help - speedo stopped, hard shifts, flashing lights ...

camaroguru67 · Feb 7, 2016

Hey everyone I'm new to the forum and a new Diesel owner. Just got a 97 F250 7.3 and two days after I bought it the speedometer/odo just stopped working. The trans was shifting a little hard the day before and after the speedometer went out it shifts at odd times and shifts extremely hard. The overdrive light flashes and the 4x4 light is staying on. I got on and read a lot about this and everything points to the VSS vehicle speed sensor on the rear axle. I went to the parts place and bought a new one, it looked slightly different and was like a hard plastic with the magnet inside. Needless to say the $15 part didn't work. I returned it and called local ford dealership. They gave me what was said to be the ford recommended VSS .... it looked identical to the aftermarket one. Paid $40 for this one w/no return. Got home and installed it today and absolutely no change.

What do I do next? I've checked all fuses and none were blown. I cleaned the orig VSS and put it back in and no change ... What else could it be?

Really need you guy's help on this one. Spent all my money getting the truck and can't really afford to take it to a mechanic right now.

Whats my next step? Could it be something else?

mitch7.3 · Feb 8, 2016

Does the dome lights in the cab flash too? My 2000 did this to. Speedo would quit working, tow haul light on the shifter would flash if I opened the doors the dome light would flash. What ended up fixing mine was I had horrible battery connection. Cleaned them really well and put new bolts in and never had the problem again.

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6.0 Tech · Feb 8, 2016

Seen abs modules do this. Truck have abs?

Northwoods2002 · Feb 9, 2016

Typically OD light flashing with hard shifts means the trans is gone.

superduty4x4 · Feb 9, 2016

More than likely its the PSOM (programmable speedometer/odometer module) which is integral to the speedometer. Find yourself a used cluster from a 96-97 and swap that in to see if the problem goes away. If you can't find a 96-97 cluster you can use an older one but you'll have to disassemble it and swap everything into the white cluster "shell" from your truck, there are slight wiring differences among the years. Also note that since the PSOM stores the mileage info, whatever mileage the donor rig had will now show on your truck. I believe there are a few companies that can reprogram them.