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Herky jerky

I have a 1995 E-350 with a 7.2 diesel. On our way south through Alabama (Auburn) we stopped for fuel and when back on the highway, it became evident that something was awry, in that the transmission would downshift unpredictably.

When I turned off the overdrive, the lighted ‘OFF’ would flash, and there would be no change in the pattern.

We returned to NC mountains in this condition (fun drive!)where I took it to my mechanic who replaced the speed sensor. He demonstrated the relative weakness of the magnet in the old one, but unfortunately the new speed sensor exacerbated the symptoms. Presently, if I turn off the overdrive, the downshifting is minimized.

Other symptoms are that the speedometer gyrates wildly and the odometer registers ~20% of mileage travelled.

Any ideas? Thnaks, Leo

OH, just wondering, with all the repair questions you must get, how do you find time to get any work done?

Best to you!

The Vehicle Speed Sensor sends its signel to the Programable Speedometer/Odometer Module which processes and passes the signel to the PCM. Since your speedometer and odometer are acting up, the problem could be in the wiring to the PSOM module or in the PSOM module itself.

BTW Tom and Ray don’t provide answers on this site. Many helpful lurkers pipe in their opinions as they have spare time to cruise the site and see interesting posts to which their knowledge and experience can provide helpful hints.

Hope this helps.

…hope it helps too…thanks for the lead and info!