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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 P0740: TCC Enable Solenoid Circuit - Electrical Malfunction >> 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. 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. If DTCs P0753, P0758, P0785 and P1860 are not present, go to next step. If DTCs P0753, P0758, P0785 or P1860 are also present, go to next step. If none of the listed DTCs are set, go to step  4.
  3. Check TCC circuit fuse. See WIRING DIAGRAMS . If fuse is open, go to step  9. If fuse is okay, go to next step.
  4. Turn ignition off. Disconnect transmission 20-pin in-line harness connector. Connect appropriate jumper harness to engine side of in-line harness connector. Turn ignition on, engine off. Using test light connected to ground, probe terminal "E" at jumper harness. If test light illuminates, go to next step. If test light does not illuminate, go to step  12.
  5. Connect test light between terminals "E" and "T" at jumper harness. Using scan tool, command TCC solenoid valve on and off 3 times. If test light turns on and off as solenoid is commanded, go to step  7. If test light does not turn on and off as solenoid is commanded, go to next step.
  6. If test light is always on, go to step  13. If test light is not always on, go to step  14.
  7. Connect appropriate jumper harness to transmission side of transmission 20-pin in-line harness connector. Measure resistance between terminals "E" and "T" at jumper harness. If resistance is 21-33 ohms, go to next step. If resistance is not 21-33 ohms, go to step  15.
  8. Measure resistance between ground and terminal "E", and then between ground and terminal "T" at jumper harness. If resistance is greater than 250 ohms, see DIAGNOSTIC AIDS . If resistance is not greater than 250 ohms, go to step  15.
    9. NOTE: Condition affecting TCC solenoid valve circuit may be caused by a fault in other circuits spliced to TCC solenoid valve circuit.
  9. Check TCC solenoid valve ignition feed circuit for short to ground between in-line harness connector and engine wiring harness junction block. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to next step.
    10. NOTE: Condition affecting TCC solenoid valve circuit may be caused by a fault in other circuits spliced to TCC solenoid valve circuit.
  10. Check TCC solenoid valve ignition feed circuit for short to ground between in-line harness connector and TCC solenoid valve. If circuit is shorted, go to step  15. If circuit is okay, go to next step.
  11. Check each solenoid for short to ground. Replace faulty solenoid as necessary. See appropriate AUTOMATIC article in TRANSMISSION SERVICING. After repairs, go to next step.
    12. NOTE: Condition affecting TCC solenoid valve circuit may be caused by a fault in other circuits spliced to TCC solenoid valve circuit.
  12. Check for open in TCC solenoid valve ignition feed circuit. Repair as necessary. After repairs, go to step  17.
  13. Check TCC solenoid valve control circuit for short to ground between in-line harness connector and PCM. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to step  16.
  14. Check TCC solenoid valve control circuit for open or short to voltage between in-line harness connector and PCM. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to step  16.
  15. Replace transmission wiring harness assembly (including TCC solenoid valve). See appropriate AUTOMATIC article in TRANSMISSION SERVICING. After repairs, go to step  17.
  16. Replace PCM. After replacement, program PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs, go to next step.
  17. Using scan tool, clear DTCs. Test drive vehicle with TCC on and off while monitoring TCC solenoid valve parameter. Ensure voltage decreases to zero when TCC solenoid is commanded on, and voltage increases to battery voltage when commanded off. Conditions must be met for 5 seconds. Check for DTCs. If DTC P0740 does not return, system is okay. If DTC P0740 returns, repeat step  1.
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