoped and not runing it is probably the speedo head and not the sensor. The sensors are a common problem but will not make the speedo read when stoped. To prove this unplug the sensor and see what happens.
Good luck
Bill
 
Top