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Home / DTC / B1300 — Door electric locking relay coil circuit

B1300 — Door electric locking relay coil circuit

Detailed page for trouble code B1300.

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22,491specific
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Code

B1300

ALFA ROMEO B — Body

Door electric locking relay coil circuit

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

Causes

  • Open or short in relay coil supply or return wiring
  • Corroded, loose or damaged relay connector or socket
  • Faulty door lock relay (coil open/short or intermittent)
  • Blown fuse or poor fuse connection in relay supply circuit
  • Poor ground or battery supply to relay/BCM
  • Body Control Module (BCM) output driver fault or software error

Symptoms

  • Central locking does not operate or operates intermittently
  • No audible relay click when locking/unlocking
  • Only some doors lock/unlock
  • Dashboard message or indicator about central locking error
  • Parasitic battery drain (rare) or fuse blowing
  • Remote key fob locking/unlocking ineffective or inconsistent

What to check

  • Read stored and pending codes with a diagnostic scanner; check BCM for related body/CAN errors
  • Visually inspect relay, relay socket, fuses and associated connectors for corrosion, heat damage or loose pins
  • Check fuse continuity and supply voltage to relay fuse
  • Listen for relay click while commanding locks from scanner or key fob
  • Measure voltage at relay coil supply and control pins during lock/unlock command
  • Measure coil resistance (relay removed) and compare with expected range

Signal parameters

  • Relay coil supply voltage (key ON): typically battery voltage ≈ 12 V
  • Control signal when activating: BCM usually grounds coil — control pin should go to ~0 V when active; inactive ≈ 12 V
  • Typical relay coil resistance: approx. 60–200 ohms (manufacturer-dependent) — expect coil current roughly 60–200 mA at 12 V
  • Activation duration: brief pulses during lock/unlock (usually < 2 seconds)
  • Fuse rating: check vehicle-specific manual (commonly 7.5 A–20 A for body circuits)

Diagnostic algorithm

  1. Confirm B1300 is current or stored; note freeze-frame and related codes from BCM.
  2. Visual inspection: check relay, socket, fuses and wiring for corrosion, damage or water ingress. Repair obvious issues.
  3. With key ON, command lock/unlock while listening for relay. If no click, proceed to electrical checks.
  4. Check fuse supplying the relay for continuity and battery voltage at both sides of the fuse.
  5. Remove relay and measure coil resistance across coil pins on the relay. If outside expected range, replace relay.
  6. With relay removed, measure supply voltage at the relay supply terminal (should be ~12 V) and monitor the control terminal while commanding locks. Control should switch to ~0 V (or change state) when activated.
  7. If supply present but no control change, backprobe connector and test continuity between BCM output and relay socket; check for shorts to battery or ground.
  8. If wiring and connectors are good and BCM output does not change, inspect BCM grounds and power. If BCM output is confirmed faulty, consider BCM repair/replacement and check for software updates.
  9. If intermittent, perform wiggle tests on harnesses while operating locks; repair broken wires or poor crimps with solder or proper connectors.
  10. After repair, clear codes and test multiple lock/unlock cycles; confirm no new B1300 or related codes appear.

Likely causes

  • Faulty relay or relay socket (most common)
  • Wiring/connectors to relay open or corroded
  • Blown fuse or poor supply to the relay
  • BCM driver fault (less common) or intermittent grounding
  • Aftermarket alarm or actuator causing short/overload

Fault status

⚠️ Status
Door electric locking relay coil circuit fault — open/short or relay/BCM drive issue detected.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2 hours

Similar codes

B1301 B1310 B1234 B1600 U0100
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

B1300

FIAT B — Body

Door electric locking relay coil circuit

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

Causes

  • Open or short in relay coil supply or return wiring
  • Corroded, loose or damaged relay connector or socket
  • Faulty door lock relay (coil open/short or intermittent)
  • Blown fuse or poor fuse connection in relay supply circuit
  • Poor ground or battery supply to relay/BCM
  • Body Control Module (BCM) output driver fault or software error

Symptoms

  • Central locking does not operate or operates intermittently
  • No audible relay click when locking/unlocking
  • Only some doors lock/unlock
  • Dashboard message or indicator about central locking error
  • Parasitic battery drain (rare) or fuse blowing
  • Remote key fob locking/unlocking ineffective or inconsistent

