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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 72 (Automatic Transmission Diagnosis - 4L80-E (Diesel)) >> Diagnostic Tests >> DTC P0716: Input Speed Sensor Circuit - Intermittent >> 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 DTC, use the scan tool to record the freeze frame and failure records. Using the CLEAR INFO function erases freeze frame and failure records from the PCM. Record the DTC freeze frame and failure records. Clear the DTC. With the transmission in Park, start the engine. Observe ISS on the scan tool. Run the engine to 2000 RPM and hold the engine speed steady. Does the ISS RPM change by more than 1200 RPM at steady engine speed? If so, go to next step. If not, see DIAGNOSTIC AIDS  .
  3. Turn ignition off. Disconnect the ISS harness connector from the ISS sensor. Measure the resistance of the ISS. Does the ISS resistance measure within 1042-2088 ohms? If so, go to next step. If not, go to step  14 .
  4. Using DVOM set to AC scale, connect to the ISS terminals. With the transmission in Park, start the engine. Run the engine to 2000 RPM and hold the engine speed steady. Is the voltage steady and greater than 10 volts AC? If so, go to next step. If not, go to step  14 .
  5. Turn ignition off. Select DC scale on the DVOM. Turn ignition on, engine off. Measure the voltage at both ISS harness connector terminals No. 1 and 2 to a good ground. Does either voltage reading measure greater than 10.5 volts DC? If so, go to next step. If not, go to step  7 .
  6. Test the ISS high signal circuit (1230) for a short to power. Test the ISS low signal circuit (1231) for a short to power. Did you find and correct the condition? If so, go to step  16 . If not, go to step  15 .
  7. Reconnect the ISS harness connector. Turn ignition off. Disconnect the PCM connector C1. Using DVOM set to AC scale, connect to the PCM connector C1 terminals D1 and D11. Remove the fuel solenoid fuse in the fuse/relay center. Turn the ignition to the RUN position and crank the engine while observing the DVOM. Does the voltage measure greater than 0.4 volts AC and steady? If so, go to step  15 . If not, go to next step.
  8. Measure the resistance between PCM connector C1 terminals D1 and D11. Does the circuit resistance measure within 1042-2088 ohms? If so, go to next step. If not, go to step  11 .
  9. Measure the resistance from PCM connector C1 terminal D1 to a good ground. Measure the resistance from PCM connector C1 terminal D11 to a good ground. Does either resistance measure less than 50 k/ohms? If so, go to next step. If not, see DIAGNOSTIC AIDS  .
  10. Test the ISS high signal circuit (1230) and the ISS low signal circuit (1231) for a short to ground. Did you find and correct the condition? If so, go to step  16 .
  11. Does the resistance reading from step  8 measure less than 1042-2088 ohms? If so, go to next step. If not, go to step  13 .
  12. Test the ISS high signal circuit (1230) and the ISS low signal circuit (1231) for a short together. Did you find and correct the condition? If so, go to step  16 .
  13. Test the ISS high signal circuit (1230) and the ISS low signal circuit (1231) for high resistance or an open. Did you find and correct the condition? If so, go to step  16 .
  14. Replace the ISS sensor. See SPEED SENSORS  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  16 .
  15. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
    16. NOTE: Failure to clear codes first may cause poor engine performance and high idle at start up.
  16. Perform the following procedure to verify the repair:
    • Select DTC.
    • Select CLEAR INFO.
    • Start and run the engine greater than 475 RPM.
    • The PCM must see an ISS change of less than 500 RPM for one second.
    • 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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