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Home / DTC / B1401 — Front left full-open window relay short to ground

B1401 — Front left full-open window relay short to ground

Detailed page for trouble code B1401.

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22,491specific
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Code

B1401

ALFA ROMEO B — Body

Front left full-open window relay short to ground

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

Causes

  • Damaged or chafed wiring shorting the relay control circuit to chassis ground
  • Corroded, loose or damaged relay connector or terminals
  • Failed window full-open relay with internal short
  • Shorted output inside the body control module/comfort module
  • Water ingress in door harness or connector
  • Aftermarket equipment or recent repairs that disturbed wiring

Symptoms

  • Front-left window will not operate to full-open position or is inoperative
  • Blown related fuse or repeated fuse issues when commanding window
  • Relevant window switch or auto-down function does not work
  • Possible erratic operation or other window functions unaffected
  • B1401 stored in BCM or comfort module memory

What to check

  • Scan vehicle for stored codes and freeze-frame; note any other body or window codes
  • Visual inspection of door wiring harness, grommet at hinge, connector condition and signs of water ingress
  • Inspect relay socket and terminals for corrosion, melted plastic or burnt pins
  • Check related fuses and power supply to relay coil and motor circuits
  • With connector disconnected, measure continuity between the relay control pin and chassis ground
  • Backprobing the control output while commanding full-open to measure voltage and switching behavior

Signal parameters

  • With relay removed and module commanding: control output should switch between near 0 V (inactive) and approx. battery voltage (or module supply logic level) depending on design — consult wiring diagram for exact behavior
  • Relay coil resistance (bench) typically tens to a few hundred ohms for small relays; a near 0 ohm reading indicates short
  • Resistance from control pin to chassis ground with circuit disconnected should be high (kΩ to OL); a low ohm reading indicates a short to ground
  • Motor current when running (if relevant) will be several amps; abnormal current spikes or near-short currents indicate wiring fault

Diagnostic algorithm

  1. Record codes and clear then attempt to re-create the fault to confirm code returns.
  2. Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
  3. Disconnect the front-left window relay. With ignition on, command the full-open function while measuring the module’s relay-control pin voltage. Note whether the module is commanding and the observed voltage level.
  4. With ignition off, disconnect the relay connector from the harness and measure resistance from the relay control terminal to chassis ground. A low resistance indicates a short to ground in the harness or module.
  5. Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
  6. If the harness shows a short with connector disconnected, unplug the door-side connectors and repeat resistance checks to localize the short (door side vs. body harness).
  7. Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
  8. If wiring appears intact and the short remains on the body side, consult the wiring diagram and test continuity from the module output pin to the relay connector. If short persists at module output, suspect module internal fault.
  9. Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
  10. If module replacement is required, follow OEM procedures for programming and coding; confirm repair by rechecking the circuit and clearing codes.

Likely causes

  • Wiring abrasion where harness passes through door hinge or inside door (most common)
  • Corroded/contaminated relay connector pins
  • Failed relay coil or contacts causing internal short
  • Module output transistor failure (less common)

Fault status

⚠️ Status
Front-left full-open window relay control circuit shorted to ground detected by body control module; this may disable the auto full-open window function until wiring or module is repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1400 B1402 B1403 B1404 B1405
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

B1401

FIAT B — Body

Front left full-open window relay short to ground

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

Causes

  • Damaged or chafed wiring shorting the relay control circuit to chassis ground
  • Corroded, loose or damaged relay connector or terminals
  • Failed window full-open relay with internal short
  • Shorted output inside the body control module/comfort module
  • Water ingress in door harness or connector
  • Aftermarket equipment or recent repairs that disturbed wiring

Symptoms

  • Front-left window will not operate to full-open position or is inoperative
  • Blown related fuse or repeated fuse issues when commanding window
  • Relevant window switch or auto-down function does not work
  • Possible erratic operation or other window functions unaffected
  • B1401 stored in BCM or comfort module memory

