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Test TC-10A - O2S Stays Below Center (Lean) (DTC 51)

WARNING: This page is about a different car, the 1995 Dodge Ram Wagon, 1995 Dodge Ram Van, 1995 Dodge Pickup, and 1995 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
  1. Start engine and apply parking brake. Allow engine to reach normal operating temperature. Using scan tool, set engine speed to 1500 RPM. Using scan tool, read Oxygen Sensor (O2S) voltage. If O2S voltage is more than .5 volt, condition required to set DTC is not present at this time. Go to next step. If O2S voltage is zero volts, go to step 5). If O2S voltage is less than .5 but more than zero volts, go to step 3).
  2. O2S STAYS BELOW CENTER (LEAN) DTC sets if O2S signal stays less than .5 volt without changing for more than 8 minutes. Possible causes are major vacuum leak, low fuel pressure, other engine sensor calibrations, failed ignition system, failed sensor, and fuel contamination. Go to TEST NTC-1A.
  3. Check for tracking from O2S connector, O2S signal circuit (Black/Dark Green wire) to sensor ground circuit (Black/Light Blue wire). Go to next step.
  4. Check O2S connectors for excessive dirt and grease build-up. If there is excessive dirt and grease build-up, clean and repair connector(s) as necessary. Perform TEST VER-2. If no excessive dirt or grease build-up is present, a condition causing engine to run lean is indicated. Go to TEST NTC-1A.
  5. Using scan tool, stop actuation tests. Turn ignition switch to ON position, leaving engine off. Disconnect and inspect O2S connector. Repair as necessary. Using scan tool, read O2S voltage. If O2S voltage is .5 volt, replace O2S. Perform TEST VER-2. If O2S voltage is not .5 volt, turn ignition off.
  6. Disconnect and inspect Powertrain Control Module (PCM) connector for damaged, pushed-out or miswired terminals. Repair as necessary. Perform TEST VER-2.
  7. If connector is okay, put scan tool in ohmmeter mode. Using scan tool, check resistance of O2S connector, O2S signal circuit (Black/Dark Green wire). If resistance is less than 5 ohms, repair short to ground in Black/Dark Green wire. Perform TEST VER-2. If resistance is more than 5 ohms, replace PCM. Perform TEST VER-2.
  8. Start engine. Allow engine to run until normal operating temperature is reached. Using scan tool, set engine speed to 1500 RPM and read O2S voltage. If voltage is not always less than .5 volt, condition required to set DTC is not present at this time. Stop all tests and go to next step. If voltage is always less than .5 volt, go to step 10).
  9. 02S STAYS BELOW CENTER (LEAN) DTC sets if O2S output voltage stays at less than .5 volt without changing for more than 8 minutes. Possible causes are: large vacuum leak, low fuel pressure, other engine sensor calibration failures, ignition system failure, O2S failure or fuel contamination. Go to TEST NTC-1A.
  10. Using scan tool, check if O2S voltage is always zero volts. If O2S voltage is always zero volts, go to next step. If O2S voltage is not always zero volts, a condition causing engine to run lean is present. Go to TEST NTC-1A.
  11. Using scan tool, stop all actuation tests. Turn ignition on with engine off. Disconnect O2S connector. Using scan tool, read O2S state. If O2S state is at center, replace O2S. Perform TEST VER-2.
  12. If O2S state is not at center, turn ignition off. Disconnect Powertrain Control Module (PCM) connector. Using scan tool in ohmmeter mode, check resistance of O2S connector (harness side), signal circuit (Dark Green/White wire).
  13. If resistance is less than 5 ohms, repair short to ground in Dark Green/White wire. Perform TEST VER-2. If resistance is more than 5 ohms, replace PCM. Perform TEST VER-2.
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