1996 Town Car Speedometer Issue wont display speed all the time

[lincolnjlincoln2]

Ok so here is the problem, I have had this car for about 2 years now and have had problems with the digital speedometer from the begining. It started out as an annoyance eg, dropping to zero for a brief moment while driving on the highway but then going back to the propper speed. It has gotten progressevly worse over time now to the point that it displays 0 more often than the speed this is in town and on the highway. now i would like to point out a few things that i have noticed number 1, even when the speedometer hits 0 the speed control continues to hold the set speed an in fact can be set, number 2, the odometer also stops when the speedometer does, 3, as expected the instant economy drops to 0, 4, another thing i have noticed is that somtimes my controls for the computer dont work left, right, e/m button.
One thing i would like to point out is that if I hit a bump it can effect the system eg, if the speedometer is working it could cause it to stop or if it isnt it could case it to start working. at first i thought this would be as simple as a new speed sensor but now im thinking a gauge cluster set or even possibly a short but thats why im asking anyone who may have had a simmilar experience. any help would be appreciated.

With Reguards
Lincolnjlincoln2

 

[97Towncar-4R70W]

Digital Speedometer

Ok so here is the problem, I have had this car for about 2 years now and have had problems with the digital speedometer from the begining. It started out as an annoyance eg, dropping to zero for a brief moment while driving on the highway but then going back to the propper speed. It has gotten progressevly worse over time now to the point that it displays 0 more often than the speed this is in town and on the highway. now i would like to point out a few things that i have noticed number 1, even when the speedometer hits 0 the speed control continues to hold the set speed an in fact can be set, number 2, the odometer also stops when the speedometer does, 3, as expected the instant economy drops to 0, 4, another thing i have noticed is that somtimes my controls for the computer dont work left, right, e/m button.
One thing i would like to point out is that if I hit a bump it can effect the system eg, if the speedometer is working it could cause it to stop or if it isnt it could case it to start working. at first i thought this would be as simple as a new speed sensor but now im thinking a gauge cluster set or even possibly a short but thats why im asking anyone who may have had a simmilar experience. any help would be appreciated.

With Reguards
Lincolnjlincoln2

I have no prior bad experience with VSS, but I suggest you first check your VIN # for Cruise Control problems that Ford was having affecting many of their cars product lines, including Lincolns.... . Then look for any stored Fault Codes? as you know, a VSS is a magnetic pickup that sends a signal to the microprocessor assy. The VSS signal tells the microprocessor assy the vehicle Speed and controls it to modify the upshift schedules. While the OSS (output Shaft Speed Sensor) is used to control converter clutch, and also used in determining EPC pressure on shift scheduling: causing no converter engagements, harsh shift and/or abnormal shift schedules.. This info is per ATSG.
I would also pull out the VSS (see photo) and check the VSS sensor gear for wear and condition. ? The gears are made of some kind of hard plastic and eventually they wear out or brake a teeth or more that may cause it to jump or not engage properly with the rotating output shaft until it stops turning for lack of contact due to wear or broken teeths. . . Gears are colored coded per application. Mine have 19 teeth that contacts and runs on the 8 steel teeth grooves of the output shaft and is beige in color. You can obtain the VSS gear separate as spare part from a dealer..to match your application: model car, year, transmission, rear axle ratio, tires, etc..
You may also like to check the internal resistor values of the VSS at sensor contact test pins with the specs for your application. If OK, recheck your wiring for continuity to the further next connector, etc..thus you may have a poor or bad connection that is causing the intermitency that you describe.
Hope this info helps.