speedometer stops working

[bestacinc@aol.com]

I have a problem with my 99 F350 160,000 miles 7.3. sometimes the speed odomer stops working, and the over drive light blinks (although still in overdrive). when i turn off and restart all is ok again. any suggestions ? is it just time to replace the gauge cluster?

[NBhunter80]

fuse dying?

[fulltimer50]

When I had problems with my speedo and ABS lite coming on I replaced the VSS sensor in the rear. I dont think that sensor will cause tranny problems though.

[bestacinc@aol.com]

thanks. the fuse checks good. i don't think a fuse can be going bad, either open or not. but i'll change it anyway.

[bestacinc@aol.com]

thanks, i'll change the sensor. not having trans (overdrive problem), just the light blinking when the speedo stops working

[fulltimer50]

The blinking lite IS an indication for a tranny problem. I would wait for more informed input before changing parts.

[bestacinc@aol.com]

thanks again. good suggestion. had the trans rebuilt apx 55,000 ago. took it in to trans shop and had it checked. other then time to service, which was done, everything else checked out ok. truck has a program - i plan on clearing out the program and reinstalling next. this speedo problem has happened 3 times in the last 2 mouths. always fixes itself when i turn off the key then restart.

[Tallavana]

My speedometer quits around 110 but comes back if I slow down below that.

[JerryKing]

I just went through this. The overdrive OFF light will flash if you have lost the VSS signal from the differential speed sensor. The signal goes from the differential to your ABS module, and from there to the PCM, speedo, trip computer, and cruise control. When your speedo isn't working, check to see if your mileage computer and cruise control are working. If not, you have no VSS signal (and no rear ABS). The differential speed sensor is cheap and easy to replace. A much less likely cause (and much more expensive) is the ABS module/controller.

[bestacinc@aol.com]

The problem went away. I dumped the proformance program, reinstalled original, then reinstalled program. Did this about 6 weeks ago and have had no more problem. Fixed??

[action4478]

Originally Posted by bestacinc@aol.com

I have a problem with my 99 F350 160,000 miles 7.3. sometimes the speed odomer stops working, and the over drive light blinks (although still in overdrive). when i turn off and restart all is ok again. any suggestions ? is it just time to replace the gauge cluster?

As said ,,VSS ,,I had the same symptoms ,,It was a bad wire from the frame to the VSS ,,make sure there is a good ,clean connection,,,Mine happened primarily hitting bumps in the road...

[JerryKing]

Originally Posted by bestacinc@aol.com

The problem went away. I dumped the proformance program, reinstalled original, then reinstalled program. Did this about 6 weeks ago and have had no more problem. Fixed??

I doubt it. I don't see how your performance program would affect the VSS signal going to the speedometer, unless it is making changes to the ABS module programming as well as the PCM. Since your problem is intermittent, it may be a wiring issue. If it happens again, I'd carefully check the differential speed sensor connector and the wiring harness from there to the ABS module. If you don't find any problems, I'd go ahead and replace the speed sensor, as it is only about $30. Good luck!

[bestacinc@aol.com]

Thanks 2 all