Powertrain Controls - ECM/PCM

Diagnostic Chart:

Electrical Schematic:

CIRCUIT DESCRIPTION
The Heated Oxygen Sensor (HO2S) produces a voltage that varies between 0.1V and 0.9V under normal operating conditions. The Engine Control Module (ECM) monitors this voltage and determines if the exhaust is lean or rich. If the voltage input at the ECM is about 0.1V, the exhaust is lean, and if the voltage input is about 0.9V the exhaust is rich. The HO2S has a built-in heater that keeps the HO2S at operating temperature while the engine is running.

Diagnostic Trouble Code (DTC) 13 will set if the following conditions are met for longer than 30 seconds continuously and the Analog to Digital (A/D) conversion value of the HO2S output voltage does not exceed 0.45 volts.
- Engine operating temperature greater than or equal to 70°C (158°F).
- Engine RPM greater than or equal to 2100 RPM.
- Hasn't achieved fuel cut mode.
- Charging efficiency greater than or equal to 38%.

CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This checks for HO2S voltage activity.
2. This checks for an open in GRY/YEL wire between ECM and HO2S or for a faulty ECM.
3. This checks for a short to voltage in YEL/BLU wire between ECM and HO2S, a faulty ECM or HO2S.
4. This checks for an open or a short to ground in YEL/BLU wire between ECM and HO2S, a faulty ECM or HO2S.

DIAGNOSTIC AIDS
Normal voltage on the HO2S input wire varies between 100 mV and 900 mV (0.1 and 0.9 volt), while in "Closed Loop." Refer to Oxygen Sensor for additional information. Oxygen Sensor

INTERMITTENT MALFUNCTIONS
An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection before component replacement.