LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Pontiac >> 2000 >> Firebird Base, 2D Convertible, Automatic >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System - Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P1518: Throttle Actuator Control (TAC) Module Serial Data Circuit (CAMARO & Firebird) >> Diagnostic Procedures
April 5, 2026: LEMON Manuals is launched! Read the announcement.

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.
    NOTE: If DTC P1120, P1220, P1221, P1515 or P1516 is set, diagnose affected DTC(s) first.
  2. Turn ignition on. Using scan tool, review and record FAILURE RECORDS data and note parameters. Operate vehicle within FAILURE RECORDS conditions. Monitor SPECIFIC DTC INFO for this DTC until this DTC runs. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicates that this DTC failed this ignition, see DIAGNOSTIC AIDS .
  3. Turn ignition off. Disconnect Throttle Actuator Control (TAC) module harness connector. Check voltage between ground and TAC module ignition feed circuit. If voltage reading is zero volts, go to next step If voltage reading is not zero volts, go to step  10.
  4. Turn ignition on. Check voltage between ground and TAC module ignition feed circuit. If battery voltage is present, go to next step. If battery voltage is not present, go to step  12.
  5. Using a test light connected to battery voltage, probe TAC module ground circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step  13.
  6. Check voltage between ground and both TAC module serial data circuits. If voltage reading is 2-5 volts, go to step  14. If voltage reading is not 2-5 volts, go to next step.
  7. If voltage is greater than 2-5 volts, go to step  11. If voltage is not greater than 2-5 volts, go to next step.
  8. If voltage is less than 2-5 volts, go to next step.
  9. Check for open/short to ground in serial data circuit. Repair as necessary. After repairs, go to step  18. If circuit is okay, go to step  16.
  10. Repair short to voltage in ignition feed circuit. After repairs, go to step  18.
  11. Repair short to voltage on TAC module serial data circuit. After repairs, go to step  18.
  12. Repair open/short to ground in ignition feed circuit. After repairs, go to step  18.
  13. Repair open in TAC module ground circuit. After repairs, go to step  18.
  14. Check for poor serial data connections at TAC module. Repair as necessary. After repairs, go to step  18. If connections are okay, go to next step.
  15. Replace TAC module. After replacing module, go to step  18.
  16. Check for poor connections at PCM. Repair as necessary. After repairs, go to step  18. If connections are okay, go to next step.
  17. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  18. 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 that set 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.
  19. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.
scientia non olet · About LEMON Manuals