Speedometer doesn't work..

tmisch

New Member
Feb 24, 2011
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Hello, I recently bought a 1997 Mustang GT, the speedometer doesn't work and when I am doing about 50mph it says i am pegged on the dash, so i called around and looked on forums to see how to fix... answer I found was Transmission Speed Sensor... looked everywhere and were all wrong part, removed the one in the car and called a local Ford dealership, gave the part number and it comes back as a 2000-2003 transmission, also the guy on the phone says possible 6 speed...? Went and got the part put it in and still no accurate speedo reading.. totally lost now, any help would be appreciated!
 
The 1996-1998 model years use a VSS transmission sensor. The 1999+ uses an OSS sensor. The electrical output of the two sensors are NOT compatible with each other. The sensor type used has to match the PCM and the wiring harness.

The VSS sensor is driven via a worm gear. The OSS sensor uses a reluctor wheel (like ABS tone rings). To further complicate things, in 2004, Ford changed the number of teeth used on the OSS reluctor wheels. Ford's intent was to standardize across the product line.

So you see that the model year of the donor car is important.

Your 1997 came with a VSS sensor. A transmission from a later MY will have a OSS sensor. For more information about the differences between VSS and OSS, check out:

T-45 Tail Shaft Swap - Ford Mustang Forums

An extended range SpeedCal can convert an OSS sensor signal to what a VSS style car is expecting.