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Vehicle Speed Sensor (VSS)

  1. If speedometer is inoperative, turn ignition on. Using a DVOM or test light, measure voltage at Pink/Black wire of VSS module connector. Battery voltage should be present.
  2. If zero volts are present, check ECM fuse, check for open in Pink/Black wire from ECM fuse. If battery voltage is present, check VSS ground circuit.
  3. Unplug connector at VSS. Using Signal Generator/Instrument Panel Tester (J-33431-B) and Adapter (J-33431-4), backprobe VSS connector terminal "A" (Purple wire) with positive probe and negative lead to ground.
  4. Turn tester on and set to 54 MPH (60 Hz). Speedometer should read approximately 54 MPH. If speedometer does not read 54 MPH, check for short to ground, short to voltage in Purple wire, or poor connection at VSS or module. If wiring or connectors are okay, replace VSS module.
  5. If speedometer reads 54 MPH, remove tester negative lead from ground and backprobe VSS connector terminal "B" (Yellow) wire. Speedometer should read approximately 54 MPH.
  6. If speedometer does not read 54 MPH, check for short to voltage or open in Yellow wire. Ensure all VSS connections are tight. If wire and connectors are okay, replace VSS module. If speedometer reads 54 MPH, check for poor connections at VSS. If connectors are okay, replace VSS.
  7. If trouble Code 24 is set, go to step 1). If Code 24 is not set, disconnect VSS module Black 3-pin connector. Using tester, connect positive lead to VSS module terminal "C" (Brown wire) and negative lead to ground.
  8. Turn tester on and set to 54 MPH (60 Hz). Speedometer should read approximately 54 MPH. If speedometer reads 54 MPH, check for poor connection at VSS module terminal "C" (Brown wire). If connector is okay, replace VSS module.
  9. If speedometer does not read 54 MPH, check Brown wire for short to voltage, short to ground or open. Ensure instrument cluster connector terminal No. 28 (Brown wire) is okay. If wire and connectors are okay, service instrument cluster.
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