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P0174-FUEL SYSTEM 2/1 LEAN (CONTINUED) 9. O2 SENSOR SIGNAL CIRCUIT With the scan tool, monitor all the O2 Sensor voltage reading with the jumper wire removed. NOTE: The scan tool will display all O2 Sensor voltage readings approximately 5.0 volts when only one O2 NOTE: The scan tool will display one O2 Sensor voltage close to zero and the others will read lower than Is the voltage above 4.8 volts? Yes >> Go To 10 No >> Check all the O2 Signal circuits for a short to ground, open, or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 10. (K902) O2 RETURN UPSTREAM CIRCUIT Disconnect the 2/1 O2 Sensor harness connector. Measure the voltage on the (K902) O2 Return Upstream circuit in the Is the voltage at 2.5 volts? Yes >> Go To 11 No >> Check the (K902) O2 Return Upstream circuit for a short to ground, open, or short to voltage. Inspect the O2 Sen- Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 11. PCM NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal Were there any problems found? Yes >> Repair as necessary. Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) No >> Replace and program the Powertrain Control Module per Service Information. Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) 9 - 222 ENGINE ELECTRICAL DIAGNOSTICS ND |