B1566

Step 1: Perform visual inspection of all door jamb switches and wiring at each door, especially in hinge areas. Look for damaged insulation, exposed copper wire, corrosion, or signs of water intrusion. Check for proper switch operation by manually pressing each switch.

Step 2: Using a digital multimeter, disconnect the door ajar switch connector suspected and measure resistance between the switch signal wire and ground with switch both open and closed. Should read open circuit (infinite resistance) when door is closed and continuity when pressed. A constant short to ground (0-5 ohms) indicates faulty switch.

Step 3: If switch tests good, disconnect BCM connector and measure resistance from door ajar circuit wire at BCM harness side to chassis ground with switch disconnected. Should read infinite resistance; low resistance indicates wiring harness short to ground between switch and BCM.

Step 4: Inspect door hinge area wiring closely by flexing harness while monitoring resistance. Wiggle test door boot wiring between door and body pillar as this is common failure point. Check for wire pinched in door striker or latch mechanism.

Step 5: After repair, reconnect all components, clear codes, and cycle each door open and closed multiple times. Verify interior lights and door ajar warning function correctly and code does not return. Test with vehicle locked and alarm armed if equipped.