What to check

  • Read stored and pending codes with a diagnostic scanner; check BCM for related body/CAN errors
  • Visually inspect relay, relay socket, fuses and associated connectors for corrosion, heat damage or loose pins
  • Check fuse continuity and supply voltage to relay fuse
  • Listen for relay click while commanding locks from scanner or key fob
  • Measure voltage at relay coil supply and control pins during lock/unlock command
  • Measure coil resistance (relay removed) and compare with expected range

Signal parameters

  • Relay coil supply voltage (key ON): typically battery voltage ≈ 12 V
  • Control signal when activating: BCM usually grounds coil — control pin should go to ~0 V when active; inactive ≈ 12 V
  • Typical relay coil resistance: approx. 60–200 ohms (manufacturer-dependent) — expect coil current roughly 60–200 mA at 12 V
  • Activation duration: brief pulses during lock/unlock (usually < 2 seconds)
  • Fuse rating: check vehicle-specific manual (commonly 7.5 A–20 A for body circuits)

Diagnostic algorithm

  1. Confirm B1300 is current or stored; note freeze-frame and related codes from BCM.
  2. Visual inspection: check relay, socket, fuses and wiring for corrosion, damage or water ingress. Repair obvious issues.
  3. With key ON, command lock/unlock while listening for relay. If no click, proceed to electrical checks.
  4. Check fuse supplying the relay for continuity and battery voltage at both sides of the fuse.
  5. Remove relay and measure coil resistance across coil pins on the relay. If outside expected range, replace relay.
  6. With relay removed, measure supply voltage at the relay supply terminal (should be ~12 V) and monitor the control terminal while commanding locks. Control should switch to ~0 V (or change state) when activated.
  7. If supply present but no control change, backprobe connector and test continuity between BCM output and relay socket; check for shorts to battery or ground.
  8. If wiring and connectors are good and BCM output does not change, inspect BCM grounds and power. If BCM output is confirmed faulty, consider BCM repair/replacement and check for software updates.
  9. If intermittent, perform wiggle tests on harnesses while operating locks; repair broken wires or poor crimps with solder or proper connectors.
  10. After repair, clear codes and test multiple lock/unlock cycles; confirm no new B1300 or related codes appear.

Likely causes

  • Faulty relay or relay socket (most common)
  • Wiring/connectors to relay open or corroded
  • Blown fuse or poor supply to the relay
  • BCM driver fault (less common) or intermittent grounding
  • Aftermarket alarm or actuator causing short/overload

Fault status

⚠️ Status
Door electric locking relay coil circuit fault — open/short or relay/BCM drive issue detected.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2 hours

Similar codes

B1301 B1310 B1234 B1600 U0100
Repair manuals

Manual library for FIAT

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Code

B1300

LAND ROVER B — Body

Electric door lock - circuit failure

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

Causes

  • Open or short in relay coil supply or return wiring
  • Corroded, loose or damaged relay connector or socket
  • Faulty door lock relay (coil open/short or intermittent)
  • Blown fuse or poor fuse connection in relay supply circuit
  • Poor ground or battery supply to relay/BCM
  • Body Control Module (BCM) output driver fault or software error

Symptoms

  • Central locking does not operate or operates intermittently
  • No audible relay click when locking/unlocking
  • Only some doors lock/unlock
  • Dashboard message or indicator about central locking error
  • Parasitic battery drain (rare) or fuse blowing
  • Remote key fob locking/unlocking ineffective or inconsistent

What to check

  • Read stored and pending codes with a diagnostic scanner; check BCM for related body/CAN errors
  • Visually inspect relay, relay socket, fuses and associated connectors for corrosion, heat damage or loose pins
  • Check fuse continuity and supply voltage to relay fuse
  • Listen for relay click while commanding locks from scanner or key fob
  • Measure voltage at relay coil supply and control pins during lock/unlock command
  • Measure coil resistance (relay removed) and compare with expected range

Signal parameters

  • Relay coil supply voltage (key ON): typically battery voltage ≈ 12 V
  • Control signal when activating: BCM usually grounds coil — control pin should go to ~0 V when active; inactive ≈ 12 V
  • Typical relay coil resistance: approx. 60–200 ohms (manufacturer-dependent) — expect coil current roughly 60–200 mA at 12 V
  • Activation duration: brief pulses during lock/unlock (usually < 2 seconds)
  • Fuse rating: check vehicle-specific manual (commonly 7.5 A–20 A for body circuits)

