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Home >> Geo >> 1995 >> Prizm LSi, 1.8 8, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 1.8L >> DTC Charts >> DTC 42, Vehicle Speed Sensor, Open Or Shorted Circuit >> Notes
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DTC 42, Vehicle Speed Sensor, Open Or Shorted Circuit: Notes

Vehicle Speed Sensor (VSS) is an electronic relay mounted on transaxle. As transaxle rotates VSS, the VSS provides speedometer with a vehicle speed input (voltage pulses). This signal drives speedometer. Speedometer converts vehicle speed input into a more precise waveform and provides PCM, and cruise control module with a vehicle speed input. PCM converts this input (ground pulses) into vehicle speed. DTC 42 will set if vehicle speed input is not sensed at PCM with engine speed 3000-5000 RPM and transaxle in gear, for at least 8 seconds.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Determines if VSS is functioning properly.
  2. Checks for an open in power feed to VSS.
  3. Checks for an open or short in PCM speed input circuit or for a faulty PCM.
  4. Determines if PCM or speedometer is faulty.
  5. Checks for an open in ground to VSS.
  6. Checks for an open in power feed to speedometer.
  7. Determines if VSS or speedometer is faulty.