Diagnostic Procedures
- If QUICK TEST was not performed, go to QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed, go to next step.
- Inspect HO2S Harness Connectors
Visually inspect vehicle front HO2S harness connector(s) (P1128) or rear HO2S harness connector(s) (P1129) for any indication of being crossed (stretched wires, wire harnesses not mounted properly). If there are no crossed connections or wires, go to next step. If there are any crossed connections or wires, repair as necessary. See WIRING DIAGRAMS article. After repair, go to step 4. - Verify Proper HO2S SIG PIN Location
Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure. For DTC P1128, disconnect both front HO2Ss from vehicle harness connectors.- HO2S-11 (Front Bank 1) = breakout box terminal No. 60.
- HO2S-21 (Front Bank 2) = breakout box terminal No. 87.
For P1129, disconnect both rear HO2Ss from vehicle harness connectors.
- HO2S-12 (Rear Bank 1) = breakout box terminal No. 35.
- HO2S-22 (Rear Bank 2) = breakout box terminal No. 60.
Measure resistance of HO2S signal circuits between appropriate breakout box terminals and HO2S 4-pin harness connector. If resistance reading is more than 5.0 ohms, go to next step. If resistance reading is less than 5.0 ohms, problem is intermittent. Refer to INTERMITTENT testing under SYSTEM TESTS .
- Verify Trouble Shooting Of DTCs Completed
Reconnect all disconnected connectors. Clear DTCs from PCM memory using scan tool. Perform QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If same DTC is present, replace faulty PCM. Repeat QUICK TEST under SELF-DIAGNOSTIC SYSTEM. If same DTC is not present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, trouble shooting is complete.