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Home >> Dodge and Ram >> 1996 >> Caravan Base, 3.3 R >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 5 (Engine Controls - Tests W/Codes - 2.4L) >> Trouble Code Tests >> Test TC-105A - Downstream O2 Sensor Heater Failure
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Test TC-105A - Downstream O2 Sensor Heater Failure

WARNING: This page is about a different variant/trim than selected.
NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION DIRECTORY  . For wiring diagram, see WIRING DIAGRAMS - 2.4L article.
  1. Using scan tool, check for stored Diagnostic Trouble Codes (DTCs). If DTCs exist that are related to the downstream oxygen sensor, refer to appropriate test for the specified DTC. If no DTCs exist that are related to the downstream oxygen sensor, go to next step.
  2. Turn ignition on with engine off. Wait 3 minutes and then use scan tool to monitor downstream oxygen sensor voltage for a few minutes. Once downstream oxygen sensor voltage stabilizes between .4 and .6 volt, using scan tool, actuate downstream oxygen sensor heater test while monitoring downstream oxygen sensor voltage for at least 2 minutes.
  3. If downstream oxygen sensor voltage still remains .4-.6 volt, go to step 5). If downstream oxygen sensor voltage does not remain .4-.6 volt, go to next step.
  4. Conditions required to set DTC are not present at this time. DTC may be stored in Powertrain Control Module (PCM) if no downstream oxygen sensor voltage signal is received when PCM powers up the downstream oxygen sensor heater. Possible causes are: open heater element circuit, downstream oxygen sensor failure, defective PCM, defective connector terminals or wiring. Stop downstream oxygen sensor heater test. Test is complete.
  5. Disconnect connector at downstream oxygen sensor, mounted on exhaust pipe, behind catalytic converter. Using scan tool in voltmeter mode, check voltage at terminal No. 2 (Dark Green/Orange wire) on wiring harness side of connector for downstream oxygen sensor while still performing downstream oxygen sensor heater test.
  6. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open circuit in Dark Green/Orange wire from Auto Shutdown (ASD) relay. The ASD relay is located in power distribution center at driver's side front corner of engine compartment, near battery.
  7. Stop downstream oxygen sensor heater test. Using external ohmmeter, check resistance of downstream oxygen sensor heater between terminals No. 1 and 2 on oxygen sensor side of connector for downstream oxygen sensor. See Figure for terminal identification.
  8. If resistance 4-20 ohms, go to next step. If resistance is not 4-20 ohms, replace downstream oxygen sensor. Perform TEST VER-5A.
  9. Using scan tool in ohmmeter mode, check resistance at terminal 1 (Black) on wiring harness side of connector for downstream oxygen sensor. If resistance is less than 5 ohms, replace downstream oxygen sensor. Perform TEST VER-5A. If resistance 5 ohms or more, repair open circuit in Black wire and ground. Perform TEST VER-5A.
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