Test NTC-10B: Checking Oxygen Sensor Switching
NOTE:
Perform TEST NTC-10A: CHECKING OXYGEN SENSOR SWITCHING before proceeding.
- Start engine. Allow engine to idle. Inspect engine for any abnormal vacuum conditions which may indicate a possible engine mechanical problem. If abnormal vacuum conditions are present, repair engine as necessary. Perform TEST VER-2A: ROAD TEST VERIFICATION . If abnormal vacuum conditions are not present, go to next step.
- Using scan tool, read O2S signal voltages. If O2S signal voltage is .10 volt or more for any O2S, go to step 4. If O2S signal voltage is less than .10 volt for any O2S, go to next step.
- Turn ignition off. Disconnect O2S connector that was less than .10 volt. See O2 SENSOR IDENTIFICATION table. Disconnect Powertrain Control Module (PCM) connector. Using an ohmmeter, check resistance of O2S signal circuit at O2S connector (harness side). See O2S CONNECTOR WIRE IDENTIFICATION (HARNESS SIDE) table. If resistance is less than 5 ohms, repair short to ground on O2S signal circuit. Perform TEST VER-2A: ROAD TEST VERIFICATION . If resistance is 5 ohms or more, replace O2S. Perform TEST VER-2A: ROAD TEST VERIFICATION .NOTE: During next step, observe downstream O2S voltage should switch slower than upstream O2S voltage.
- Turn engine off. Turn ignition on. Using scan tool, reset adaptive fuel memory. Start engine and idle for at least 3 minutes. Engine must reach normal operating temperature. Using scan tool, read O2S signal voltages. If O2S signal voltages are switching normally, O2 sensors are functioning normally. Test is complete. If O2S signal voltages are not switching normally, go to TEST NTC-11A: CHECKING OXYGEN SENSOR HEATER .
O2S CONNECTOR WIRE IDENTIFICATION (HARNESS SIDE)
| Application | Wire Color |
|---|---|
| O2S 1/1 Sensor Signal Circuit | Black/Dark Green |
| O2S 1/2 Sensor Signal Circuit | Tan/White |
| O2S 2/1 Sensor Signal Circuit | Light Green/Red |
| O2S 2/2 Sensor Signal Circuit | Pink/White |