tomcorbett1980

I have a 94 Buick Lesabre 3.8. Have had problems with transmission shifting automatically for a couple of months. It does shift manually with no problem or slippage. Have replaced vaccuum modulator, done power flush, and changed tranny filter. No luck. Tried Lucas as well. I am trying to test the Vehicle Speed Sensor (VSS), however I do not know the values for voltage/resistance that should be present at the device when idleing or with key in accessory position. What is the best way to test this device and also how much power should be present in the wires leading to it. There are two wires leading to the connector for the VSS, are these + and ground or is one of these data? Any help on this topic would be much appreciated.
Thank-You.

-Tom

HotZ28

Welcome to AF! If your speedometer is working correctly, the VSS is not your problem. The VSS is nothing but an AC generator that sends a pulse signal to the ECU. You may have an ECU problem. I just went through this with my 94 LeSabre that was shifting erratically, alternator voltage drifting, cruise control would not engage, and the TCC would not lock-up. Replaced the ECU and all problems were resolved.

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