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Home >> Pontiac >> 2000 >> Firebird Base, 2D Convertible, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P1571: Traction Control System (TCS) Torque Request Circuit (Except CAMARO & Firebird) >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . After performing OBD system check, go to next step.
  2. Turn ignition on. Using scan tool, read DESIRED TORQUE. If PWM is about 100 percent, go to step  4. If PWM is not as specified, go to next step.
  3. Turn ignition off. Disconnect Electronic Brake and Traction Control Module (EBTCM) connector. Turn ignition on. Using a DVOM, check voltage between engine ground and EBTCM harness connector desired torque PWM circuit. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step  6.
  4. Turn ignition off. Connect ABS/TCS Pinout Box and Adapter (J-39700-25) between EBTCM and EBTCM connector. Using DVOM in Hertz (Hz) scale, check frequency between engine ground and desired torque PWM circuit. Turn ignition on. If frequency is 120-135 Hz, go to next step. If frequency is not as specified, go to step  7.
  5. Using DVOM in duty cycle scale, check duty cycle between engine ground and desired torque PWM circuit. Turn ignition on, engine off. If duty cycle is 5-95 percent, go to step  9. If measured duty cycle is not as specified, go to step  7.
  6. Turn ignition off. Disconnect harness PCM. Turn ignition on. Check desired torque PWM circuit for open, short to ground or short to voltage. Repair as necessary. After repairs are complete, go to step  11. If circuit is okay, go to step  9.
  7. Check for faulty connection at EBTCM. Repair as necessary. After repairs, go to step  11. If connection is okay, go to next step.
  8. Replace EBTCM. After replacing EBTCM, go to step  11.
  9. Check for faulty connection at PCM. Repair as necessary. After repairs, go to step  11. If connection is okay, go to next step.
  10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  11. Clear DTCs. Turn ignition on and observe DESIRED TORQUE PWM scan tool display. If scan tool indicates that this about 100, repair is complete. If scan tool does not indicate that this about 100 percent, return to step  2.


  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . After performing OBD system check, go to next step.
  2. Turn ignition off. Disconnect EBTCM harness connector. Turn ignition on. Using a DVOM, check voltage between ground and DT circuit at EBTCM connector. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step  4.
  3. Turn ignition on, with engine off. Using scan tool, read DTCs. If any ABS system DTCs are set, diagnose affected ABS DTCs first. If no ABS system DTCs are set, see DIAGNOSTIC AIDS .
  4. Using a DVOM, check voltage between ground and DT circuit at EBTCM connector. If battery voltage is present, go to step  7. If battery voltage is not present, go to next step.
  5. Using a test light connected to battery voltage, probe DT circuit at EBTCM connector. If test light illuminates, go to step  8. If test light does not illuminate, go to next step.
  6. Check for open in DT circuit. Repair as necessary. After repairs, go to step  11. If circuit is okay, go to step  9.
  7. Repair short to battery voltage on DT circuit. After repairs, go to step  11.
  8. Repair short to ground on DT circuit. After repairs, go to step  11.
  9. Check terminal connections at PCM. Repair terminals as necessary. After repairs, go to step  11. If terminals are okay, go to next step.
  10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  11. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step  2.
  12. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.
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