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Home / DTC / B1525 — Remote unlock circuit short to positive

B1525 — Remote unlock circuit short to positive

Detailed page for trouble code B1525.

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22,491specific
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Code

B1525

ALFA ROMEO B — Body

Remote unlock circuit short to positive

Brand: ALFA ROMEO
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Shorted unlock output wire to battery positive (B+)
  • Stuck or welded relay contact feeding the unlock output
  • Faulty door lock actuator with internal short
  • Corroded or damaged connector causing high voltage feed into output
  • Body Control Module (BCM) internal fault
  • Aftermarket alarm/keyless entry wiring error

Symptoms

  • Remote/key fob unlock does not work or works intermittently
  • Fuse for locks blows repeatedly
  • Continuous battery drain when vehicle is off
  • Door(s) lock/unlock behave erratically or lock/unlock without command
  • Relevant BCM warnings or multiple body system faults stored

What to check

  • Read BCM/Body module codes and freeze frame data with a proper scan tool
  • Visually inspect wiring harnesses, connectors, and door actuator(s) for damage or corrosion
  • Check related fuses and relays for continuity and signs of melting or failure
  • Measure voltage at the unlock output terminal with ignition off and while pressing remote
  • Disconnect the door actuator/unlock motor and try the unlock command to see if code clears
  • Inspect for aftermarket alarm or keyless entry modules and their wiring

Signal parameters

  • Normal idle: unlock output = open/high-impedance (no battery feed)
  • On unlock command: output expected = switched 12 V pulse (typically 0–1 A depending on actuator)
  • Fault condition: persistent ~12 V present at output when command not given (short to B+)
  • Resistance of unlock output to battery positive should be high (open); near 0 Ω indicates short

Diagnostic algorithm

  1. Connect a diagnostic scan tool, confirm B1525 and note any related codes or freeze-frame data.
  2. Clear codes, attempt remote unlock while monitoring the BCM unlock output voltage/waveform.
  3. Visually inspect the entire unlock circuit wiring from BCM to door actuators and connectors for abrasion, pinched spots, melted insulation, or corrosion.
  4. With battery disconnected, perform continuity/resistance check between the unlock output conductor and battery positive. A near-zero reading indicates a short to B+.
  5. Disconnect the unlock actuator(s) and any intermediate connectors; re-check if the code returns when performing unlock command. If code clears, suspect actuator or wiring in that branch.
  6. Check unlock relay (if fitted): remove and bench-test for stuck contacts or substitute known-good relay.
  7. If short persists with actuators disconnected, trace wiring harness and isolate sections using back-probing and a fused jumper to locate the shorted segment.
  8. Repair damaged wiring or connectors; replace faulty actuator or relay as required.
  9. If wiring and external components test good, suspect BCM output transistor failure—verify with manufacturer procedures and consider module replacement or reprogramming per service manual.
  10. After repair, clear codes and perform full function test (multiple lock/unlock cycles, power off soak) to confirm repair and no battery drain.

Likely causes

  • Pinched or chafed unlock wire contacting a constant 12V source
  • Failed remote unlock relay stuck closed
  • Door actuator motor shorted, connecting output directly to battery
  • Water intrusion at connector forcing a positive feed
  • Incorrectly installed aftermarket remote or alarm harness

Fault status

⚠️ Status
Remote unlock circuit short to positive detected. Unlock function may be disabled, fuses may blow, or battery drain may occur. Inspect wiring, actuator, relays, and BCM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

B1524 B1526 B1234 B1620 U1000
89

Browse 89 ALFA ROMEO manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

ALFA ROMEO

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Code

B1525

FIAT B — Body

Remote unlock circuit short to positive

Brand: FIAT
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Shorted unlock output wire to battery positive (B+)
  • Stuck or welded relay contact feeding the unlock output
  • Faulty door lock actuator with internal short
  • Corroded or damaged connector causing high voltage feed into output
  • Body Control Module (BCM) internal fault
  • Aftermarket alarm/keyless entry wiring error

Symptoms

  • Remote/key fob unlock does not work or works intermittently
  • Fuse for locks blows repeatedly
  • Continuous battery drain when vehicle is off
  • Door(s) lock/unlock behave erratically or lock/unlock without command
  • Relevant BCM warnings or multiple body system faults stored

What to check

  • Read BCM/Body module codes and freeze frame data with a proper scan tool
  • Visually inspect wiring harnesses, connectors, and door actuator(s) for damage or corrosion
  • Check related fuses and relays for continuity and signs of melting or failure
  • Measure voltage at the unlock output terminal with ignition off and while pressing remote
  • Disconnect the door actuator/unlock motor and try the unlock command to see if code clears
  • Inspect for aftermarket alarm or keyless entry modules and their wiring

