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Home >> Chevrolet >> 2001 >> Impala Police >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P1639: 5-Volt Reference Circuit "B" Or No. 2 (Grand PRIX, LESABRE & Park Avenue) >> Diagnostic Aids

Diagnostic Aids

Check for faulty connections or damaged harness. Observe scan tool A/C PRESSURE display while moving harness and connectors related to A/C refrigerant pressure sensor. A change in scan tool display indicates fault location.

Reviewing freeze frame/failure records will indicate vehicle mileage since diagnostic test last failed. This may help determine how often condition that caused DTC to be set occurs. This may assist in diagnosing condition.