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Home >> Pontiac >> 1996 >> Firebird Formula, 2D Convertible, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 1 (Engine Control System - Basic Engine Testing - 3.8L) >> On-Board Diagnostic (OBD) System Check >> A-2/A-4, DLC Diagnosis Or No Scan Tool Data
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A-2/A-4, DLC Diagnosis Or No Scan Tool Data

WARNING: This page is about a different variant/trim than selected.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . After performing OBD system check, go to next step.
  2. Turn ignition on with engine off. Connect a test light between DLC terminal No. 16 (Orange wire) and DLC terminal No. 4 (Black/White or Black wire). If test light illuminates, go to step 4). If test light does not illuminate, go to next step.
  3. Connect test light to ground. Using test light, probe DLC terminal No. 16 (Orange wire). If test light illuminates, go to next step 9). If test light does not illuminate, go to step 10).
  4. Turn ignition on with engine off. Using DVOM, check voltage between ground and DLC terminal No. 2 (Purple wire). DVOM should read zero volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 7).
  5. Turn ignition off. Disconnect PCM harness connector. Turn ignition on with engine off. Connect DVOM between battery voltage and DLC terminal No. 2 (Purple wire). DVOM should read zero volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8).
  6. Check for open in circuit (Purple wire) between DLC and PCM connector. If circuit is open, repair as necessary. After repairs, perform OBD system check. If circuit is okay, go to step 11).
  7. Check for short to voltage in circuit (Purple wire) between DLC and PCM connector. If circuit is shorted, repair as necessary. After repairs, perform OBD system check. If circuit is okay, go to step 11).
  8. Check for short to ground in circuit (Purple wire) between DLC and PCM connector. If circuit is shorted, repair as necessary. After repairs, perform OBD system check.
  9. Locate and repair open in DLC ground circuit (Black wire). After repairs, perform OBD system check.
  10. Locate and repair open or short to ground in DLC terminal No. 16 (Orange wire). After repairs, perform OBD system check.
  11. Replace PCM. Perform PCM relearn procedures and then perform OBD system check.
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