Signal parameters

  • Normal idle: unlock output = open/high-impedance (no battery feed)
  • On unlock command: output expected = switched 12 V pulse (typically 0–1 A depending on actuator)
  • Fault condition: persistent ~12 V present at output when command not given (short to B+)
  • Resistance of unlock output to battery positive should be high (open); near 0 Ω indicates short

Diagnostic algorithm

  1. Connect a diagnostic scan tool, confirm B1525 and note any related codes or freeze-frame data.
  2. Clear codes, attempt remote unlock while monitoring the BCM unlock output voltage/waveform.
  3. Visually inspect the entire unlock circuit wiring from BCM to door actuators and connectors for abrasion, pinched spots, melted insulation, or corrosion.
  4. With battery disconnected, perform continuity/resistance check between the unlock output conductor and battery positive. A near-zero reading indicates a short to B+.
  5. Disconnect the unlock actuator(s) and any intermediate connectors; re-check if the code returns when performing unlock command. If code clears, suspect actuator or wiring in that branch.
  6. Check unlock relay (if fitted): remove and bench-test for stuck contacts or substitute known-good relay.
  7. If short persists with actuators disconnected, trace wiring harness and isolate sections using back-probing and a fused jumper to locate the shorted segment.
  8. Repair damaged wiring or connectors; replace faulty actuator or relay as required.
  9. If wiring and external components test good, suspect BCM output transistor failure—verify with manufacturer procedures and consider module replacement or reprogramming per service manual.
  10. After repair, clear codes and perform full function test (multiple lock/unlock cycles, power off soak) to confirm repair and no battery drain.

Likely causes

  • Pinched or chafed unlock wire contacting a constant 12V source
  • Failed remote unlock relay stuck closed
  • Door actuator motor shorted, connecting output directly to battery
  • Water intrusion at connector forcing a positive feed
  • Incorrectly installed aftermarket remote or alarm harness

Fault status

⚠️ Status
Remote unlock circuit short to positive detected. Unlock function may be disabled, fuses may blow, or battery drain may occur. Inspect wiring, actuator, relays, and BCM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

B1524 B1526 B1234 B1620 U1000
Repair manuals

Manual library for FIAT

26

Browse 26 FIAT manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

FIAT

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Code

B1525

MITSUBISHI B — Body

DR.buckle SW SHT.to GND for N.O

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Shorted unlock output wire to battery positive (B+)
  • Stuck or welded relay contact feeding the unlock output
  • Faulty door lock actuator with internal short
  • Corroded or damaged connector causing high voltage feed into output
  • Body Control Module (BCM) internal fault
  • Aftermarket alarm/keyless entry wiring error

Symptoms

  • Remote/key fob unlock does not work or works intermittently
  • Fuse for locks blows repeatedly
  • Continuous battery drain when vehicle is off
  • Door(s) lock/unlock behave erratically or lock/unlock without command
  • Relevant BCM warnings or multiple body system faults stored

What to check

  • Read BCM/Body module codes and freeze frame data with a proper scan tool
  • Visually inspect wiring harnesses, connectors, and door actuator(s) for damage or corrosion
  • Check related fuses and relays for continuity and signs of melting or failure
  • Measure voltage at the unlock output terminal with ignition off and while pressing remote
  • Disconnect the door actuator/unlock motor and try the unlock command to see if code clears
  • Inspect for aftermarket alarm or keyless entry modules and their wiring

Signal parameters

  • Normal idle: unlock output = open/high-impedance (no battery feed)
  • On unlock command: output expected = switched 12 V pulse (typically 0–1 A depending on actuator)
  • Fault condition: persistent ~12 V present at output when command not given (short to B+)
  • Resistance of unlock output to battery positive should be high (open); near 0 Ω indicates short

Diagnostic algorithm

  1. Connect a diagnostic scan tool, confirm B1525 and note any related codes or freeze-frame data.
  2. Clear codes, attempt remote unlock while monitoring the BCM unlock output voltage/waveform.
  3. Visually inspect the entire unlock circuit wiring from BCM to door actuators and connectors for abrasion, pinched spots, melted insulation, or corrosion.
  4. With battery disconnected, perform continuity/resistance check between the unlock output conductor and battery positive. A near-zero reading indicates a short to B+.
  5. Disconnect the unlock actuator(s) and any intermediate connectors; re-check if the code returns when performing unlock command. If code clears, suspect actuator or wiring in that branch.
  6. Check unlock relay (if fitted): remove and bench-test for stuck contacts or substitute known-good relay.
  7. If short persists with actuators disconnected, trace wiring harness and isolate sections using back-probing and a fused jumper to locate the shorted segment.
  8. Repair damaged wiring or connectors; replace faulty actuator or relay as required.
  9. If wiring and external components test good, suspect BCM output transistor failure—verify with manufacturer procedures and consider module replacement or reprogramming per service manual.
  10. After repair, clear codes and perform full function test (multiple lock/unlock cycles, power off soak) to confirm repair and no battery drain.

