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Test NTC-12: Checking O2S Heater

NOTE: Possible causes are: downstream O2S defective, upstream O2S defective, ASD relay output circuit open or O2S heater ground circuit open.
  1. Turn ignition on with engine off. Using scan tool, actuate O2S heater test. Wait 2 minutes for O2S voltage to stabilize. Using scan tool, read upstream O2S voltage. If O2S voltage stays between .4-.6 volts, this indicates a problem with that circuit. If upstream O2S voltage is between .4-.6 volts, go to next step. If voltage is not between .4-.6 volts, go to step  5 .
  2. Turn ignition off. Disconnect upstream O2S connector. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of O2S heater ground circuit between upstream O2S (Black wire) and chassis ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair appropriate open O2S heater ground circuit. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
  3. Using scan tool, actuate O2S heater test. Using a DVOM, check voltage of O2S connector (harness side) ASD relay output circuit (Dark Green/Orange wire). If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open ASD relay output circuit. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
  4. If no other potential causes are remaining, upstream O2S is assumed to be defective. Replace upstream O2S. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
  5. Using scan tool, actuate O2S heater test. Wait 2 minutes for O2S voltage to stabilize. Using scan tool, read downstream O2S voltage. If O2S voltage stays between .4-.6 volts, this indicates a problem with that circuit. If downstream O2S voltage is between .4-.6 volts, go to next step. If voltage is not between .4-.6 volts, test is complete.
  6. Using scan tool, actuate O2S heater test. Using a DVOM, check voltage of O2S connector (harness side) ASD relay output circuit (Dark Green/Orange wire). If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open ASD relay output circuit. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
  7. Turn ignition off. Disconnect downstream O2S connector. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of O2S heater ground circuit between downstream O2S (Black wire) and chassis ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair appropriate open O2S heater ground circuit. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
  8. If no other potential causes are remaining, PCM is assumed to be defective. Replace PCM. PCM is located to left of Power Distribution Center (PDC) in engine compartment. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
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