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Home >> Cadillac >> 1991 >> DeVille Base, 4D Sedan >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Self-Diagnostic System Check >> Chart A-1, Inoperative Service Air COND Light >> Test Procedures

Test Procedures

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. If the SERVICE AIR COND light does not illuminate with ignition on and display shows "c", "d" or "-151", the BCM's microprocessor is not functioning properly, which can be due to improper PROM insertion or faulty components in the BCM.
  2. If the SERVICE AIR COND light will not illuminate when grounding circuit No. 721, bulb circuitry is faulty.
  3. If the SERVICE AIR COND light turns on, check battery, ignition and ground circuit to the BCM for integrity. If circuit is okay, check BCM connector or for a faulty BCM.
Fig 1: Chart A-1, Schematic, Inoperative Service Air Cond Light
G91C07682
Fig 2: Flow Chart A-1, Inoperative Service Air Cond Light
G91E07683
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