B1215

Code

ALFA ROMEO B — Body

Platform lights short to positive

Brand: ALFA ROMEO

Type: B — Body

Views: UK: 6 EN: 12 RU: 8

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged wiring insulation contacting chassis or constant B+ conductor
Corroded or damaged lamp connector or socket
Faulty LED/bulb module with internal short to B+
Defective lighting control module / body control module (BCM)
Aftermarket equipment or poor previous repair creating a short
Water ingress in lamp assembly or connector

Symptoms

Platform/interior lights remain on or operate intermittently
Associated warning lights or messages on dash (interior lamp fault)
Fuses related to interior lighting may blow or show heat damage
Battery drain with lights apparently off
DTC B1215 stored in memory; possible other related body codes

What to check

Scan vehicle and record DTCs and freeze-frame data; clear and re-scan to confirm
Visually inspect lamp assemblies, connectors and wiring for corrosion, damage, or water
Check related fuse(s) for continuity and correct rating
With lamp removed, check connector pin voltages with key on and lights off/on
Unplug the platform light module and see if code clears or symptoms change
Wiggle harnesses at hinges and door sills while monitoring for changes

Signal parameters

Expected: Lamp circuit (return side) near 0 V with lights off; ~battery voltage (~12–14 V) when lamp circuit commanded on
Fault condition: Circuit shows constant battery voltage (≈12 V) when it should be low — indicates short to positive
Resistance: Open-circuit or high ohms when connector unplugged to ground; short to B+ will show low resistance to battery positive
Module output: BCM-driven output should switch between ground and open; if stuck to B+ the module output may read constant high

Diagnostic algorithm

Read and record all body/lighting DTCs. Note conditions (ignition state, lamp state).
Visually inspect platform light, mounting, connector and wiring for obvious damage or corrosion. Repair any visible issues and retest.
Disconnect the platform light/LED assembly. Clear codes, cycle ignition/lights and see if B1215 returns. If code does not return, suspect lamp assembly or connector.
With connector unplugged, measure voltage between the circuit pin and ground. If battery voltage is present with lights off, there is a short to B+ downstream of the connector or the BCM output is stuck.
Measure resistance from the circuit pin to battery positive with ignition off. Low resistance indicates short to B+. Isolate sections by disconnecting nearby connectors and re-measuring until the shorted section is found.
Inspect/replace damaged wiring, repair chafed insulation, and replace corroded connectors or lamp assemblies as needed. Use proper sealing for water intrusion areas.
If wiring and lamp assembly check good, test the BCM output. Verify correct switching behavior per service manual; if BCM output is defective after harness/isolation checks, replace or reprogram per manufacturer procedure.
After repair, clear codes and perform functional test and battery drain test if needed to confirm repair.

Likely causes

Short in harness near the platform light or under-door area where route is exposed
Connector corrosion allowing positive feed to short onto lamp return
Failed LED interior lamp with internal electronics shorted to battery
Damaged insulation from pinch point (door hinge, trunk lid) contacting constant 12 V
Faulty BCM output transistor stuck high

Fault status

⚠️ Status

Stored fault — platform/interior lights circuit detected a short to positive (B+). Lamp circuit voltage remains at battery level when it should be switched; body control module flagged the condition.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5 - 2.0 hours

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