LEMON Manuals: Even more car manuals for everyone
Home >> Chrysler >> 1993 >> LeBaron GTC, 2D Convertible, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 3.0L >> Fault Code Tests >> Test FC-8A - O2S Stays At Center (DTC 21)

Test FC-8A - O2S Stays At Center (DTC 21)

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION  . For appropriate wiring diagram, see WIRING DIAGRAMS  at end of article.
  1. Start engine. Allow engine to reach normal operating temperature. Using DRB-II, set engine speed to 1500 RPM. Read O2 sensor state. If O2 sensor is switching from rich to lean, go to next step. If O2 sensor is not switching from rich to lean, go to step 5).
  2. While monitoring DRB-II display, wiggle O2 sensor connector and harness. If at any time O2 sensor locked on center, repair open harness or connector where wiggling caused O2 sensor to stay at center. Perform VERIFICATION PROCEDURE VER-2. If at any time O2 sensor is not locked on center, go to next step.
  3. At this time, condition required to set fault is not present. O2S STAYS AT CENTER fault sets if O2 sensor output voltage stays at 0.5 volt for 1.5 minutes with engine temperature more than 170°F (76.6°C), and engine running for 2 minutes. Possible causes are: O2 sensor circuit open or O2 sensor failure. Go to next step.
  4. Inspect O2 sensor wiring and connectors. Repair wiring and connectors as required. Perform VERIFICATION PROCEDURE VER-2. If wiring and connectors are okay, test is complete. Perform VERIFICATION PROCEDURE VER-2.
  5. If O2 sensor was not switching from rich to lean in step 1), disconnect O2 sensor connector. Place DRB-II in ohmmeter mode. Using DRB-II, check resistance of O2 sensor connector ground circuit (Black/Light Blue wire).
  6. If resistance is more than 5 ohms, repair open in Black/Light Blue wire. Perform VERIFICATION PROCEDURE VER-2. If resistance is less than 5 ohms, go to next step.
  7. Connect a jumper wire between O2 sensor connector signal circuit (Black/Dark Green wire) and positive battery terminal. Using DRB-II, read O2 sensor voltage value. If voltage is more than one volt, replace O2 sensor. Perform VERIFICATION PROCEDURE VER-2. If voltage is less than one volt, go to next step.
  8. Turn ignition off. Disconnect Powertrain Control Module (PCM) connector. Disconnect jumper wire. Using an external ohmmeter, check resistance of O2 sensor signal circuit (Black/Dark Green wire) between O2 sensor connector and PCM connector terminal No. 41.
  9. If resistance is less than 5 ohms, replace PCM. Perform VERIFICATION PROCEDURE VER-2. If resistance is more than 5 ohms, repair open Black/Dark Green wire. Perform VERIFICATION PROCEDURE VER-2.
scientia non olet · About LEMON Manuals