Test TC-125A - Right Downstream O2 Sensor Heater Failure
NOTE:
For connector terminal ID, see CONNECTOR IDENTIFICATION Directory. For wiring diagram, see WIRING DIAGRAMS
article.
- Disconnect right downstream O2 sensor connector. Allow O2 sensor to cool to room temperature before checking resistance. Using an external ohmmeter, measure resistance between ASD relay output circuit and heater ground circuit (between 2 White wires) at right downstream O2 sensor connector (component side). See RIGHT DOWNSTREAM O2 SENSOR CONNECTOR WIRE IDENTIFICATION (COMPONENT SIDE) table. If resistance is 4-6 ohms, go to next step. If resistance is not 4-6 ohms, replace right downstream O2 sensor. Perform TEST VER-5A.
- Using scan tool in ohmmeter mode, check resistance of right downstream O2 sensor heater ground circuit at right downstream O2 sensor connector (harness side). See RIGHT DOWNSTREAM O2 SENSOR CONNECTOR WIRE IDENTIFICATION (HARNESS SIDE) table. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open heater ground circuit. Perform TEST VER-5A.
- Start engine. Using scan tool in voltmeter mode, check voltage of sensor ground circuit at right downstream O2 sensor connector (harness side). See RIGHT DOWNSTREAM O2 SENSOR CONNECTOR WIRE IDENTIFICATION (HARNESS SIDE) table. If voltage is 5 volts or less, go to next step. If voltage is more than 5 volts, repair short to voltage on sensor ground circuit. Perform TEST VER-5A.
- With engine running, using scan tool in voltmeter mode, check voltage of ASD relay output circuit at right downstream O2 sensor connector (harness side). See RIGHT DOWNSTREAM O2 SENSOR CONNECTOR WIRE IDENTIFICATION (HARNESS SIDE) table. If voltage is less than 12 volts, repair open ASD relay output circuit. Perform TEST VER-5A. If voltage is 12 volts or more, replace right downstream O2 sensor. Perform TEST VER-5A.
RIGHT DOWNSTREAM O2 SENSOR CONNECTOR WIRE ID (HARNESS SIDE)
| Application | Wire Color |
|---|---|
| O2 Sensor Signal Circuit | White/Dark Green |
| O2 Sensor ASD Relay Output Circuit | Black/Red |
| O2 Sensor Heater Ground Circuit | Black |
| O2 Sensor Ground Circuit | Black/Green |
RIGHT DOWNSTREAM O2 SENSOR CONNECTOR WIRE ID (COMPONENT SIDE)
| Application | Wire Color |
|---|---|
| O2 Sensor Signal Circuit | Black |
| O2 Sensor ASD Relay Output Circuit | White |
| O2 Sensor Heater Ground Circuit | White |
| O2 Sensor Ground Circuit | Gray |