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Home >> GMC >> 2002 >> C3500 HD 8.1 G, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 69 (Automatic Transmission Diagnosis - 4L80-E (Gasoline)) >> Diagnostic Tests >> DTC P0717: Input Speed Sensor Circuit - Low Input >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 GMC Cab & Chassis Sierra and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  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 DTCs, use the scan tool to record the freeze frame and failure records. Using the CLEAR INFO function erases the freeze frame and failure records from the PCM. Record the freeze frame and failure records. Clear the DTCs. With the vehicle in Park, start the engine and idle greater than 500 RPM. Select scan tool ISS and engine RPM. Is the ISS greater than 50 RPM? If so, see DIAGNOSTIC AIDS  . If not, go to next step.
  3. Turn ignition off. Disconnect the PCM connector C2. Additional DTCs may set. Using DVOM set to AC scale, probe across PCM connector C2 terminals No. 22 and 23. Remove the fuel pump relay. With the vehicle in Park, crank the engine. Does the voltage measure above 0.5 volt AC? If so, go to step  10 . If not, go to next step.
  4. Turn ignition off. Remove the connector from the ISS. Measure the resistance between ISS terminals "A" and "B". Does the sensor resistance measure 1042-2088 ohms? If so, go to next step. If not, go to step  9 .
  5. Select AC scale on the DVOM. With the vehicle in Park, crank the engine. Does the voltage measure greater than 0.5 volt AC? If so, go to step  7 . If not, go to next step.
  6. Remove the ISS from the transmission. Inspect the ISS. Inspect the forward clutch housing rotor teeth for damage. Did you find and correct the condition? If so, go to step  11 . If not, go to step  9 .
  7. Test the ISS high signal circuit (1230) for an open or short to ground. Did you find and correct the condition? If so, go to step  11 . If not, go to next step.
  8. Test the ISS low signal circuit (1231) for an open or short to ground. Did you find and correct the condition? If so, go to step  11 . If not, see DIAGNOSTIC AIDS  .
  9. Replace the ISS. See SPEED SENSORS  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  11 .
  10. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  11. Perform the following procedure in order to verify the repair:
    • Select DTC.
    • Select CLEAR INFO.
    • The vehicle in drive range and the engine must be running.
    • Vehicle speed greater than 12 MPH.
    • The PCM must see an input speed greater than 450 RPM for greater than 2 seconds.
    • Select SPECIFIC DTC.
    • Enter DTC P0717.

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

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