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Home >> Cadillac >> 1998 >> Seville STS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1644 - Delivered Torque Output Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
  2. Turn ignition on. Using scan tool in ENGINE 3 mode, observe DELIVERED TORQUE DRIVER display. If scan tool display indicates OK, fault is not present. See DIAGNOSTIC AIDS. If scan tool display does not indicate OK, go to next step.
  3. If scan tool display indicates OPEN, go to next step. If scan tool display does not indicate OPEN, go to step 6).
  4. Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C2. Turn ignition on. Using DVOM, check voltage between ground and delivered torque PWM output circuit at PCM harness connector C2. If voltage reading is 10 volts or greater, go to step 13). If voltage reading is not 10 volts or greater, go to next step.
  5. Turn ignition to LOCK position. Disconnect EBTCM harness connector. Check resistance of delivered torque PWM output circuit between PCM harness connector and EBTCM harness connector terminals. If resistance is 5 ohms or less, go to step 12). If resistance is not 5 ohms or less, go to step 9).
  6. Turn ignition to LOCK position. Disconnect EBTCM harness connector. Turn ignition on. If scan tool display indicates OPEN, go to step 12). If scan tool display does not indicate OPEN, go to next step.
  7. Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C2. Turn ignition on. Using DVOM, check resistance between ground and delivered torque PWM output circuit at PCM harness connector C2 terminal. If voltage is greater than .5 volt, go to step 10). If voltage is not greater than .5 volt, go to next step.
  8. Using DVOM, check resistance between ground and delivered torque PWM output circuit at PCM harness connector C2 terminal. If resistance is 10,000 ohms or greater, go to step 13). If resistance is not 10,000 ohms or greater, go to step 11).
  9. Repair open in delivered torque PWM output circuit.
  10. Repair short to voltage in delivered torque PWM output circuit.
  11. Repair short to ground in delivered torque PWM output circuit.
  12. Fault is in the EBTCM system. Diagnose EBTCM. See ANTI-LOCK BRAKE SYSTEM article in BRAKES section. If fault is not found in EBTCM system, check for faulty terminal contact to EBTCM. If terminal contact is okay, replace EBTCM.
  13. Check terminal contact at PCM harness connector C2. Repair as necessary. If terminal contact is okay, go to next step.
  14. Replace PCM. Program replacement PCM using required equipment.
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