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Home › Chevrolet › 2017 › Spark LS, Automatic CVT Trans › Repair and Diagnosis › Transmission › Automatic Trans › Automatic Transmission - JATCO CVT › Diagnostic Information and Procedures › DTC P0721: Output Speed Sensor Performance › Component Testing › K71 Transmission Control Module

K71 Transmission Control Module

  1. Ignition OFF, disconnect the harness connector at the B14A Output Shaft Speed Sensor.
  2. Connect the red lead of the J-38522  variable signal generator to the sensor signal circuit terminal 2. Connect the black lead of the J-38522  variable signal generator to the low reference circuit terminal 1. Plug the power cord of the J-38522  variable signal generator into the cigar lighter.
    NOTE: Testing for steps 2 - 4 is performed on the B14A Output Shaft Speed Sensor harness connector using the GY probes J-35616-2A  .
  3. Set the J-38522  variable signal generator to 12 volts, the Frequency to 30 and the Duty Cycle to 50%.
  4. Ignition ON. Verify the scan tool Transmission OSS parameter is between the following specified ranges as you rotate the frequency switch through the various selections.
    • If not within the specified range, replace the K71 Transmission Control Module.
    • If within the specified range.
  5. K71 Transmission Control Module OK.
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