Speedometer woes on a 94 TD

[600K]

the speedo quit in my jetta.   The chiltons bible says there should be 12v and ground in the three place plug and the center is for the hall signal.  No problem with the 12 v and ground, but I have 6v pos at the center wire when unpluged or pluged in.There is nothing about voltage at the center wire.  Nothing changes when I spin the wheel, it should cycle  hi to low volts.  I'm chasing the wiring charts, but wondering if anyone has any ideas? 

[Vincent Waldon]

Backing up just a bit... an important distinction is:  does the odo still work?  If not, further troubleshooting of the speed sensor is definitely the right way to go... you should see a signal on the middle line that alternates between ground and + as you rotate the tire.

If the ODO does work the the sensor and wiring is fine and your cluster has simply experienced one of the many common failure modes A3 clusters have... pretty much not repairable without specialized knowledge and equipment.

[600K]

 It does light up, but doesn't change. 

[Vincent Waldon]

OK, then if you're seeing that the sensor is getting +12 and ground but is not sending out a varying signal as the tire is rotated the immediate suspect is the sensor... you could try pulling and turning it by hand (while still plugged in) to ensure it's not a transfer issue internal to the transaxle.