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Home / DTC / B1522 — Bonnet switch circuit

B1522 — Bonnet switch circuit

Detailed page for trouble code B1522.

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Code

B1522

ALFA ROMEO B — Body

Bonnet switch circuit

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

Causes

  • Open or short in bonnet switch wiring
  • Corroded or damaged bonnet (hood) switch
  • Poor connector contacts or water ingress at switch or module connector
  • Faulty body control module (BCM) or instrument cluster input
  • Intermittent mechanical switch contact (sticking)
  • Blown fuse or poor ground related to the bonnet circuit

Symptoms

  • Bonnet/hood open warning lamp or message on dash
  • Alarm or immobilizer may not arm/disarm correctly
  • Interior courtesy lights may stay on or not come on as expected
  • Central locking or security system behaves intermittently
  • DTC stored and possibly multiple attempts to set/clear the message

What to check

  • Read stored DTCs and freeze frame data with a diagnostic scanner; note related codes
  • Visually inspect bonnet switch, wiring along hinge, and connectors for damage or corrosion
  • Wiggle harness while watching live data to reproduce intermittent faults
  • Backprobe the switch connector and check voltage/ground with bonnet open/closed
  • Check continuity and resistance of switch with multimeter (switch open = high/infinite, closed = near 0 Ω)
  • Check power and ground fuses and module grounds related to body control module

Signal parameters

  • Typical switch behavior: open-circuit when bonnet closed, closed to ground when bonnet open (or vice versa depending on vehicle)
  • Idle voltage at signal line with switch open: near battery voltage (approx. 12 V) or pull-up voltage specified by module
  • Voltage at signal line with switch closed: near 0 V (ground) or low logic level
  • Closed-switch resistance: ≈ 0–5 Ω (near short to ground)
  • Open-switch resistance: very high / infinite

Diagnostic algorithm

  1. Confirm the B1522 code and any related codes with a diagnostic scanner. Record freeze frame/live data for bonnet switch input.
  2. Visually inspect bonnet switch, striker area, wiring along the hinge, and both connectors for damage, dirt, corrosion, or signs of water ingress.
  3. With connector disconnected, measure resistance across the switch while operating the bonnet latch: closed = open circuit (high Ω) or closed = low Ω depending on switch design; compare to expected behavior.
  4. Reconnect and backprobe the signal wire. Observe voltage with bonnet closed and open. Expect a clear change (e.g., ~12 V ↔ ~0 V). If no change, move to wiring checks.
  5. Check continuity between the switch signal pin and the BCM/input pin. Repair any open circuits or chafing found, especially at hinge points.
  6. Check for shorts to battery or ground by measuring resistance from the signal wire to battery + and to chassis ground with connector disconnected.
  7. Clean or replace corroded connectors. If wiring and switch test OK but signal remains incorrect, check BCM power/ground and inputs. Swap or test BCM input if procedures available.
  8. After repairs, clear codes and perform functional test by opening/closing bonnet and verifying the input changes in live data and that the DTC does not return.
  9. If intermittent: monitor with scanner over time or perform wiggle test to replicate intermittent failure; secure or replace wiring as required.

Likely causes

  • Broken or chafed harness where it flexes at the bonnet hinge
  • Corrosion inside the bonnet switch assembly (common in wet climates)
  • Connector pin pushed out, bent, or contaminated at the switch or BCM
  • Short to battery or chassis ground caused by damaged insulation
  • Internal failure of the bonnet switch contacts

Fault status

⚠️ Status
Bonnet switch circuit fault — abnormal/open/short/intermittent signal detected by body control module. May affect bonnet open warning, alarm and interior lighting functions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1520 B1521 B1523 B1600 B2799
89

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

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Code

B1522

FIAT B — Body

Bonnet switch circuit

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

Causes

  • Open or short in bonnet switch wiring
  • Corroded or damaged bonnet (hood) switch
  • Poor connector contacts or water ingress at switch or module connector
  • Faulty body control module (BCM) or instrument cluster input
  • Intermittent mechanical switch contact (sticking)
  • Blown fuse or poor ground related to the bonnet circuit

Symptoms

  • Bonnet/hood open warning lamp or message on dash
  • Alarm or immobilizer may not arm/disarm correctly
  • Interior courtesy lights may stay on or not come on as expected
  • Central locking or security system behaves intermittently
  • DTC stored and possibly multiple attempts to set/clear the message

What to check

  • Read stored DTCs and freeze frame data with a diagnostic scanner; note related codes
  • Visually inspect bonnet switch, wiring along hinge, and connectors for damage or corrosion
  • Wiggle harness while watching live data to reproduce intermittent faults
  • Backprobe the switch connector and check voltage/ground with bonnet open/closed
  • Check continuity and resistance of switch with multimeter (switch open = high/infinite, closed = near 0 Ω)
  • Check power and ground fuses and module grounds related to body control module

