B1C26

Code

Generic B — Body

Body Control Module: Door Ajar Circuit Short to Ground

Brand: Generic

Type: B — Body

Views: UK: 16 EN: 26 RU: 13

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged/chafed wiring harness at door hinge, body-to-door rub points or pinched areas
Corroded, bent or pushed‑out connector pins at door switch or BCM
Faulty door ajar (door switch) or striker sensor with internal short to ground
Water intrusion or corrosion in switch or connector causing grounding
Aftermarket alarm, lighting or wiring tied into door circuits creating a short
Poor or missing ground/shorted splice in harness

Symptoms

Door ajar lamp or message illuminated continuously for one door or multiple doors
Interior/courtesy lamps stay on or behave erratically
False open/close warnings, chimes or locking behavior
Battery drain if lamps remain on for an extended period
Intermittent operation that may change when moving/closing doors or flexing harness

What to check

Read freeze frame and DTC with a scan tool; record door status data and any related codes
Operate each door while observing live data for door switch inputs (open/closed)
Visual inspection of wiring at door hinge areas, door jambs and connectors for chafing, corrosion or damage
Disconnect door switch connectors one at a time; check whether code or door-open indication clears
Backprobe the door-ajar circuit at the switch and at the BCM to compare voltages and behavior when door is opened/closed
Measure resistance from the door-ajar circuit to chassis ground with the connector disconnected to verify presence of an unexpected short

Signal parameters

Normal: switch open = pulled up by BCM to ~9–12 V (varies by vehicle); switch closed = near 0 V (ground)
Resistance: open circuit = high resistance (kΩ to OL); closed = near 0 Ω to ground
Short to ground condition: circuit voltage at connector or BCM pin near 0 V when switch should be open
Current draw: door switch circuits are low current; significant current when switch open indicates a short or load

Diagnostic algorithm

Connect scan tool and confirm B1C26 is current. Note which door(s) reported and freeze frame data. Clear code and see if it returns.
With ignition ON, monitor live data for all door-ajar inputs while opening/closing each door to identify which input behaves incorrectly.
Visually inspect door harnesses, grommets and connectors for damage, corrosion or water; repair obvious faults.
Disconnect the suspect door switch connector. If code clears and door status changes, isolate the short to the door harness or switch. If it does not clear, suspect harness upstream or BCM.
With the switch connector disconnected, measure resistance between the door-ajar circuit wire and chassis ground. Low resistance indicates a short to ground in the harness or an accessory tied in.
Backprobe at the BCM input pin (or harness connector at the body junction) and check voltage: should be pulled up when switch open and near 0 V when closed. Trace wiring toward the short when the voltage stays near 0 V.
Inspect and repair damaged wiring (splice, repair or replace affected section). Clean or replace corroded connectors and switches. Protect repairs with grommets and routing away from hinge pinch points.
If wiring and switch check good, bench-test/replace the door-ajar switch. Re-check for code.
If fault persists after harness and switch verified repaired, suspect BCM internal fault. Verify power/grounds to BCM and consult manufacturer procedures for BCM testing, reprogramming or replacement.
After repair, clear codes and perform full system verification including door operation, lamp behavior and re-scan for DTCs.

Likely causes

Chafed wiring at hinge/door jamb
Corroded door switch connector
Faulty door ajar switch
Water intrusion in door connector or switch

Fault status

⚠️ Status

Short to ground detected on Body Control Module door-ajar input circuit. Module reports circuit pulled to ground when it should be open or pulled up. May cause door-ajar indicator or interior lights to be incorrect.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours