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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 110 (Diagnosis - VT25-E) >> Diagnostic Tests >> DTC P0723: OSS Intermittent >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Saturn Vue and 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Drive vehicle or rotate front wheels greater than 3 MPH. Using scan tool, monitor OSS. Is scan tool reading a consistent value? If so, problem is intermittent. See DIAGNOSTIC AIDS  . If not, go to next step.
  2. Turn ignition off. Disconnect transaxle 20-way harness connector. Turn ignition on, engine off. Measure voltage at transaxle 20-way harness connector terminal No. 4, then at terminal No. 5. Is voltage present on either circuit? If so, go to next step. If not, go to step  4 .
  3. Repair short to voltage in OSS high (400) and/or low (401) circuit.
  4. Turn ignition off. Inspect for corrosion in transaxle 20-way harness connector. Repair as necessary. Reconnect transaxle 20-way harness connector. Start engine. Wiggle connections between transaxle and TCM while monitoring OSS on the scan tool. Was problem found? If so, repair wiring or connection. If not, go to next step.
  5. Inspect the following possible causes and repair as necessary:
    • Loose sensor or air gap too large.
    • Leadframe to OSS sensor harness damaged, replace OSS.
    • Faulty leadframe has a short or open, replace control solenoid valve assembly.
    • Cracked OSS, replace OSS.
    • Check for loose terminal connections at TCM. Repair as necessary. If okay, replace TCM. See TRANSAXLE CONTROL MODULE  under REMOVAL & INSTALLATION.
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