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Home / DTC / B1484 — Brake pedal input signal open circuit between brake switch and stop lamps

B1484 — Brake pedal input signal open circuit between brake switch and stop lamps

Detailed page for trouble code B1484.

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Code

B1484

ALFA ROMEO B — Body

Brake pedal input signal open circuit between brake switch and stop lamps

Brand: ALFA ROMEO
Type: B — Body
Views: UK: 18 EN: 94 RU: 23
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or broken wiring between brake switch and stop lamps
  • Faulty brake light (stop lamp) switch
  • Blown fuse or fusible link for brake/stop lamps
  • Burnt-out or disconnected stop lamp bulb(s) or LED module failure
  • Corroded/damaged connectors (at switch, lamps or body control module)
  • Poor ground at lamp(s) or body control module

Symptoms

  • Brake lights do not illuminate when brake pedal is pressed or are intermittent
  • Brake lights stay off for one or more lamps (center or outer)
  • Dash may show brake/ABS warning or related message
  • Cruise control or shift interlock may be disabled on some models
  • DTC stored and possible reduced functionality of driver assistance systems that read brake input

What to check

  • Use scan tool to confirm B1484 stored and note freeze frame data
  • Visually inspect rear stop lamps (bulbs/LED lenses) and connectors for damage or corrosion
  • Check fuses and fusible links related to brake/stop lamp circuit
  • Operate brake pedal and confirm which lamps illuminate (left/right/center)
  • Back-probe brake light switch connector and lamp socket(s) to measure voltage with pedal pressed/released
  • Perform continuity/ohm check between brake switch output terminal and each stop lamp positive terminal with battery disconnected

Signal parameters

  • Supply voltage at brake light switch (with ignition on): ~11–14 V (battery voltage)
  • At lamp positive terminal when pedal released: ~0 V; when pedal pressed: ~11–14 V (depending on circuit design)
  • Continuity (ohms) from brake switch output to lamp positive: low ohms; open circuit indicated by OL/infinite
  • Typical stop lamp filament resistance (incandescent): a few ohms to tens of ohms; LEDs will show different characteristics—check as assemblies; current draw when lamp ON: incandescent lamps = several hundred mA per filament; LEDs much lower

Diagnostic algorithm

  1. Read and record freeze frame and any related DTCs with a scan tool; do not clear codes yet
  2. Visually inspect rear lamp assemblies, connectors and ground points for corrosion, damage or disconnection; replace/clean as needed
  3. Check relevant fuses and replace if blown; if fuse blows repeatedly, suspect short to ground downstream
  4. Confirm operation: have an assistant press the brake pedal while you observe each stop lamp; note which lamps fail to illuminate
  5. Back-probe brake light switch connector: measure voltage on switch input and output with ignition on. Expected: battery voltage to switch input; output should be 0 V (or ground depending on design) with pedal released and battery voltage with pedal pressed
  6. If no voltage at switch output when pressed, remove switch and bench-test for continuity/resistance or replace if faulty
  7. If switch output is correct, measure voltage at lamp socket(s) while pedal is pressed. If no voltage at socket, perform continuity test between switch output terminal and lamp positive terminal with battery disconnected
  8. Inspect and test ground at lamp negative terminal; a bad ground can mimic open-circuit symptoms
  9. If continuity/open-circuit is found in wiring, trace wiring harness to locate damage; repair with proper splices, heat-shrink, and corrosion protection
  10. If wiring and switch test good but fault remains, inspect connectors at BCM/body module and check for BCM input pin continuity and voltage. Consider BCM replacement only after eliminating wiring and component failures
  11. After repairs, clear codes, cycle ignition and perform functional test with brake pedal; confirm no return of B1484 and proper lamp operation

Likely causes

  • Wiring damage (chaffed, pinched or broken conductor) between switch and rear lamps
  • Failed brake light switch or misadjusted switch plunger
  • Blown fuse or failed bulb filament/LED module causing open circuit
  • Corroded connector at rear lamp or at brake switch causing intermittent/open contact

