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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 102 (Engine Controls - Self-Diagnostics - 3.5L) >> Diagnostic Tests >> DTC P1639: 5-Volt Reference "B" Circuit >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue and 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Use Connector Test Adapter Kit (J-35616-A) for any test that requires probing the PCM harness connectors, electrical center fuse/relay cavities, component terminals and component harness connector. Using this kit will prevent damage caused by improper probing of connector terminals.

Check PCM connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connections. Check for damaged wiring harness. If wiring harness appears to be okay, observe A/C pressure sensor display on scan tool. With ignition on, wiggle connectors and wiring harnesses related to FTP sensor and A/C pressure sensor. A change in A/C pressure sensor display will indicate location of malfunction. Reviewing failure records vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to set occurs. This may assist in diagnosing the condition.