Signal parameters

  • Typical switch behavior: open-circuit when bonnet closed, closed to ground when bonnet open (or vice versa depending on vehicle)
  • Idle voltage at signal line with switch open: near battery voltage (approx. 12 V) or pull-up voltage specified by module
  • Voltage at signal line with switch closed: near 0 V (ground) or low logic level
  • Closed-switch resistance: ≈ 0–5 Ω (near short to ground)
  • Open-switch resistance: very high / infinite

Diagnostic algorithm

  1. Confirm the B1522 code and any related codes with a diagnostic scanner. Record freeze frame/live data for bonnet switch input.
  2. Visually inspect bonnet switch, striker area, wiring along the hinge, and both connectors for damage, dirt, corrosion, or signs of water ingress.
  3. With connector disconnected, measure resistance across the switch while operating the bonnet latch: closed = open circuit (high Ω) or closed = low Ω depending on switch design; compare to expected behavior.
  4. Reconnect and backprobe the signal wire. Observe voltage with bonnet closed and open. Expect a clear change (e.g., ~12 V ↔ ~0 V). If no change, move to wiring checks.
  5. Check continuity between the switch signal pin and the BCM/input pin. Repair any open circuits or chafing found, especially at hinge points.
  6. Check for shorts to battery or ground by measuring resistance from the signal wire to battery + and to chassis ground with connector disconnected.
  7. Clean or replace corroded connectors. If wiring and switch test OK but signal remains incorrect, check BCM power/ground and inputs. Swap or test BCM input if procedures available.
  8. After repairs, clear codes and perform functional test by opening/closing bonnet and verifying the input changes in live data and that the DTC does not return.
  9. If intermittent: monitor with scanner over time or perform wiggle test to replicate intermittent failure; secure or replace wiring as required.

Likely causes

  • Broken or chafed harness where it flexes at the bonnet hinge
  • Corrosion inside the bonnet switch assembly (common in wet climates)
  • Connector pin pushed out, bent, or contaminated at the switch or BCM
  • Short to battery or chassis ground caused by damaged insulation
  • Internal failure of the bonnet switch contacts

Fault status

⚠️ Status
Bonnet switch circuit fault — abnormal/open/short/intermittent signal detected by body control module. May affect bonnet open warning, alarm and interior lighting functions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1520 B1521 B1523 B1600 B2799
Repair manuals

Manual library for FIAT

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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

B1522

MITSUBISHI B — Body

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

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

Causes

  • Open or short in bonnet switch wiring
  • Corroded or damaged bonnet (hood) switch
  • Poor connector contacts or water ingress at switch or module connector
  • Faulty body control module (BCM) or instrument cluster input
  • Intermittent mechanical switch contact (sticking)
  • Blown fuse or poor ground related to the bonnet circuit

Symptoms

  • Bonnet/hood open warning lamp or message on dash
  • Alarm or immobilizer may not arm/disarm correctly
  • Interior courtesy lights may stay on or not come on as expected
  • Central locking or security system behaves intermittently
  • DTC stored and possibly multiple attempts to set/clear the message

What to check

  • Read stored DTCs and freeze frame data with a diagnostic scanner; note related codes
  • Visually inspect bonnet switch, wiring along hinge, and connectors for damage or corrosion
  • Wiggle harness while watching live data to reproduce intermittent faults
  • Backprobe the switch connector and check voltage/ground with bonnet open/closed
  • Check continuity and resistance of switch with multimeter (switch open = high/infinite, closed = near 0 Ω)
  • Check power and ground fuses and module grounds related to body control module

Signal parameters

  • Typical switch behavior: open-circuit when bonnet closed, closed to ground when bonnet open (or vice versa depending on vehicle)
  • Idle voltage at signal line with switch open: near battery voltage (approx. 12 V) or pull-up voltage specified by module
  • Voltage at signal line with switch closed: near 0 V (ground) or low logic level
  • Closed-switch resistance: ≈ 0–5 Ω (near short to ground)
  • Open-switch resistance: very high / infinite

Diagnostic algorithm

  1. Confirm the B1522 code and any related codes with a diagnostic scanner. Record freeze frame/live data for bonnet switch input.
  2. Visually inspect bonnet switch, striker area, wiring along the hinge, and both connectors for damage, dirt, corrosion, or signs of water ingress.
  3. With connector disconnected, measure resistance across the switch while operating the bonnet latch: closed = open circuit (high Ω) or closed = low Ω depending on switch design; compare to expected behavior.
  4. Reconnect and backprobe the signal wire. Observe voltage with bonnet closed and open. Expect a clear change (e.g., ~12 V ↔ ~0 V). If no change, move to wiring checks.
  5. Check continuity between the switch signal pin and the BCM/input pin. Repair any open circuits or chafing found, especially at hinge points.
  6. Check for shorts to battery or ground by measuring resistance from the signal wire to battery + and to chassis ground with connector disconnected.
  7. Clean or replace corroded connectors. If wiring and switch test OK but signal remains incorrect, check BCM power/ground and inputs. Swap or test BCM input if procedures available.
  8. After repairs, clear codes and perform functional test by opening/closing bonnet and verifying the input changes in live data and that the DTC does not return.
  9. If intermittent: monitor with scanner over time or perform wiggle test to replicate intermittent failure; secure or replace wiring as required.