Fault status

⚠️ Status
Open circuit detected between brake switch and stop lamp circuit — brake pedal input signal not reaching stop lamps.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1480 B1482 B1485 U0121 U0123
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Code

B1484

FIAT B — Body

Brake pedal input signal open circuit between brake switch and stop lamps

Brand: FIAT
Type: B — Body
Views: UK: 16 EN: 97 RU: 20
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or broken wiring between brake switch and stop lamps
  • Faulty brake light (stop lamp) switch
  • Blown fuse or fusible link for brake/stop lamps
  • Burnt-out or disconnected stop lamp bulb(s) or LED module failure
  • Corroded/damaged connectors (at switch, lamps or body control module)
  • Poor ground at lamp(s) or body control module

Symptoms

  • Brake lights do not illuminate when brake pedal is pressed or are intermittent
  • Brake lights stay off for one or more lamps (center or outer)
  • Dash may show brake/ABS warning or related message
  • Cruise control or shift interlock may be disabled on some models
  • DTC stored and possible reduced functionality of driver assistance systems that read brake input

What to check

  • Use scan tool to confirm B1484 stored and note freeze frame data
  • Visually inspect rear stop lamps (bulbs/LED lenses) and connectors for damage or corrosion
  • Check fuses and fusible links related to brake/stop lamp circuit
  • Operate brake pedal and confirm which lamps illuminate (left/right/center)
  • Back-probe brake light switch connector and lamp socket(s) to measure voltage with pedal pressed/released
  • Perform continuity/ohm check between brake switch output terminal and each stop lamp positive terminal with battery disconnected

Signal parameters

  • Supply voltage at brake light switch (with ignition on): ~11–14 V (battery voltage)
  • At lamp positive terminal when pedal released: ~0 V; when pedal pressed: ~11–14 V (depending on circuit design)
  • Continuity (ohms) from brake switch output to lamp positive: low ohms; open circuit indicated by OL/infinite
  • Typical stop lamp filament resistance (incandescent): a few ohms to tens of ohms; LEDs will show different characteristics—check as assemblies; current draw when lamp ON: incandescent lamps = several hundred mA per filament; LEDs much lower

Diagnostic algorithm

  1. Read and record freeze frame and any related DTCs with a scan tool; do not clear codes yet
  2. Visually inspect rear lamp assemblies, connectors and ground points for corrosion, damage or disconnection; replace/clean as needed
  3. Check relevant fuses and replace if blown; if fuse blows repeatedly, suspect short to ground downstream
  4. Confirm operation: have an assistant press the brake pedal while you observe each stop lamp; note which lamps fail to illuminate
  5. Back-probe brake light switch connector: measure voltage on switch input and output with ignition on. Expected: battery voltage to switch input; output should be 0 V (or ground depending on design) with pedal released and battery voltage with pedal pressed
  6. If no voltage at switch output when pressed, remove switch and bench-test for continuity/resistance or replace if faulty
  7. If switch output is correct, measure voltage at lamp socket(s) while pedal is pressed. If no voltage at socket, perform continuity test between switch output terminal and lamp positive terminal with battery disconnected
  8. Inspect and test ground at lamp negative terminal; a bad ground can mimic open-circuit symptoms
  9. If continuity/open-circuit is found in wiring, trace wiring harness to locate damage; repair with proper splices, heat-shrink, and corrosion protection
  10. If wiring and switch test good but fault remains, inspect connectors at BCM/body module and check for BCM input pin continuity and voltage. Consider BCM replacement only after eliminating wiring and component failures
  11. After repairs, clear codes, cycle ignition and perform functional test with brake pedal; confirm no return of B1484 and proper lamp operation

Likely causes

  • Wiring damage (chaffed, pinched or broken conductor) between switch and rear lamps
  • Failed brake light switch or misadjusted switch plunger
  • Blown fuse or failed bulb filament/LED module causing open circuit
  • Corroded connector at rear lamp or at brake switch causing intermittent/open contact

