Code
B1401
ALFA ROMEO
B — Body
Front left full-open window relay short to ground
Views:
UK: 11
EN: 8
RU: 17
AI status
Completed
Completed
100%
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
- Record codes and clear then attempt to re-create the fault to confirm code returns.
- Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
- 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.
- 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.
- Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
- 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).
- Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
- 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.
- Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
- 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
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Code
B1401
FIAT
B — Body
Front left full-open window relay short to ground
Views:
UK: 11
EN: 8
RU: 17
AI status
Completed
Completed
100%
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
- Record codes and clear then attempt to re-create the fault to confirm code returns.
- Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
- 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.
- 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.
- Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
- 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).
- Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
- 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.
- Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
- 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
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Code
B1401
LAND ROVER
B — Body
Request for parking assistance output
Views:
UK: 15
EN: 10
RU: 28
AI status
Completed
Completed
100%
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
- Record codes and clear then attempt to re-create the fault to confirm code returns.
- Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
- 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.
- 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.
- Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
- 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).
- Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
- 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.
- Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
- 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
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Code
B1401
MITSUBISHI
B — Body
F ABG(1)DR.squib open
Views:
UK: 18
EN: 15
RU: 31
AI status
Completed
Completed
100%
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
- Record codes and clear then attempt to re-create the fault to confirm code returns.
- Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
- 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.
- 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.
- Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
- 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).
- Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
- 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.
- Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
- 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
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+100 karma for a short comment :)
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Send to email
Code
B1401
Other
B — Body
Driver Power Window One Touch Window Relay Circuit Short To Ground
Views:
UK: 30
EN: 21
RU: 41
AI status
Completed
Completed
100%
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
- Record codes and clear then attempt to re-create the fault to confirm code returns.
- Perform a visual inspection of the front-left door wiring, hinge grommet and connectors for damage, pin corrosion, or water entry.
- 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.
- 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.
- Bench-test or swap the relay with a known-good relay of the same type to exclude a failed relay.
- 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).
- Perform a wiggle test while commanding the function to check for intermittent shorts where the harness flexes at the hinge.
- 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.
- Repair or replace damaged wiring, connectors or relay as found. After repair, clear codes and verify proper operation and that code does not return.
- 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
Your experience will help others
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Was this AI description helpful?
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