B1331

Code

Other B — Body

Decklid Ajar Rear Door Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 45 EN: 67 RU: 50

AI status

Completed

ready

Completed 100%

Page language: EN

Read and record freeze-frame and all stored codes with a scan tool; note whether code is current or historic
Visually inspect decklid latch, switch and wiring harness near hinge for abrasion, broken wires, kinks or rod/pin interference
Inspect connector pins for corrosion, bending or pushed-out terminals; disconnect, inspect, and reconnect firmly
Check for signs of water intrusion in the decklid area and connectors
Verify related fuses and ground points are secure and corrosion-free
Wiggle the decklid wiring while observing the scan tool/live data for intermittent changes

Typical switch types: simple mechanical switch (open/closed) or open-drain signal to BCM. Expected states (generic): - Decklid closed: circuit closed to ground or low-voltage TTL level (often ~0–0.5 V) or continuity (near 0 Ω) - Decklid open: circuit open or pulled to reference voltage (often ~5–12 V) or high resistance (>>10 kΩ)
If switch is open/ground-switched: measure continuity between switch terminal and chassis ground with decklid closed (near 0 Ω) and open with decklid open (OL/infinite)
If signal is a 5 V reference circuit: expect ~5 V when open and ~0 V when closed (verify with vehicle wiring diagram)
Note: exact voltages/polarity vary by make/model — always confirm with vehicle-specific wiring diagram or factory data

Use a scan tool to confirm B1331, note whether code is pending or confirmed, and check for related codes (BCM, door modules).
Reproduce symptom: observe trunk open/closed status with scan tool while manually operating the latch and closing decklid slowly. Note any toggling or delays.
Visually inspect latch assembly, wiring at hinge, and connectors for damage, corrosion, or water. Repair obvious physical damage.
Check fuse(s) and main ground(s) for the BCM/trunk circuit; clean and tighten as needed.
Backprobe the decklid ajar switch connector (or harness connector at body) and measure voltage/continuity with decklid open and closed. Compare to expected states (see signal_params).
If intermittent, perform a wiggle test on the harness while observing live data; isolate the area where the signal changes.
If the switch wiring shows open/short/erratic behavior, trace and repair wiring (repair harness, replace grommet, solder/use heat shrink, or replace connector).
If wiring and switch test good, replace latch/ajar switch assembly and retest.
If switch and wiring are confirmed good and connector/ground are clean, consider BCM input fault — confirm with manufacturer procedures before replacing BCM.
Clear codes and retest operation over several open/close cycles and a short road/test period to verify repair.