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Home >> GMC >> 2000 >> Jimmy 2D Utility, RWD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 4.3L >> Diagnostic Tests >> DTC P0154: Heated Oxygen Sensor No. 1, Bank 2 - Insufficient Activity ("S" & "T" Series) >> Diagnostic Aids

Diagnostic Aids

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

With ignition on and engine off, HO2S 1 voltage on scan tool should gradually decrease to less than .15 volt indicating heater is operating properly. If voltage does not decrease as specified, disconnect HO2S 1 harness connector and connect a test light between HO2S 1 harness connector terminals "C" and "D" (engine harness side). If test light illuminates, replace HO2S 1. If test light does not illuminate, repair open in HO2S 1 heater ground circuit or HO2S 1 ignition feed circuit.

Using scan tool, monitor signal voltage while wiggling HO2S 1 related connectors and wiring harness with a warm engine running at part throttle in closed loop. If a failure is induced, signal voltage will change from normal fluctuating voltage of greater than .6 volt and less than .3 volt, to a fixed voltage of about .45 volt. A change in voltage will assist in isolating location of fault. DO NOT solder HO2S 1 wires.

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