For a complete wiring diagram Refer to Section 8WWhen Monitored:With the ignition on and the O2 1/1 Sensor at operating temperature.Set Condition:The ECM detects a short to ground on the (K902) O2 1/1 Negative Current Control circuit for 2.0 seconds.Possible CausesINTERMITTENT DTC(K902) O2 1/1 NEGATIVE CURRENT CONTROL CIRCUIT SHORTED TO GROUND(K902) O2 1/1 NEGATIVE CURRENT CONTROL CIRCUIT SHORTED TO THE (K79) O2 1/1 HEATER CONTROL CIRCUIT(K902) O2 1/1 NEGATIVE CURRENT CONTROL CIRCUIT OPEN OR HIGH RESISTANCEOXYGEN SENSORENGINE CONTROL MODULE (ECM)Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)1. DTC IS ACTIVEIgnition on, engine not running.With the scan tool, Clear DTCs in the Engine Control Module (ECM).Start the engine.Allow the engine to reach normal operating temperature.Monitor the scan tool for at least two minutes.With the scan tool, select View DTCs.Is the status Active for this DTC?YesGo To 2 NoRefer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)2. (K902) O2 1/1 NEGATIVE CURRENT CONTROL CIRCUIT SHORTED TO GROUND

Turn the ignition off.Disconnect the Oxygen Sensor harness connector.Disconnect the Engine Control Module (ECM) harness connector.Measure the resistance between ground and the (K902) O2 1/1 Negative Current Control circuit in the Oxygen Sensor harness connector.Is the resistance above 1000 ohms?YesGo to 3NoRepair the (K902) O2 1/1 Negative Current Control circuit for a short to ground. Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)3. (K902) O2 1/1 NEGATIVE CURRENT CONTROL CIRCUIT SHORTED TO THE (K79) O2 1/1 HEATER CONTROL CIRCUIT

Measure the resistance between the (K902) O2 1/1 Negative Current Control circuit and the (K79) O2 1/1 Heater Control circuit in the Oxygen Sensor harness connector.Is the resistance above 1000 ohms?YesGo to 4NoRepair the (K902) O2 1/1 Negative Current Control circuit for a short to the (K79) O2 1/1 Heater Control circuit.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)4. (K902) O2 1/1 NEGATIVE CURRENT CONTROL CIRCUIT OPEN OR HIGH RESISTANCE

Measure the resistance of the (K902) O2 1/1 Negative Current Control circuit between the Oxygen Sensor harness connector and the Engine Control Module (ECM) harness connector.Is the resistance below 10.0 ohms?YesGo to 5NoRepair the (K902) O2 1/1 Negative Current Control circuit for an open circuit or high resistance.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)5. OXYGEN SENSORConnect the Engine Control Module (ECM) harness connector.Replace the Oxygen Sensor in accordance with the Service Information.Start the engine.Allow the engine to reach normal operating temperature.Monitor the scan tool for at least two minutes.With the scan tool, select View DTCs.Is the status Active for this DTC?YesGo to 6NoTest Complete.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)6. ENGINE CONTROL MODULE (ECM)Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Oxygen Sensor and the Engine Control Module (ECM).Look for any chafed, pierced, pinched, or partially broken wires.Look for broken, bent, pushed out or corroded terminals.Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.Look for the data to change or for the DTC to reset during the wiggle test.Refer to any Technical Service Bulletins that may apply.Were any problems found?YesRepair as necessary.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoReplace the Engine Control Module (ECM) in accordance with the Service Information.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)