B1605

Code

Other B — Body

Lamp Anti-Theft Indicator Circuit Short To Battery

Brand: Other

Type: B — Body

Views: UK: 28 EN: 43 RU: 34

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Page language: EN

Anti-theft/immobilizer lamp is ON continuously or behaves incorrectly
Related security system warnings or immobilizer faults
DTC stored in BCM or immobilizer module and possible lamp illumination when vehicle off
Blown fuse(s) protecting the lamp circuit (less common)
Parasitic battery drain in some cases

Scan for additional codes and read freeze/frame data
Visual inspection of dash harness, connectors, and any aftermarket alarm wiring
Inspect indicator lamp/bulb or LED assembly and its connector
Check related fuses and fusible links
Measure voltage at the lamp connector with ignition OFF and ON
Disconnect the lamp/indicator assembly and see if the code clears or lamp behavior changes

Circuit voltage (lamp connector): OFF state should be near 0 V (open) or module-controlled level; ON state should be ~11–14 V when commanded
Unexpected battery-level voltage (~12 V) on circuit when indicator is not commanded indicates short to battery
Typical indicator current draw: small — often
Continuity: open circuit to lamp when lamp removed; low resistance to battery positive indicates short

Retrieve stored codes and freeze frame. Note ignition/key position when code set.
Perform a visual inspection of dash harness, instrument cluster, BCM connectors, and any alarm/immobilizer aftermarket components.
With ignition OFF, measure voltage at the indicator lamp connector. If ~12 V present with lamp disconnected, suspect short to battery or BCM fault.
Disconnect the indicator lamp/LED assembly. Clear codes and cycle ignition. If code does not return, suspect the lamp assembly or wiring near it.
If code persists with lamp disconnected, unplug BCM/immobilizer module connector (if service manual allows) and check if code clears. If code clears when module disconnected, module or internal driver likely at fault — proceed per service manual.
Use an ohmmeter to check for continuity between the lamp circuit and battery positive with ignition OFF and battery disconnected to avoid damage. Trace wiring to locate chafe or aftermarket tap.
Wiggle test harness while monitoring voltage or scanning for code set to locate intermittent shorts.
Repair chafed wires, replace damaged connectors, remove incorrect aftermarket splices, or replace faulty indicator lamp assembly as required.
If wiring and lamp are good, follow module-level diagnostics: perform module power/ground checks and consider BCM replacement only after confirming external wiring is correct.
After repair, clear codes and verify repair by cycling ignition and confirming code does not return and lamp behavior is correct.

Chafed wiring contacting a hot lead or fused accessory circuit near dash/steering column
Aftermarket alarm wiring connected incorrectly to the indicator circuit
Damaged connector at the instrument cluster or BCM
Failed instrument cluster lamp or LED assembly with internal short
BCM output transistor has failed and is sourcing current