Nissan Repair: 2000 Nissan Frontier will drive FORWARD in Reverse, vehicle speed sensor, nissan frontier

Question
So that would cause it not to have a reverse gear? The car is not on the road so I can't bring it to get diagnosed.  I heard it is not safe to "flat tow" it. Could the speed sensor control have anything to do with it? Thanks for the help?
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-----Question-----
The truck is going forward in all gears, there is no reverse at all.  It also seems to start on a high gear, possibly 2nd or 3rd gear.  Automatic transmission.  The linkage appears fine, cables move.  Any help please!!!
-----Answer-----
Teresa,

The transmission is probably locked in third gear as this is a self protection feature of the transmission.  There is something wrong with the valvebody and the computer for the transmission has stored codes and has also locked the tranmission in this mode.  Take it to Cottman Transmissions and have them read the code.  They would be much cheaper than the dealer.  If you have a good speciality Nissan shop that would do to.  The thing is someone needs the computer to read the transmission code to tell what all is wrong with the transmission.

Answer
Teresa,

If you have a two wheel drive you could get it towed form the back.  If it is four wheel drive and you can put the transfer case in neutral you could tow it too.  But, if it will drive in forward why not take it down.  No, the speed sensor would not have anything to do with reverse.  But, if it was out the speedometer and odometer would be messing up.  The computer gets the speed of the vehicle at the speedometer head unit from the signal it receives from the vehicle speed sensor that is located on the transmission.