Diagnostic algorithm

  1. Confirm B1300 is current or stored; note freeze-frame and related codes from BCM.
  2. Visual inspection: check relay, socket, fuses and wiring for corrosion, damage or water ingress. Repair obvious issues.
  3. With key ON, command lock/unlock while listening for relay. If no click, proceed to electrical checks.
  4. Check fuse supplying the relay for continuity and battery voltage at both sides of the fuse.
  5. Remove relay and measure coil resistance across coil pins on the relay. If outside expected range, replace relay.
  6. With relay removed, measure supply voltage at the relay supply terminal (should be ~12 V) and monitor the control terminal while commanding locks. Control should switch to ~0 V (or change state) when activated.
  7. If supply present but no control change, backprobe connector and test continuity between BCM output and relay socket; check for shorts to battery or ground.
  8. If wiring and connectors are good and BCM output does not change, inspect BCM grounds and power. If BCM output is confirmed faulty, consider BCM repair/replacement and check for software updates.
  9. If intermittent, perform wiggle tests on harnesses while operating locks; repair broken wires or poor crimps with solder or proper connectors.
  10. After repair, clear codes and test multiple lock/unlock cycles; confirm no new B1300 or related codes appear.

Likely causes

  • Faulty relay or relay socket (most common)
  • Wiring/connectors to relay open or corroded
  • Blown fuse or poor supply to the relay
  • BCM driver fault (less common) or intermittent grounding
  • Aftermarket alarm or actuator causing short/overload

Fault status

⚠️ Status
Door electric locking relay coil circuit fault — open/short or relay/BCM drive issue detected.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2 hours

Similar codes

B1301 B1310 B1234 B1600 U0100
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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

B1300

MITSUBISHI B — Body

Topstack switch

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

Causes

  • Open or short in relay coil supply or return wiring
  • Corroded, loose or damaged relay connector or socket
  • Faulty door lock relay (coil open/short or intermittent)
  • Blown fuse or poor fuse connection in relay supply circuit
  • Poor ground or battery supply to relay/BCM
  • Body Control Module (BCM) output driver fault or software error

Symptoms

  • Central locking does not operate or operates intermittently
  • No audible relay click when locking/unlocking
  • Only some doors lock/unlock
  • Dashboard message or indicator about central locking error
  • Parasitic battery drain (rare) or fuse blowing
  • Remote key fob locking/unlocking ineffective or inconsistent

What to check

  • Read stored and pending codes with a diagnostic scanner; check BCM for related body/CAN errors
  • Visually inspect relay, relay socket, fuses and associated connectors for corrosion, heat damage or loose pins
  • Check fuse continuity and supply voltage to relay fuse
  • Listen for relay click while commanding locks from scanner or key fob
  • Measure voltage at relay coil supply and control pins during lock/unlock command
  • Measure coil resistance (relay removed) and compare with expected range

Signal parameters

  • Relay coil supply voltage (key ON): typically battery voltage ≈ 12 V
  • Control signal when activating: BCM usually grounds coil — control pin should go to ~0 V when active; inactive ≈ 12 V
  • Typical relay coil resistance: approx. 60–200 ohms (manufacturer-dependent) — expect coil current roughly 60–200 mA at 12 V
  • Activation duration: brief pulses during lock/unlock (usually < 2 seconds)
  • Fuse rating: check vehicle-specific manual (commonly 7.5 A–20 A for body circuits)

Diagnostic algorithm

  1. Confirm B1300 is current or stored; note freeze-frame and related codes from BCM.
  2. Visual inspection: check relay, socket, fuses and wiring for corrosion, damage or water ingress. Repair obvious issues.
  3. With key ON, command lock/unlock while listening for relay. If no click, proceed to electrical checks.
  4. Check fuse supplying the relay for continuity and battery voltage at both sides of the fuse.
  5. Remove relay and measure coil resistance across coil pins on the relay. If outside expected range, replace relay.
  6. With relay removed, measure supply voltage at the relay supply terminal (should be ~12 V) and monitor the control terminal while commanding locks. Control should switch to ~0 V (or change state) when activated.
  7. If supply present but no control change, backprobe connector and test continuity between BCM output and relay socket; check for shorts to battery or ground.
  8. If wiring and connectors are good and BCM output does not change, inspect BCM grounds and power. If BCM output is confirmed faulty, consider BCM repair/replacement and check for software updates.
  9. If intermittent, perform wiggle tests on harnesses while operating locks; repair broken wires or poor crimps with solder or proper connectors.
  10. After repair, clear codes and test multiple lock/unlock cycles; confirm no new B1300 or related codes appear.

