Truck Repair: 1999 FORD F-350 diesel, odometer discrepancy, ford f 350

Question
hello i hope you can help my husband.The speedodemeter quits working but if he turns the key off and then back on while going down the road it will start working again but once he stops again it stops working. I hope you can help.

Answer
on this ford you have a speed sensor on the rear end of the transmission drivers side near where the output shaft exits the trans. this sensor is really a small genarator, the faster you go the more power it puts out and inturn it transmitis a signal to the speedo. this sensor is only held in with 1,10 mm bolt and will pull right out its about 35.00 dollars to replace from autozone or pepboys,they can test this sensor there but since its working partime it will prob. check ok i would still replace this sensor.also i would stay away from the dealer on this because they use carfax and this would report as a odometer discrepancy and could hurt a trade in value.if you need more help on this please ask... and thank you for your question.