Fault status

⚠️ Status
Open circuit detected between brake switch and stop lamp circuit — brake pedal input signal not reaching stop lamps.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1480 B1482 B1485 U0121 U0123
Repair manuals

Manual library for FIAT

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Code

B1484

MITSUBISHI B — Body

F ABG(2)DR active circuit short

Brand: MITSUBISHI
Type: B — Body
Views: UK: 20 EN: 101 RU: 23
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or broken wiring between brake switch and stop lamps
  • Faulty brake light (stop lamp) switch
  • Blown fuse or fusible link for brake/stop lamps
  • Burnt-out or disconnected stop lamp bulb(s) or LED module failure
  • Corroded/damaged connectors (at switch, lamps or body control module)
  • Poor ground at lamp(s) or body control module

Symptoms

  • Brake lights do not illuminate when brake pedal is pressed or are intermittent
  • Brake lights stay off for one or more lamps (center or outer)
  • Dash may show brake/ABS warning or related message
  • Cruise control or shift interlock may be disabled on some models
  • DTC stored and possible reduced functionality of driver assistance systems that read brake input

What to check

  • Use scan tool to confirm B1484 stored and note freeze frame data
  • Visually inspect rear stop lamps (bulbs/LED lenses) and connectors for damage or corrosion
  • Check fuses and fusible links related to brake/stop lamp circuit
  • Operate brake pedal and confirm which lamps illuminate (left/right/center)
  • Back-probe brake light switch connector and lamp socket(s) to measure voltage with pedal pressed/released
  • Perform continuity/ohm check between brake switch output terminal and each stop lamp positive terminal with battery disconnected

Signal parameters

  • Supply voltage at brake light switch (with ignition on): ~11–14 V (battery voltage)
  • At lamp positive terminal when pedal released: ~0 V; when pedal pressed: ~11–14 V (depending on circuit design)
  • Continuity (ohms) from brake switch output to lamp positive: low ohms; open circuit indicated by OL/infinite
  • Typical stop lamp filament resistance (incandescent): a few ohms to tens of ohms; LEDs will show different characteristics—check as assemblies; current draw when lamp ON: incandescent lamps = several hundred mA per filament; LEDs much lower

Diagnostic algorithm

  1. Read and record freeze frame and any related DTCs with a scan tool; do not clear codes yet
  2. Visually inspect rear lamp assemblies, connectors and ground points for corrosion, damage or disconnection; replace/clean as needed
  3. Check relevant fuses and replace if blown; if fuse blows repeatedly, suspect short to ground downstream
  4. Confirm operation: have an assistant press the brake pedal while you observe each stop lamp; note which lamps fail to illuminate
  5. Back-probe brake light switch connector: measure voltage on switch input and output with ignition on. Expected: battery voltage to switch input; output should be 0 V (or ground depending on design) with pedal released and battery voltage with pedal pressed
  6. If no voltage at switch output when pressed, remove switch and bench-test for continuity/resistance or replace if faulty
  7. If switch output is correct, measure voltage at lamp socket(s) while pedal is pressed. If no voltage at socket, perform continuity test between switch output terminal and lamp positive terminal with battery disconnected
  8. Inspect and test ground at lamp negative terminal; a bad ground can mimic open-circuit symptoms
  9. If continuity/open-circuit is found in wiring, trace wiring harness to locate damage; repair with proper splices, heat-shrink, and corrosion protection
  10. If wiring and switch test good but fault remains, inspect connectors at BCM/body module and check for BCM input pin continuity and voltage. Consider BCM replacement only after eliminating wiring and component failures
  11. After repairs, clear codes, cycle ignition and perform functional test with brake pedal; confirm no return of B1484 and proper lamp operation

Likely causes

  • Wiring damage (chaffed, pinched or broken conductor) between switch and rear lamps
  • Failed brake light switch or misadjusted switch plunger
  • Blown fuse or failed bulb filament/LED module causing open circuit
  • Corroded connector at rear lamp or at brake switch causing intermittent/open contact