Likely causes

  • Pinched or chafed unlock wire contacting a constant 12V source
  • Failed remote unlock relay stuck closed
  • Door actuator motor shorted, connecting output directly to battery
  • Water intrusion at connector forcing a positive feed
  • Incorrectly installed aftermarket remote or alarm harness

Fault status

⚠️ Status
Remote unlock circuit short to positive detected. Unlock function may be disabled, fuses may blow, or battery drain may occur. Inspect wiring, actuator, relays, and BCM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

B1524 B1526 B1234 B1620 U1000
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MITSUBISHI

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

B1525

Other B — Body

Keyless Entry Circuit Short To Battery

Brand: Other
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Shorted unlock output wire to battery positive (B+)
  • Stuck or welded relay contact feeding the unlock output
  • Faulty door lock actuator with internal short
  • Corroded or damaged connector causing high voltage feed into output
  • Body Control Module (BCM) internal fault
  • Aftermarket alarm/keyless entry wiring error

Symptoms

  • Remote/key fob unlock does not work or works intermittently
  • Fuse for locks blows repeatedly
  • Continuous battery drain when vehicle is off
  • Door(s) lock/unlock behave erratically or lock/unlock without command
  • Relevant BCM warnings or multiple body system faults stored

What to check

  • Read BCM/Body module codes and freeze frame data with a proper scan tool
  • Visually inspect wiring harnesses, connectors, and door actuator(s) for damage or corrosion
  • Check related fuses and relays for continuity and signs of melting or failure
  • Measure voltage at the unlock output terminal with ignition off and while pressing remote
  • Disconnect the door actuator/unlock motor and try the unlock command to see if code clears
  • Inspect for aftermarket alarm or keyless entry modules and their wiring

Signal parameters

  • Normal idle: unlock output = open/high-impedance (no battery feed)
  • On unlock command: output expected = switched 12 V pulse (typically 0–1 A depending on actuator)
  • Fault condition: persistent ~12 V present at output when command not given (short to B+)
  • Resistance of unlock output to battery positive should be high (open); near 0 Ω indicates short

Diagnostic algorithm

  1. Connect a diagnostic scan tool, confirm B1525 and note any related codes or freeze-frame data.
  2. Clear codes, attempt remote unlock while monitoring the BCM unlock output voltage/waveform.
  3. Visually inspect the entire unlock circuit wiring from BCM to door actuators and connectors for abrasion, pinched spots, melted insulation, or corrosion.
  4. With battery disconnected, perform continuity/resistance check between the unlock output conductor and battery positive. A near-zero reading indicates a short to B+.
  5. Disconnect the unlock actuator(s) and any intermediate connectors; re-check if the code returns when performing unlock command. If code clears, suspect actuator or wiring in that branch.
  6. Check unlock relay (if fitted): remove and bench-test for stuck contacts or substitute known-good relay.
  7. If short persists with actuators disconnected, trace wiring harness and isolate sections using back-probing and a fused jumper to locate the shorted segment.
  8. Repair damaged wiring or connectors; replace faulty actuator or relay as required.
  9. If wiring and external components test good, suspect BCM output transistor failure—verify with manufacturer procedures and consider module replacement or reprogramming per service manual.
  10. After repair, clear codes and perform full function test (multiple lock/unlock cycles, power off soak) to confirm repair and no battery drain.

Likely causes

  • Pinched or chafed unlock wire contacting a constant 12V source
  • Failed remote unlock relay stuck closed
  • Door actuator motor shorted, connecting output directly to battery
  • Water intrusion at connector forcing a positive feed
  • Incorrectly installed aftermarket remote or alarm harness

Fault status

⚠️ Status
Remote unlock circuit short to positive detected. Unlock function may be disabled, fuses may blow, or battery drain may occur. Inspect wiring, actuator, relays, and BCM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.5 hours

Similar codes

B1524 B1526 B1234 B1620 U1000
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