B1326

Code

Other B — Body

Door Ajar Lamp Circuit Short To Ground

Brand: Other

Type: B — Body

Views: UK: 32 EN: 67 RU: 50

AI status

Completed

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Page language: EN

Causes

Chafed or pinched wiring contacting chassis ground
Corroded or damaged connector at the lamp or BCM
Failed lamp assembly or LED driver with internal short
Water intrusion into harness or lamp housing
Aftermarket equipment or previous repair damage
Faulty BCM or driver transistor (less common)

Symptoms

Door ajar lamp may be stuck on or not functioning
Interior warning or chime indicating door ajar even with doors closed
Blown fuse on the lighting or BCM circuit
Parasitic battery drain when vehicle is off
Intermittent operation or changes with door movement (hinge area)

What to check

Scan for B1326 and any related codes; record freeze-frame data and ignition state
Visual inspection of lamp, connector, and wiring routing (door jamb, hinge, body seams)
Check relevant fuses for blown condition and fuse holder corrosion
Measure voltage at the lamp connector with ignition on and while commanding lamp
Measure resistance/continuity from lamp circuit to chassis ground with harness disconnected
Wiggle test wiring while watching live data or lamp function to reproduce fault

Signal parameters

With circuit good: high resistance to chassis ground (open) when lamp not powered
With circuit shorted: near 0 ohms or
Voltage at lamp connector: near battery voltage when power feed present; unexpected low voltage (near 0 V) indicates short to ground
Current draw: elevated when lamp circuit is shorted (may blow a fuse or trigger BCM protection)

Diagnostic algorithm

Confirm B1326 is current or stored and note any related DTCs; clear codes then attempt to re-create fault to verify.
Perform visual inspection of lamp assembly, connector, and harness routing through door hinge, sill, and body panels. Look for chafing, deformation, or corrosion.
Disconnect the door-ajar lamp connector. Measure resistance between the lamp circuit pin and chassis ground. A low resistance indicates a short in the harness or downstream component.
If the lamp assembly is disconnected and the short remains, isolate by disconnecting sections of the harness or unplugging the BCM input to find which section shows the short.
If short disappears when connector is unplugged at the lamp, bench-test or replace the lamp/LED module and inspect its connector for corrosion or water intrusion.
If short remains in harness, visually inspect and repair damaged wire insulation, reroute away from sharp edges, and repair/replace corroded connectors. Use heat-shrink tubing and proper terminals.
If harness and lamp test good, test the BCM output/input for internal short to ground using manufacturer procedure; replace BCM only after confirming external circuit integrity.
After repairs, reconnect, clear codes, and perform functional test: open/close doors, verify lamp behavior, and re-scan to ensure B1326 does not return.

Likely causes

Wire insulation rubbed through where harness passes through a body panel or door hinge
Connector pins corroded or bent causing short when mated
Lamp module/LED driver failed internally and is shorting to ground
Harness routed too close to sharp metal edge or screw
Ground strap or body ground point contamination causing incorrect return path

Fault status

⚠️ Status

BCM reports door-ajar lamp circuit has an unintended short to chassis ground (low resistance). Investigate wiring, lamp assembly, connectors, and BCM driver.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2 hours