What to check

  • Scan vehicle for stored codes and freeze-frame; note any other body or window codes
  • Visual inspection of door wiring harness, grommet at hinge, connector condition and signs of water ingress
  • Inspect relay socket and terminals for corrosion, melted plastic or burnt pins
  • Check related fuses and power supply to relay coil and motor circuits
  • With connector disconnected, measure continuity between the relay control pin and chassis ground
  • Backprobing the control output while commanding full-open to measure voltage and switching behavior

Signal parameters

  • With relay removed and module commanding: control output should switch between near 0 V (inactive) and approx. battery voltage (or module supply logic level) depending on design — consult wiring diagram for exact behavior
  • Relay coil resistance (bench) typically tens to a few hundred ohms for small relays; a near 0 ohm reading indicates short
  • Resistance from control pin to chassis ground with circuit disconnected should be high (kΩ to OL); a low ohm reading indicates a short to ground
  • Motor current when running (if relevant) will be several amps; abnormal current spikes or near-short currents indicate wiring fault

Diagnostic algorithm

  1. Record codes and clear then attempt to re-create the fault to confirm code returns.
  2. Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
  3. Disconnect the front-left window relay. With ignition on, command the full-open function while measuring the module’s relay-control pin voltage. Note whether the module is commanding and the observed voltage level.
  4. With ignition off, disconnect the relay connector from the harness and measure resistance from the relay control terminal to chassis ground. A low resistance indicates a short to ground in the harness or module.
  5. Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
  6. If the harness shows a short with connector disconnected, unplug the door-side connectors and repeat resistance checks to localize the short (door side vs. body harness).
  7. Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
  8. If wiring appears intact and the short remains on the body side, consult the wiring diagram and test continuity from the module output pin to the relay connector. If short persists at module output, suspect module internal fault.
  9. Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
  10. If module replacement is required, follow OEM procedures for programming and coding; confirm repair by rechecking the circuit and clearing codes.

Likely causes

  • Wiring abrasion where harness passes through door hinge or inside door (most common)
  • Corroded/contaminated relay connector pins
  • Failed relay coil or contacts causing internal short
  • Module output transistor failure (less common)

Fault status

⚠️ Status
Front-left full-open window relay control circuit shorted to ground detected by body control module; this may disable the auto full-open window function until wiring or module is repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1400 B1402 B1403 B1404 B1405
Repair manuals

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

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Code

B1401

LAND ROVER B — Body

Request for parking assistance output

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

Causes

  • Damaged or chafed wiring shorting the relay control circuit to chassis ground
  • Corroded, loose or damaged relay connector or terminals
  • Failed window full-open relay with internal short
  • Shorted output inside the body control module/comfort module
  • Water ingress in door harness or connector
  • Aftermarket equipment or recent repairs that disturbed wiring

Symptoms

  • Front-left window will not operate to full-open position or is inoperative
  • Blown related fuse or repeated fuse issues when commanding window
  • Relevant window switch or auto-down function does not work
  • Possible erratic operation or other window functions unaffected
  • B1401 stored in BCM or comfort module memory

What to check

  • Scan vehicle for stored codes and freeze-frame; note any other body or window codes
  • Visual inspection of door wiring harness, grommet at hinge, connector condition and signs of water ingress
  • Inspect relay socket and terminals for corrosion, melted plastic or burnt pins
  • Check related fuses and power supply to relay coil and motor circuits
  • With connector disconnected, measure continuity between the relay control pin and chassis ground
  • Backprobing the control output while commanding full-open to measure voltage and switching behavior

Signal parameters

  • With relay removed and module commanding: control output should switch between near 0 V (inactive) and approx. battery voltage (or module supply logic level) depending on design — consult wiring diagram for exact behavior
  • Relay coil resistance (bench) typically tens to a few hundred ohms for small relays; a near 0 ohm reading indicates short
  • Resistance from control pin to chassis ground with circuit disconnected should be high (kΩ to OL); a low ohm reading indicates a short to ground
  • Motor current when running (if relevant) will be several amps; abnormal current spikes or near-short currents indicate wiring fault

