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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 52 (Automatic Transaxle Diagnosis - 4T65-E) >> Diagnostic Tests >> DTC P0712: Transmission Fluid Temperature Sensor Circuit (Low Input) >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Buick Regal, 2002 Buick Century, 2001 Buick Regal, and 2001 Buick Century. 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 failure records. Using the CLEAR INFO function erases the failure records from the PCM. Record the failure records. Clear the DTCs. With a scan tool, observe the TFT sensor parameter. Does the scan tool indicate that the TFT sensor voltage is less than 0.2 volt? If so, go to next step. If not, see DIAGNOSTIC AIDS  .
  3. Turn ignition off. Disconnect the transaxle in-line 20-way connector (additional DTCs will set). Turn ignition on, engine off. Observe the TFT sensor voltage. Does the scan tool indicate that the TFT sensor voltage is greater than 4.9 volts? If so, go to step  5 . If not, go to next step.
  4. Test the signal circuit (CKT 1227) of the TFT sensor for a short to ground between the PCM connector and the transaxle in-line 20-way connector. Did you find and correct the condition? If so, go to step  11 . If not, go to step  10 .
  5. Connect the Jumper Harness (J 44152) to the transaxle side of the 20-way connector. Using the Connector Test Adapter Kit (J 35616-A), connect DVOM from terminals "L" to "M" of the jumper harness. Measure the resistance. Does the resistance measure within 3164-3867 ohms at 68°F (20°C) to 225-285 ohms at 190°F (88°C)? If so, go to next step. If not, go to step  7 .
  6. Test the signal circuit (CKT 1227) of the TFT sensor for a short to ground between the transaxle in-line 20-way connector and the TFT sensor. Is the resistance greater than 10 k/ohms? IF so, see DIAGNOSTIC AIDS  . If not, go to step  9 .
  7. Disconnect the TFT sensor from the transaxle internal wiring harness. Using the DVOM, measure the resistance between terminals "L" and "M" of the jumper harness. Is the resistance greater than 10 k/ohms? If so, go to next step. If not, go to step  9 .
  8. Replace the TFT sensor. See TRANSMISSION FLUID TEMPERATURE SENSOR  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  11 .
  9. Replace the transaxle internal wiring harness. See TRANSAXLE INTERNAL WIRING HARNESS  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 to verify the repair:
    • Select DTC.
    • Select CLEAR INFO.
    • Turn ignition on, engine off.
    • The transmission fluid temperature signal voltage must be greater than 0.2 volt for 10 seconds.
    • Select SPECIFIC DTC.
    • Enter DTC P0712.

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

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