For a complete wiring diagram Refer to Section 8W.When Monitored:Battery voltage above 10.6 volts, ASD is powered up, and O2 heater is off.Set Condition:Desired state does not equal Actual state. One Trip Fault. Three good trips to turn off the MIL.Possible Causes(K199) O2 2/1 HEATER CONTROL CIRCUIT OPEN(Z906) O2 2/1 HEATER GROUND CIRCUIT OPEN(K199) O2 2/1 HEATER CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGEO2 SENSOR PCMAlways perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).1. ACTIVE DTCIgnition on, engine not running.With a scan tool, select View DTCs.Is the DTC Active at this time?YesGo To 2NoRefer to the INTERMITTENT CONDITION Diagnostic Procedure.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 2. O2 HEATER ELEMENTTurn the ignition off.Allow the O2 Sensor to cool down to room temperature.Disconnect the 2/1 O2 Sensor harness connector.Measure the resistance across the O2 Sensor Heater element, between the O2 Heater Control terminal and the Heater ground terminal at the component connector.O2 Heater Element resistance values should be measured at 21.1° C (70° F). The resistance value will vary with different temperature values.Is the O2 Sensor Heater Element resistance between 2.0 and 30.0 ohms?YesGo To 3NoReplace the O2 Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 3. (K199) O2 2/1 HEATER CONTROL CIRCUIT

Ignition on, engine not running.Using a 12-volt test light connected to ground, probe the (K199) O2 2/1 Heater Control circuit in the O2 Sensor harness connector.Make sure the test light is probing the circuit before actuating the Heater Test or a DTC may set and not allow the actuation.With the scan tool, actuate the O2 Heater Test with the Sensor harness connector still disconnected.Does the test light illuminate brightly and flash on and off during the actuation?YesGo To 4NoGo To 54. (Z906) O2 2/1 HEATER GROUND CIRCUIT OPEN

Turn the ignition off.Measure the resistance between an engine ground and the (Z906) O2 2/1 Heater ground circuit in the O2 Sensor harness connector.Is the resistance below 5.0 ohms?YesReplace the O2 Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoRepair the open in the (Z906) O2 2/1 Heater ground circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 5. (K199) O2 2/1 HEATER CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE

Turn the ignition off.Disconnect the C2 PCM harness connector.Ignition on, engine not running.Using a 12-volt test light connected to ground, probe the (K199) O2 2/1 Heater Control circuit in the O2 Sensor harness connector.Does the test light illuminate?YesRepair the short to battery voltage in the (K199) O2 2/1 Heater Control circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoGo To 66. (K199) O2 2/1 HEATER CONTROL CIRCUIT OPEN

Turn the ignition off.Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.Measure the resistance of the (K199) O2 2/1 Heater Control circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?YesGo To 7NoRepair the open in the (K199) O2 2/1 Heater Control circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 7. PCMBefore continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.Were there any problems found?YesRepair as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) NoReplace and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)