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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 66 (Automatic Transmission Diagnosis - 4L80-E (Gasoline)) >> Diagnostic Tests >> DTC P0716: Input Speed Sensor Circuit - Intermittent >> Diagnostic Procedure

Diagnostic Procedure

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  1. Did you perform the diagnostic system check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Install a scan tool. Turn ignition on, engine off. Before clearing the DTC, use the scan tool to record the freeze frame and failure records for reference. The CLEAR INFO function will erase the data. Record the DTC freeze frame and failure records. Clear the DTC. Raise and support the rear axle assembly. Start the engine. Place the transmission in any drive range. With the drive wheels rotating, does the input shaft speed increase with the drive wheel speed? If so, see DIAGNOSTIC AIDS  . If not, go to next step.
  3. Turn ignition off. Disconnect the PCM harness connector C2. Using a DVOM and the Connector Test Adapter Kit (J 35616-A), measure the resistance between PCM harness connector C2 terminals No. 22 and 23. Does the resistance measure 1377-3355 ohms? If so, go to next step. If not, go to step  6 .
  4. Measure the resistance from PCM harness connector C2 terminal No. 22 to ground. Does the resistance measure greater than 50 k/ohms? If so, go to next step. If not, go to step  8 .
  5. Reconnect the PCM connector C2. Disconnect the engine wiring harness from the ISS assembly. Turn ignition on, engine off. Test the high circuit (1230) of the ISS assembly for a short to power. Test the low circuit (1231) of the ISS assembly for a short to power. Did you find and correct the condition? If so, go to step  13 . If not, go to step  12 .
  6. Disconnect the engine wiring harness from the ISS assembly. Measure the resistance of the ISS assembly. Does the resistance measure 1377-3355 ohms? If so, go to next step. If not, go to step  11 .
  7. Was the resistance measured in step  3 greater than 3355 ohms? If so, go to step  9 . If not, go to step  10 .
  8. Test the high circuit (1230) of the ISS assembly for a short to ground. Test the low circuit (1231) of the ISS assembly for a short to ground. Did you find and correct the condition? If so, go to step  13 .
  9. Test the high circuit (1230) of the ISS assembly for an open. Test the low circuit (1231) of the ISS assembly for an open. Did you find and correct the condition? If so, go to step  13 .
  10. Test the high circuit (1230) and the low circuit (1231) of the ISS assembly for a short together. Did you find and correct the condition? If so, go to step  13 .
  11. Replace the ISS assembly. See SPEED SENSORS  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  13 .
  12. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  13. Perform the following procedure to verify the repair:
    • Select DTC.
    • Select CLEAR INFO.
    • The transmission output speed is greater than 450 RPM.
    • No RPM change greater than 300 RPM.
    • All conditions are met for 2 seconds.
    • Select SPECIFIC DTC.
    • Enter DTC P0716.

    Has the test run and passed? If so, system is okay. If not, go to step  1 .

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