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Home >> Geo >> 1991 >> Prizm Base, 4D Hatchback, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> PRIZM GSi CODE CHARTS (VIN 5) >> Code 42, Vehicle Speed Sensor (VSS) Circuit

Code 42, Vehicle Speed Sensor (VSS) Circuit

ECM provides a 12-volt signal to the Vehicle Speed Sensor (VSS). VSS will toggle the signal low and high, indicating vehicle is moving. Code 42 is set if signal line stays high or low for 4 seconds or more.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. If speedometer is inoperative, it could be the cause of Code 42.
  2. The ECM supplies B+ to VSS.
  3. The VSS, located on back of instrument panel, will toggle B+ supplied by ECM.
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