Fault status

⚠️ Status
Open circuit detected between brake switch and stop lamp circuit — brake pedal input signal not reaching stop lamps.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1480 B1482 B1485 U0121 U0123
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

B1484

Other B — Body

Brake Pedal Input Open Circuit

Brand: Other
Type: B — Body
Views: UK: 23 EN: 106 RU: 31
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or broken wiring between brake switch and stop lamps
  • Faulty brake light (stop lamp) switch
  • Blown fuse or fusible link for brake/stop lamps
  • Burnt-out or disconnected stop lamp bulb(s) or LED module failure
  • Corroded/damaged connectors (at switch, lamps or body control module)
  • Poor ground at lamp(s) or body control module

Symptoms

  • Brake lights do not illuminate when brake pedal is pressed or are intermittent
  • Brake lights stay off for one or more lamps (center or outer)
  • Dash may show brake/ABS warning or related message
  • Cruise control or shift interlock may be disabled on some models
  • DTC stored and possible reduced functionality of driver assistance systems that read brake input

What to check

  • Use scan tool to confirm B1484 stored and note freeze frame data
  • Visually inspect rear stop lamps (bulbs/LED lenses) and connectors for damage or corrosion
  • Check fuses and fusible links related to brake/stop lamp circuit
  • Operate brake pedal and confirm which lamps illuminate (left/right/center)
  • Back-probe brake light switch connector and lamp socket(s) to measure voltage with pedal pressed/released
  • Perform continuity/ohm check between brake switch output terminal and each stop lamp positive terminal with battery disconnected

Signal parameters

  • Supply voltage at brake light switch (with ignition on): ~11–14 V (battery voltage)
  • At lamp positive terminal when pedal released: ~0 V; when pedal pressed: ~11–14 V (depending on circuit design)
  • Continuity (ohms) from brake switch output to lamp positive: low ohms; open circuit indicated by OL/infinite
  • Typical stop lamp filament resistance (incandescent): a few ohms to tens of ohms; LEDs will show different characteristics—check as assemblies; current draw when lamp ON: incandescent lamps = several hundred mA per filament; LEDs much lower

Diagnostic algorithm

  1. Read and record freeze frame and any related DTCs with a scan tool; do not clear codes yet
  2. Visually inspect rear lamp assemblies, connectors and ground points for corrosion, damage or disconnection; replace/clean as needed
  3. Check relevant fuses and replace if blown; if fuse blows repeatedly, suspect short to ground downstream
  4. Confirm operation: have an assistant press the brake pedal while you observe each stop lamp; note which lamps fail to illuminate
  5. Back-probe brake light switch connector: measure voltage on switch input and output with ignition on. Expected: battery voltage to switch input; output should be 0 V (or ground depending on design) with pedal released and battery voltage with pedal pressed
  6. If no voltage at switch output when pressed, remove switch and bench-test for continuity/resistance or replace if faulty
  7. If switch output is correct, measure voltage at lamp socket(s) while pedal is pressed. If no voltage at socket, perform continuity test between switch output terminal and lamp positive terminal with battery disconnected
  8. Inspect and test ground at lamp negative terminal; a bad ground can mimic open-circuit symptoms
  9. If continuity/open-circuit is found in wiring, trace wiring harness to locate damage; repair with proper splices, heat-shrink, and corrosion protection
  10. If wiring and switch test good but fault remains, inspect connectors at BCM/body module and check for BCM input pin continuity and voltage. Consider BCM replacement only after eliminating wiring and component failures
  11. After repairs, clear codes, cycle ignition and perform functional test with brake pedal; confirm no return of B1484 and proper lamp operation

Likely causes

  • Wiring damage (chaffed, pinched or broken conductor) between switch and rear lamps
  • Failed brake light switch or misadjusted switch plunger
  • Blown fuse or failed bulb filament/LED module causing open circuit
  • Corroded connector at rear lamp or at brake switch causing intermittent/open contact

Fault status

⚠️ Status
Open circuit detected between brake switch and stop lamp circuit — brake pedal input signal not reaching stop lamps.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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B1480 B1482 B1485 U0121 U0123
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