Diagnostic algorithm

  1. Record codes and clear then attempt to re-create the fault to confirm code returns.
  2. Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
  3. Disconnect the front-left window relay. With ignition on, command the full-open function while measuring the module’s relay-control pin voltage. Note whether the module is commanding and the observed voltage level.
  4. With ignition off, disconnect the relay connector from the harness and measure resistance from the relay control terminal to chassis ground. A low resistance indicates a short to ground in the harness or module.
  5. Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
  6. If the harness shows a short with connector disconnected, unplug the door-side connectors and repeat resistance checks to localize the short (door side vs. body harness).
  7. Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
  8. If wiring appears intact and the short remains on the body side, consult the wiring diagram and test continuity from the module output pin to the relay connector. If short persists at module output, suspect module internal fault.
  9. Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
  10. If module replacement is required, follow OEM procedures for programming and coding; confirm repair by rechecking the circuit and clearing codes.

Likely causes

  • Wiring abrasion where harness passes through door hinge or inside door (most common)
  • Corroded/contaminated relay connector pins
  • Failed relay coil or contacts causing internal short
  • Module output transistor failure (less common)

Fault status

⚠️ Status
Front-left full-open window relay control circuit shorted to ground detected by body control module; this may disable the auto full-open window function until wiring or module is repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1400 B1402 B1403 B1404 B1405
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.
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Code

B1401

MITSUBISHI B — Body

F ABG(1)DR.squib open

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

Causes

  • Damaged or chafed wiring shorting the relay control circuit to chassis ground
  • Corroded, loose or damaged relay connector or terminals
  • Failed window full-open relay with internal short
  • Shorted output inside the body control module/comfort module
  • Water ingress in door harness or connector
  • Aftermarket equipment or recent repairs that disturbed wiring

Symptoms

  • Front-left window will not operate to full-open position or is inoperative
  • Blown related fuse or repeated fuse issues when commanding window
  • Relevant window switch or auto-down function does not work
  • Possible erratic operation or other window functions unaffected
  • B1401 stored in BCM or comfort module memory

What to check

  • Scan vehicle for stored codes and freeze-frame; note any other body or window codes
  • Visual inspection of door wiring harness, grommet at hinge, connector condition and signs of water ingress
  • Inspect relay socket and terminals for corrosion, melted plastic or burnt pins
  • Check related fuses and power supply to relay coil and motor circuits
  • With connector disconnected, measure continuity between the relay control pin and chassis ground
  • Backprobing the control output while commanding full-open to measure voltage and switching behavior

Signal parameters

  • With relay removed and module commanding: control output should switch between near 0 V (inactive) and approx. battery voltage (or module supply logic level) depending on design — consult wiring diagram for exact behavior
  • Relay coil resistance (bench) typically tens to a few hundred ohms for small relays; a near 0 ohm reading indicates short
  • Resistance from control pin to chassis ground with circuit disconnected should be high (kΩ to OL); a low ohm reading indicates a short to ground
  • Motor current when running (if relevant) will be several amps; abnormal current spikes or near-short currents indicate wiring fault

Diagnostic algorithm

  1. Record codes and clear then attempt to re-create the fault to confirm code returns.
  2. Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
  3. Disconnect the front-left window relay. With ignition on, command the full-open function while measuring the module’s relay-control pin voltage. Note whether the module is commanding and the observed voltage level.
  4. With ignition off, disconnect the relay connector from the harness and measure resistance from the relay control terminal to chassis ground. A low resistance indicates a short to ground in the harness or module.
  5. Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
  6. If the harness shows a short with connector disconnected, unplug the door-side connectors and repeat resistance checks to localize the short (door side vs. body harness).
  7. Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
  8. If wiring appears intact and the short remains on the body side, consult the wiring diagram and test continuity from the module output pin to the relay connector. If short persists at module output, suspect module internal fault.
  9. Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
  10. If module replacement is required, follow OEM procedures for programming and coding; confirm repair by rechecking the circuit and clearing codes.