Likely causes

  • Broken or chafed harness where it flexes at the bonnet hinge
  • Corrosion inside the bonnet switch assembly (common in wet climates)
  • Connector pin pushed out, bent, or contaminated at the switch or BCM
  • Short to battery or chassis ground caused by damaged insulation
  • Internal failure of the bonnet switch contacts

Fault status

⚠️ Status
Bonnet switch circuit fault — abnormal/open/short/intermittent signal detected by body control module. May affect bonnet open warning, alarm and interior lighting functions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1520 B1521 B1523 B1600 B2799
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

B1522

Other B — Body

Hood Switch Circuit Short To Ground

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

Causes

  • Open or short in bonnet switch wiring
  • Corroded or damaged bonnet (hood) switch
  • Poor connector contacts or water ingress at switch or module connector
  • Faulty body control module (BCM) or instrument cluster input
  • Intermittent mechanical switch contact (sticking)
  • Blown fuse or poor ground related to the bonnet circuit

Symptoms

  • Bonnet/hood open warning lamp or message on dash
  • Alarm or immobilizer may not arm/disarm correctly
  • Interior courtesy lights may stay on or not come on as expected
  • Central locking or security system behaves intermittently
  • DTC stored and possibly multiple attempts to set/clear the message

What to check

  • Read stored DTCs and freeze frame data with a diagnostic scanner; note related codes
  • Visually inspect bonnet switch, wiring along hinge, and connectors for damage or corrosion
  • Wiggle harness while watching live data to reproduce intermittent faults
  • Backprobe the switch connector and check voltage/ground with bonnet open/closed
  • Check continuity and resistance of switch with multimeter (switch open = high/infinite, closed = near 0 Ω)
  • Check power and ground fuses and module grounds related to body control module

Signal parameters

  • Typical switch behavior: open-circuit when bonnet closed, closed to ground when bonnet open (or vice versa depending on vehicle)
  • Idle voltage at signal line with switch open: near battery voltage (approx. 12 V) or pull-up voltage specified by module
  • Voltage at signal line with switch closed: near 0 V (ground) or low logic level
  • Closed-switch resistance: ≈ 0–5 Ω (near short to ground)
  • Open-switch resistance: very high / infinite

Diagnostic algorithm

  1. Confirm the B1522 code and any related codes with a diagnostic scanner. Record freeze frame/live data for bonnet switch input.
  2. Visually inspect bonnet switch, striker area, wiring along the hinge, and both connectors for damage, dirt, corrosion, or signs of water ingress.
  3. With connector disconnected, measure resistance across the switch while operating the bonnet latch: closed = open circuit (high Ω) or closed = low Ω depending on switch design; compare to expected behavior.
  4. Reconnect and backprobe the signal wire. Observe voltage with bonnet closed and open. Expect a clear change (e.g., ~12 V ↔ ~0 V). If no change, move to wiring checks.
  5. Check continuity between the switch signal pin and the BCM/input pin. Repair any open circuits or chafing found, especially at hinge points.
  6. Check for shorts to battery or ground by measuring resistance from the signal wire to battery + and to chassis ground with connector disconnected.
  7. Clean or replace corroded connectors. If wiring and switch test OK but signal remains incorrect, check BCM power/ground and inputs. Swap or test BCM input if procedures available.
  8. After repairs, clear codes and perform functional test by opening/closing bonnet and verifying the input changes in live data and that the DTC does not return.
  9. If intermittent: monitor with scanner over time or perform wiggle test to replicate intermittent failure; secure or replace wiring as required.

Likely causes

  • Broken or chafed harness where it flexes at the bonnet hinge
  • Corrosion inside the bonnet switch assembly (common in wet climates)
  • Connector pin pushed out, bent, or contaminated at the switch or BCM
  • Short to battery or chassis ground caused by damaged insulation
  • Internal failure of the bonnet switch contacts

Fault status

⚠️ Status
Bonnet switch circuit fault — abnormal/open/short/intermittent signal detected by body control module. May affect bonnet open warning, alarm and interior lighting functions.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1520 B1521 B1523 B1600 B2799
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