Got the Optishift installed
Elder User
Joined: Apr 2002
Posts: 950
Likes: 2
From: West Bend
Wiring diagrams coming to help with kicking out the old PCM 
http://www.airplanesathome.com/FTEpics/E4ODTach.gif
http://www.airplanesathome.com/FTEpics/E4ODSpeedo.gif
OPERATION
The VSS is a variable reluctance sensor mounted in the rear axle housing. It monitors rear axle speed by sensing teeth on an exciter ring mounted on the ring gear. As teeth pass the sensor pole piece, an AC voltage with a frequency proportional to average rear wheel speed is induced. This signal is sent to the Programmable Speedometer/Odometer Module (PSOM) . The PSOM processes this input signal information and relays it to the powertrain control module and the speed control module. This signal tells the powertrain control module the vehicle speed in miles per hour. The PCM uses this signal as an input in determining shift scheduling and Electronic Pressure control.
According to the description, it looks like the VSS should go straight to the speedo and the speedo feeds the PCM so it would seem the speedo should still work?
Tachometer you should be able to just rewire direct to the tachometer it appears.
http://www.airplanesathome.com/FTEpics/E4ODTach.gif
http://www.airplanesathome.com/FTEpics/E4ODSpeedo.gif
OPERATION
The VSS is a variable reluctance sensor mounted in the rear axle housing. It monitors rear axle speed by sensing teeth on an exciter ring mounted on the ring gear. As teeth pass the sensor pole piece, an AC voltage with a frequency proportional to average rear wheel speed is induced. This signal is sent to the Programmable Speedometer/Odometer Module (PSOM) . The PSOM processes this input signal information and relays it to the powertrain control module and the speed control module. This signal tells the powertrain control module the vehicle speed in miles per hour. The PCM uses this signal as an input in determining shift scheduling and Electronic Pressure control.
According to the description, it looks like the VSS should go straight to the speedo and the speedo feeds the PCM so it would seem the speedo should still work?
Tachometer you should be able to just rewire direct to the tachometer it appears.
Elder User
Joined: Apr 2002
Posts: 950
Likes: 2
From: West Bend
Addition: Looks like both the ground and the signal lines for the tach sensor go into the PCM. So you'll need to rewire both wires, not just move the one. Trans diagrams looks to back up the description in that the output from the speedometer (GY/BK) is used to feed as a speed signal into the PCM.
Best of luck!
Best of luck!
Elder User
Joined: Aug 2007
Posts: 728
Likes: 0
depends on year model
92 and up have the PSOM module and us the vss sensor in the rear axle
91 and earlier use a mechanical cable for speedo and vss sensor in trans for tcm
the TCM recieves the tach signal and modifies the signal and send it to the tach
you cannot wire the sensor directly to the tach
and when the vss has one wire that is also grounded ,
the purpose of grounding one leg is to change the sensors output signal to a half sine wave
92 and up have the PSOM module and us the vss sensor in the rear axle
91 and earlier use a mechanical cable for speedo and vss sensor in trans for tcm
the TCM recieves the tach signal and modifies the signal and send it to the tach
you cannot wire the sensor directly to the tach
and when the vss has one wire that is also grounded ,
the purpose of grounding one leg is to change the sensors output signal to a half sine wave
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