Likely causes

  • Faulty relay or relay socket (most common)
  • Wiring/connectors to relay open or corroded
  • Blown fuse or poor supply to the relay
  • BCM driver fault (less common) or intermittent grounding
  • Aftermarket alarm or actuator causing short/overload

Fault status

⚠️ Status
Door electric locking relay coil circuit fault — open/short or relay/BCM drive issue detected.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2 hours

Similar codes

B1301 B1310 B1234 B1600 U0100
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

B1300

Other B — Body

Power Door Lock Circuit Failure

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

Causes

  • Open or short in relay coil supply or return wiring
  • Corroded, loose or damaged relay connector or socket
  • Faulty door lock relay (coil open/short or intermittent)
  • Blown fuse or poor fuse connection in relay supply circuit
  • Poor ground or battery supply to relay/BCM
  • Body Control Module (BCM) output driver fault or software error

Symptoms

  • Central locking does not operate or operates intermittently
  • No audible relay click when locking/unlocking
  • Only some doors lock/unlock
  • Dashboard message or indicator about central locking error
  • Parasitic battery drain (rare) or fuse blowing
  • Remote key fob locking/unlocking ineffective or inconsistent

What to check

  • Read stored and pending codes with a diagnostic scanner; check BCM for related body/CAN errors
  • Visually inspect relay, relay socket, fuses and associated connectors for corrosion, heat damage or loose pins
  • Check fuse continuity and supply voltage to relay fuse
  • Listen for relay click while commanding locks from scanner or key fob
  • Measure voltage at relay coil supply and control pins during lock/unlock command
  • Measure coil resistance (relay removed) and compare with expected range

Signal parameters

  • Relay coil supply voltage (key ON): typically battery voltage ≈ 12 V
  • Control signal when activating: BCM usually grounds coil — control pin should go to ~0 V when active; inactive ≈ 12 V
  • Typical relay coil resistance: approx. 60–200 ohms (manufacturer-dependent) — expect coil current roughly 60–200 mA at 12 V
  • Activation duration: brief pulses during lock/unlock (usually < 2 seconds)
  • Fuse rating: check vehicle-specific manual (commonly 7.5 A–20 A for body circuits)

Diagnostic algorithm

  1. Confirm B1300 is current or stored; note freeze-frame and related codes from BCM.
  2. Visual inspection: check relay, socket, fuses and wiring for corrosion, damage or water ingress. Repair obvious issues.
  3. With key ON, command lock/unlock while listening for relay. If no click, proceed to electrical checks.
  4. Check fuse supplying the relay for continuity and battery voltage at both sides of the fuse.
  5. Remove relay and measure coil resistance across coil pins on the relay. If outside expected range, replace relay.
  6. With relay removed, measure supply voltage at the relay supply terminal (should be ~12 V) and monitor the control terminal while commanding locks. Control should switch to ~0 V (or change state) when activated.
  7. If supply present but no control change, backprobe connector and test continuity between BCM output and relay socket; check for shorts to battery or ground.
  8. If wiring and connectors are good and BCM output does not change, inspect BCM grounds and power. If BCM output is confirmed faulty, consider BCM repair/replacement and check for software updates.
  9. If intermittent, perform wiggle tests on harnesses while operating locks; repair broken wires or poor crimps with solder or proper connectors.
  10. After repair, clear codes and test multiple lock/unlock cycles; confirm no new B1300 or related codes appear.

Likely causes

  • Faulty relay or relay socket (most common)
  • Wiring/connectors to relay open or corroded
  • Blown fuse or poor supply to the relay
  • BCM driver fault (less common) or intermittent grounding
  • Aftermarket alarm or actuator causing short/overload

Fault status

⚠️ Status
Door electric locking relay coil circuit fault — open/short or relay/BCM drive issue detected.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2 hours

Similar codes

B1301 B1310 B1234 B1600 U0100
9,352

The library contains 9,352 repair and diagnostic manuals. Choose a brand to open the full manual tree by year, model and trim.

ALFA ROMEO
89
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1,243
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479
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206
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456
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193
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75
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26
GENESIS
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138
HYUNDAI
371
ISUZU
86
KIA
78
LAND ROVER
320
LEXUS
280
LINCOLN
166
MERCEDES-BENZ
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MERCURY
296
MITSUBISHI
406
PORSCHE
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TESLA
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TRIUMPH
131
VOLKSWAGEN
626
VOLVO
221
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