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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission Diagnosis - 4L60-E >> Diagnostic Tests >> DTC P0712: TFT Sensor Circuit - Low Input >> Diagnostic Procedure

Diagnostic Procedure

  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. Check transmission fluid level. Fill if necessary. See appropriate AUTOMATIC article in TRANSMISSION SERVICING. Go to next step.
  3. Connect scan tool to DLC. Turn ignition on, engine off. Using scan tool, record freeze frame and failure records for reference, and then clear DTCs. Using scan tool, read TFT sensor signal voltage. If TFT sensor signal voltage is greater than .2 volt, see DIAGNOSTIC AIDS . If TFT sensor signal voltage is not greater than .2 volt, go to next step.
  4. Turn ignition off. Disconnect transmission 20-pin in-line harness connector. Turn ignition on, engine off. If TFT sensor signal voltage is greater than 4.92 volts, go to next step. If TFT sensor signal voltage is not greater than 4.92 volts, go to step  7.
  5. Install appropriate jumper harness on transmission side of 20-pin in-line harness connector. Measure resistance of TFT sensor circuits between terminals "L" and "M". If resistance is 3088-3942 ohms at 68°F (20°C), or 159-198 ohms at 212°F (100°C), see DIAGNOSTIC AIDS . If resistance is not as specified, go to next step.
  6. Check TFT sensor signal circuit for short to ground between transmission 20-pin in-line harness connector and TFT sensor. If circuit is shorted, go to step  9. If circuit is okay, go to step  8.
  7. Check TFT sensor signal circuit for short to ground between transmission 20-pin in-line harness connector and PCM. Repair as necessary. After repairs, go to step  11. If circuit is okay, go to step  10.
    8. NOTE: TFT sensor is part of TFP manual valve position switch.
  8. Replace TFT sensor. See appropriate AUTOMATIC article in TRANSMISSION SERVICING. After repairs, go to step  11.
  9. Replace transmission wire harness assembly. See appropriate AUTOMATIC article in TRANSMISSION SERVICING. After repairs, go to step  11.
  10. Replace PCM. After replacement, program PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs, go to next step.
  11. Using scan tool, clear DTCs. Turn ignition on, engine off. Ensure TFT sensor indicates a voltage greater than .2 volt for 10 seconds. Check for DTCs. If DTC P0712 does not return, system is okay. If DTC P0712 returns, go to step  1.
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