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Home >> GMC >> 1987 >> Forward Control 6.2 J, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 13 (Engine Controls - Theory & Operation - Gasoline) >> Computerized Engine Controls >> Input Devices >> Vehicle Speed Sensor (VSS)

Vehicle Speed Sensor (VSS)

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Yukon, 1994 GMC Suburban, 1994 GMC Pickup, 1994 GMC Cab & Chassis, and 1994 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.

VSS is a Permanent Magnet (PM) generator mounted in transmission or transfer case. The VSS sends a pulsing signal to either the PCM or Digital Ratio Adapter Controller (DRAC), which passes the signal on to the PCM. PCM then converts this signal into Miles Per Hour (MPH) by monitoring the time interval between pulses. PCM uses this sensor input in controlling converter clutch engagement, shift speed, etc.

On all models, a VSS buffer is built into the DRAC.

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