Likely causes

  • Wiring abrasion where harness passes through door hinge or inside door (most common)
  • Corroded/contaminated relay connector pins
  • Failed relay coil or contacts causing internal short
  • Module output transistor failure (less common)

Fault status

⚠️ Status
Front-left full-open window relay control circuit shorted to ground detected by body control module; this may disable the auto full-open window function until wiring or module is repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1400 B1402 B1403 B1404 B1405
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

B1401

Other B — Body

Driver Power Window One Touch Window Relay Circuit Short To Ground

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

Causes

  • Damaged or chafed wiring shorting the relay control circuit to chassis ground
  • Corroded, loose or damaged relay connector or terminals
  • Failed window full-open relay with internal short
  • Shorted output inside the body control module/comfort module
  • Water ingress in door harness or connector
  • Aftermarket equipment or recent repairs that disturbed wiring

Symptoms

  • Front-left window will not operate to full-open position or is inoperative
  • Blown related fuse or repeated fuse issues when commanding window
  • Relevant window switch or auto-down function does not work
  • Possible erratic operation or other window functions unaffected
  • B1401 stored in BCM or comfort module memory

What to check

  • Scan vehicle for stored codes and freeze-frame; note any other body or window codes
  • Visual inspection of door wiring harness, grommet at hinge, connector condition and signs of water ingress
  • Inspect relay socket and terminals for corrosion, melted plastic or burnt pins
  • Check related fuses and power supply to relay coil and motor circuits
  • With connector disconnected, measure continuity between the relay control pin and chassis ground
  • Backprobing the control output while commanding full-open to measure voltage and switching behavior

Signal parameters

  • With relay removed and module commanding: control output should switch between near 0 V (inactive) and approx. battery voltage (or module supply logic level) depending on design — consult wiring diagram for exact behavior
  • Relay coil resistance (bench) typically tens to a few hundred ohms for small relays; a near 0 ohm reading indicates short
  • Resistance from control pin to chassis ground with circuit disconnected should be high (kΩ to OL); a low ohm reading indicates a short to ground
  • Motor current when running (if relevant) will be several amps; abnormal current spikes or near-short currents indicate wiring fault

Diagnostic algorithm

  1. Record codes and clear then attempt to re-create the fault to confirm code returns.
  2. Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
  3. Disconnect the front-left window relay. With ignition on, command the full-open function while measuring the module’s relay-control pin voltage. Note whether the module is commanding and the observed voltage level.
  4. With ignition off, disconnect the relay connector from the harness and measure resistance from the relay control terminal to chassis ground. A low resistance indicates a short to ground in the harness or module.
  5. Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
  6. If the harness shows a short with connector disconnected, unplug the door-side connectors and repeat resistance checks to localize the short (door side vs. body harness).
  7. Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
  8. If wiring appears intact and the short remains on the body side, consult the wiring diagram and test continuity from the module output pin to the relay connector. If short persists at module output, suspect module internal fault.
  9. Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
  10. If module replacement is required, follow OEM procedures for programming and coding; confirm repair by rechecking the circuit and clearing codes.

Likely causes

  • Wiring abrasion where harness passes through door hinge or inside door (most common)
  • Corroded/contaminated relay connector pins
  • Failed relay coil or contacts causing internal short
  • Module output transistor failure (less common)

Fault status

⚠️ Status
Front-left full-open window relay control circuit shorted to ground detected by body control module; this may disable the auto full-open window function until wiring or module is repaired.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1400 B1402 B1403 B1404 B1405
9,387

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